Keto Supplements That Work—and the Ones That Are Useless

This is the ultimate guide on the best supplements for keto. No affiliate links—only pure knowledge. It’s long (and keeps getting longer). If you want to save time and get the best keto supplements without diving into too much theory, check out our Keto Supplements Buyers Guide.

Meet the U.S., where nearly 50% of adults consume more than 50,000 various dietary supplement products on a daily basis, creating a market value of almost $40 billion a year.

What does this mean?

America’s got the most expensive pee, that’s what. The majority of supplements are a waste of money, and keto supplements aren’t an exception (as we will explain later in this article).

But first, let’s look at the ones that work.

Keto Supplements That You Need

A ketogenic diet makes demands of anyone who wants to follow it. If you don’t live up, you get the keto flu and the other infamous by-effects of transitioning to a low-carb lifestyle.

What demands? For example, to feed yourself with proper nutrition.

And not only macronutrients such as fat, protein, and carbs. You need to watch your micronutrients, which are vitamins and minerals.

Even water and oxygen are nutrients. Everything that gets into your body and can be used is a nutrient.

If you don’t get enough nutrients from your diet, you should supplement them. But if you’re already thinking about exogenous ketones and MCT oils, I have to disappoint you.

This is what people really lack on keto.


Meet magnesium, the ninth most abundant element in the Milky Way Galaxy.

Unsurprisingly, it’s essential (NIH fact sheet for health professionals) for many important processes in the human body, such as:

  • Blood glucose control
  • Blood pressure regulation
  • Nerve and muscle function
  • Energy production
  • Bone development
  • DNA synthesis

And many others. Actually, I won’t lie if I say that magnesium, either directly or indirectly, affects nearly every system in your body. Every cell in your body needs magnesium.

Why is magnesium important on keto?

To make it clear—magnesium is important on every diet, whether it’s known as vegan, paleo, keto, carnivore, or as any other eating routine with a fancy name.

Keto, however, presents the greatest risk because it makes you drain a lot of water during the transition state, washing magnesium out of the body.

Also, the more you drink, the more you pee, and the more you pee, the more minerals are excreted in your urine.

Usually, kidneys excrete about 120 mg magnesium into the urine every day. Double the amount of urine, and you pretty much double the magnesium excretion.

Of course, it might not be that linear, but you get the direction.

(And we usually drink a lot on keto.)

One more important point we can’t forget to ask is what was your diet before switching to keto?

Did you eat only super-healthy organic foods and lots of greens? Or did you have refined carbs, burgers, pasta, and tons of cheese dipping sauce?

If you came from the second camp, which is called the standard American diet, there’s nearly a 50% chance you didn’t consume enough magnesium. [Suboptimal magnesium status in the United States: are the health consequences underestimated?]

Combine this with rapid magnesium excretion after turning to keto, and you’ll get the idea of why it is important to supplement it.

How can you assess magnesium deficiency?

Because magnesium is mainly located inside cells—in bones, muscles, and other tissues—measuring its deficiency is a tricky task.

Your blood only contains less than one percent of your total magnesium, and your body is hardwired to maintain this specific concentration. It is vital for life—if the concentration is not right, you might die.

Healthcare facilities offer something called a serum magnesium test, but it’s not representative at all. You might suffer from severe magnesium depletion, but your serum magnesium will be absolutely normal.

There’s another test called a RBC magnesium test, which evaluates the level of magnesium in red blood cells. It’s more expensive, but at the same time, it doesn’t bring anything new to the table except for one more fancy way for myriads of clinics to get your money.

Simply speaking, even if your tissues are deficient in magnesium, your blood magnesium will be fine in 99.9% of cases.

(And if blood tests show low magnesium, you’re in serious trouble and you probably know that without me telling you.)

The best, and also free, way to check for magnesium deficiency is to see whether you have any of the most common symptoms.

What are the symptoms of having low or deficient magnesium?

Having any of these symptoms might be a sign of low magnesium:

  • Fatigue
  • Depressed mood
  • Muscle cramps
  • Chronicle constipation
  • Insomnia
  • High blood pressure

These symptoms don’t always mean you are deficient in magnesium (because our body is a highly sophisticated system), but they are very common.

As for me, every time I jump up in the middle of the night grabbing my leg and leaping around the room, I know it’s time to start supplementing magnesium.

However, supplementing magnesium is the second step. The first one is to make sure you get enough magnesium from food.

What are the best keto sources of magnesium?

Many keto-friendly foods contain magnesium: fish, meat, nuts, seeds, veggies, and leafy greens.

But you want exact numbers, don’t you?

Here they are:


Make sure to add these foods to your diet.

As for sweets, dark chocolate (70–85%) contains four times more magnesium than milk chocolate. Precisely, ~228 mg of magnesium per 100g.

Now let’s have a look at various magnesium supplements.

The best magnesium supplements

In a perfect world, there’s only one magnesium supplement, which is effective and cheap.

In our world, if you come to the pharmacy, you’ll see that magnesium comes in many various forms: oxide, gluconate, hydroxide, sulfate, aspartate, carbonate, malate, glycinate, chloride, taurate, orotate, citrate, L-Threonate.

The main difference between all of them is how efficiently your body can absorb them and to what degree they act as a laxative.

Try to avoid magnesium in these forms: oxide and hydroxide (laxative and poorly absorbed), aspartate and gluconate (might increase neuronal excitability), sulfate (good in a bath but not orally), and carbonate (laxative).

They are not bad, but they are inferior to the other types that are absorbed much better.

Opt for magnesium malate, glycinate, chloride, taurate, orotate, citrate, and L-Threonate.

As for the daily dosage amounts, forget about “if a little is good, a lot is better” thinking. Stick to the instructions.

Also, according to the Dietary Reference Intakes (DRIs) by the National Academy of Medicine, the estimated average daily requirements for magnesium are 350 mg for adults.


Following keto might put you at risk of magnesium deficiency. Also, the more you drink and sweat, the more magnesium is washed out of your body.

Muscle cramps, mental disorders, fatigue, high blood pressure—these are some of the symptoms. If you notice them, getting a good magnesium supplement might help.

Vitamin D

Vitamin D is the foundation of being healthy—it’s not just another vitamin your doctor can prescribe you.

In fact, it’s not even really a vitamin.

What we call vitamin D is actually a group of fat-soluble secosteroids that often make researchers babble about whether to classify them as hormones, prohormones, prehormones, or, as we already know them, vitamins.

This group includes at least 5 different elements: D1, D2, D3, D4, and D5 (some also include D6). We’re still far from fully understanding each and every role vitamin D plays in the human body, but we already know a lot.

What we know about vitamin D

When vitamin D was initially discovered, scientists didn’t realize that, unlike other vitamins, humans can synthesize it through sunlight exposure (and hence it’s not technically a vitamin). By definition, a vitamin is an essential micronutrient that can’t be synthesized in the human body and thus must be obtained through diet.

Because it was the fourth “vitamin” to be named, scientists called it vitamin “D.”

Contemporary science considers two vitamin D compounds—vitamins D2 and D3—to be the most important for humans.

So, to make it clear—when we speak about vitamin D in general, we usually mean either D2, or D3, or both at the same time.

Vitamin D2 (ergocalciferol) can’t be synthesized in humans and is only found in food. You will need a prescription to buy a vitamin D2 supplement.

Vitamin D3 (cholecalciferol) is made by your skin when it’s exposed to sunlight and is also found in food. You don’t need a prescription to get a vitamin D3 supplement.

Both of them are considered to have similar effects on your health. However, studies show that vitamin D3 might be preferable because we absorb and activate it better.

In order to use the vitamin D in supplements, your body needs to activate it first. This activation takes two steps—the first one takes place in the liver and the second one occurs in the kidney. During these steps, vitamins D2 and D3 are converted into their active forms: D2 first transforms into ercalcidiol (in the liver) and then into ercalcitriol (in the kidney). Likewise, D3 turns into calcifediol and then into calcitriol.

Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis.

Why is vitamin D important on keto?

We’ve all heard that vitamin D is important, but the question is:

What makes vitamin D, specifically, important on keto?

I could start breeding demagoguery on how elimination diets make tracking your nutrients more important than ever (kinda like I did in the section about magnesium where it is relevant indeed), but it would simply be not true for vitamin D.

The thing is, supplementing vitamin D on keto isn’t special.

But ask yourself a question:

Why did you start following keto? Wasn’t it to live a longer, healthier, and happier life?

It makes very little sense to just exclude carbs and hope for the best. This is the first, yet very small, step. If you don’t want to waste your time, you should pay attention to the other nutrients.

How can you assess vitamin D deficiency?

Unlike magnesium, vitamin D deficiency is easily measured via a 25(OH)D test (also called a 25-hydroxy vitamin D test).

Everything below 12 ng/ml indicates a severe deficiency, everything roughly above 30 ng/ml and below 100 ng/ml is considered normal.

Many doctors, especially those who specialize in vitamin D, recommend keeping your vitamin D level somewhere between 50 and 90 ng/ml to get all the benefits.

I would totally recommend that everybody who takes care of their health and has free money take the vitamin D test at least once a year.

But for those of us who live in the U.S., there’s a quick free test:

Take a globe and draw a line between L.A. and Atlanta.

You live above the line. Do you take vitamin D supplements? No?

You are deficient in vitamin D.

You live below the line. Do you spend at least half an hour a day naked in the sun? No? Do you take supplements? No?

You are deficient in vitamin D.

This one isn’t as accurate as a lab test, but it can pretty much tell you whether you’re deficient in vitamin D, especially if you notice any of the symptoms mentioned below.

What are the symptoms of having low vitamin D?

Here are the most common signs of being deficient in vitamin D:

  • Bone pain and fragility. Vitamin D deficiency softens bones, leading to their deformation, bending, bowing, and frangibility. Rickets in children and osteoporosis in adults are because of low vitamin D.
  • Chronic fatigue. A myriad of things might result in chronic fatigue, and vitamin D deficiency is one of them.
  • Frequent viral infections. If you catch a cold way too often, low vitamin D might be one of the issues behind it.
  • Depressed mood. A vitamin D deficiency test is part of the blood work for treating clinical depression. But even if you’re not depressed in the medical sense but just apathetic all the time, it might be a sign that you need to start supplementing vitamin D.
  • Slow wound healing. Vitamin D is responsible for hundreds of chemical reactions in your skin, including healing.
  • Pangs of muscle pain and muscle weakness. If your muscles sometimes hurt for no reason, and you feel that even raising your arms is too hard for you, it might be connected with vitamin D deficiency.

To at least partly avoid these symptoms, make sure you get enough vitamin D from all possible sources.

What are the best keto sources of vitamin D?

The best source of vitamin D is the sun—it’s free, it’s effective, and it has no carbs.

Of course sunlight has no carbs! But did you know that sunlight is actually the reason carbs even exist? If you want to know how on earth this can be true, check out our big-ass guide on carbs.

The second best source is animal-based food. Vitamin D is fat-soluble, and therefore it’s present in fatty foods derived from animals that were exposed to sunlight.

These foods include egg yolks, grass-fed butter, beef liver, pasture-raised pork, and fatty fish.

The only plant-based source (except for fortified foods) of vitamin D is mushrooms. But unlike animals, they synthesize vitamin D2 when exposed to sunlight.

Opt for UV-treated mushrooms because if manufacturers grow them in the dark, they will contain almost no D2. Wild mushrooms are also rich in D2, but I avoid eating wild mushrooms and can’t tell you anything about them.

Likewise to mushrooms, fortified foods contain vitamin D2 and hence are not the best source. Still they’re better than nothing though.

But even if your diet is perfect, unless you’re exposed to the sun all year long, you probably lack vitamin D.

That’s why oftentimes you should supplement it.

How to supplement vitamin D

As I already mentioned, only vitamins D2 and D3 from the entire vitamin D group are thought to be important for humans, and they are both considered interchangeable.

Vitamin D2 is prescribable only, so you need to visit your doctor and do as he says.

Vitamin D3 is over-the-counter and is considered to be more efficient. Doctors who don’t follow the changes in contemporary medicine often think that if something is prescribable, it’s better. That’s why they usually prescribe vitamin D2 instead of D3.

This is good news for all of us who just want to supplement vitamin D without visiting a doctor.

In the U.S., the recommended daily amount of vitamin D for adults is 600 IU, and the tolerable upper intake level is 4000 IU. (Issued by the National Academy of Medicine.)

Some specialists recommend their patients take up to 10000 IU a day because they believe that the above-mentioned numbers are understated.

The reason they do it is that vitamin D is not always fully absorbed.

An average human can only absorb about 1200 IU a day through his gut, but to achieve that, he might take from 2000 to 10000 IU a day, they say.

Some of them also say that there’s no such thing as taking too much vitamin D and that there are no serious studies that prove vitamin D can be toxic.

However, I do not advocate any certain numbers. It’s up to you to decide how much vitamin D to take per day. I personally take 2500 IU and feel great.


Let’s face it—you’re most likely deficient in vitamin D.

The foundation of being healthy, vitamin D, is often what makes the difference between the happy and active, and sad and always-tired versions of you.

Omega 3 (EPA and DHA)

Omega 3 is one of the two essential fatty acids that humans can’t synthesize and therefore, have to ingest through diet. The second one is, surprise, omega 6.

Essential fatty acids are essential for real—they are not like “essential oils” where “essential” indicates that they contain the essence of plants. These fatty acids are required for a number of vital processes inside the human body.

If you lack omega 3, you have to supply it. Just like vitamins. By the way, when omega 3 and omega 6 were first discovered in 1923, they were called “vitamin F” but were reclassified as fats and renamed 6 years later.

But before rushing to the local pharmacy, let’s dive into some theory.

How does omega 3 help improve health?

Everyone knows that omega 3 is good for human health.

Just google its benefits and you’ll get an infinite list, from lowering cancer risks to protecting from cardiac death to reducing inflammation to improving mental health.

How can omega 3 be this beneficial?

It’s surprisingly easy to understand it when you dive just a little bit into how your body works. I know you haven’t asked for this but here it comes—boring theory.

If, as luck would have it, you’re an ordinary human from the planet Earth, you’re made of cells. Precisely, dozens of trillions of cells.

Each cell is a “complete combat unit”—it has a body, it has inner organs called organelles, it has its purpose, and it communicates with the outside world.

Being healthy on a very basic level means that your cells are healthy: their bodies and organelles are fine, the cells follow their mission, and they effectively communicate with each other.

The more “broken” cells you have, the more unhealthy you are. Cells break in many ways: some of them die, some stop following their mission, some get their bodies and organs damaged, and others impair their ability to communicate with other cells.

Just like human bodies are covered by skin, cells are covered by a thing called a cell membrane, which separates the interior of the cell from the environment.

cell structure

Cell organelles are also covered by membranes; moreover, when a cell communicates with the outside world, it sends various things from inside to outside (and vice versa) in special spherical vesicles that are covered by membranes too.

Likewise to various skin conditions, which can affect how efficiently we communicate with others (and eventually lead to very different life outcomes), the quality of cell membranes affects how efficiently cells communicate with each other, and how efficiently cell organelles do what they do.

Which, in turn, can lead to very different health outcomes.

And the most important question is:

How on earth is this connected with omega 3 fatty acids?

Cell membranes are scientifically called phospholipid bilayer membranes, indicating that they are mainly made of phospholipids, which are types of fat.

For the sake of simplification, let’s call phospholipids “good” fats because they improve something called membrane fluidity.

Membrane fluidity affects the rotation and diffusion of various biomolecules within the membrane—the higher it is, the better everything is functioning.

Omega 3 fatty acids provide this so-called good fat that improves cell membranes.

Improving membranes is a passive role of omega 3.

The active role of omega 3 is that it’s used to form signaling molecules, eicosanoids, which help a cell communicate with nearby cells.

Cell-to-cell communication, or cell signaling, coordinates multiple-cell actions. It’s the foundation of development, tissue repair, and immunity.

Errors in cell signaling may cause various diseases.

If, as luck would have it, you’re an ordinary human from the planet Earth, you’re made of cells. Precisely, dozens of trillions of cells.

Each cell is a “complete combat unit”—it has a body, it has inner organs called organelles, it has its purpose, and it communicates with the outside world.

Being healthy on a very basic level means that your cells are healthy: their bodies and organelles are fine, the cells follow their mission, and they effectively communicate with each other.

The more “broken” cells you have, the more unhealthy you are. Cells break in many ways: some of them die, some stop following their mission, some get their bodies and organs damaged, and others impair their ability to communicate with other cells.

Just like human bodies are covered by skin, cells are covered by a thing called a cell membrane, which separates the interior of the cell from the environment.

Omega 3 is not a miraculous cure-all.

It doesn’t directly combat diseases or symptoms, but it simply makes our cells function better.

Which in the end can prevent us from becoming unhealthy.

However, not all omega 3 fatty acids are created equal.

What types of omega 3 fatty acids exist?

Science already knows more than ten different omega 3 fatty acids. However, only three of them are deemed to be involved in human physiology: ALA, EPA, and DHA.

ALA, or alpha-linolenic acid, is the most common omega 3 fatty acid in the Western diet.

The “linolenic” part of its name is derived from Greek “linon,” which means flax. Unsurprisingly, seed oils—especially chia and flaxseed oils—are the main keto sources of ALA.

Scientists consider ALA inferior to EPA and DHA for one reason—it’s not biologically active. In order to give you health benefits, ALA must be converted to EPA and DHA. When a compound is called biologically active, it means it has a clear effect on living beings in small quantities.

ALA is the parent omega 3 fatty acid—EPA and DHA can be synthesized from it by the human body. The process, however, is highly inefficient: conversion rates for EPA and DHA are about 6% and 3.8%, respectively.

Moreover, if your diet is rich in omega 6 (and the standard American diet is), these conversion rates are reduced by roughly 50%.

Diseases such as diabetes and certain allergies might reduce these conversion rates. Also, the older you are, the lower the conversion rates are.

Up to 99% of ingested ALA goes straight to energy, providing no additional benefits.

EPA, or eicosapentaenoic acid, is used to produce eicosanoids, which help your cells communicate.

Not all eicosanoids in the human body are derived from EPA, but those that are, are considered less inflammatory or even anti-inflammatory.

The main dietary sources of EPA are oily fish and edible algae.

Why is fish rich in omega 3?

Some researchers believe this is the result of their adaptation to cold.

Unsaturated fatty acids (e.g. omega 3) harden at lower temperatures than saturated fatty acids. (Olive oil isn’t hard even in the fridge whereas butter is.)

Therefore, omega 3 fatty acids make cell membranes of fish more fluid at cold temperatures.

On the other hand, it might be just the result of what fish eat.

However, fish do not synthesize omega-3s, but they consume smaller fishes that consume phytoplankton, which consumes microalgae, which originally produce omega 3 fatty acids.

Even though EPA is already biologically active, a portion of it can get converted to DHA.

DHA, or docosahexaenoic acid, is considered the most important omega 3 fatty acid in humans.

It’s a key structural component of the human brain, cerebral cortex, skin, and retina. Fifty percent (by weight) of brain cell membranes are composed of DHA. Sufficient DHA levels are associated with preventing premature cognitive decline.

Likewise to EPA, the main dietary sources of DHA are fatty fish and algae. The absolute majority of oily fish contain both EPA and DHA.

Why is omega 3 important on keto?

After everything I’ve written about omega-3s, it’s clear as day that getting them is important on any diet.

As for keto… frankly speaking, if you don’t entirely subsist on bacon and introduce seafood to your diet at least twice a week, supplementing omega 3 is not a burning question for you.

And yet relevant.

Because sometimes you need to take just a little bit more omega 3 than that herring has managed to accumulate in its tiny body.

How much omega 3 should you take?

The National Academy of Medicine (former IOM) hasn’t yet issued either recommended dietary allowances or tolerable upper limits for omega 3 intakes.

NAM has only issued adequate intakes: 1.6 g per day for males and 1.1 g for females as ALA. (Because ALA is the only essential omega 3, the rest can be produced from ALA.)

It’s not much.

However, many PhDs in medicine say that you need more than 1–2 g of ALA per day, and they themselves take significantly more omega-3s than NAM suggests.

Rhonda Patrick, for example, says that she takes 6 grams of omega 3 per day in EPA and DHA forms.

For me, 1 gram of omega 3 per day as EPA and DHA seems reasonable enough. But I’m actually curious to give 6 grams per day a try.

How can you assess omega 3 deficiency?

To figure out whether you’re deficient, you first need to assess your omega 3 levels.

An omega-3 index test can help you with that. It’s a measure of how many EPAs and DHAs are in your red blood cell membranes in comparison to other fatty acids.

This test will give you a number, roughly from 0 to 15, which will indicate that 0–15% of your red blood cell membranes are made of EPA and DHA.

How should you interpret these numbers?

Dr. William S Harris, the co-inventor of the omega-3 index test, proposed that your blood omega 3 level is a biomarker that indicates risk factors for coronary heart disease mortality. He identified three zones:

  • High risk, below 4%.
  • Intermediate risk, 4–8%.
  • Low risk, above 8%.

Certain studies suggest that there might indeed be a correlation between omega 3 blood level and the risk of coronary heart disease.

In this study from Japan, 18,645 patients were randomly assigned to receive either 1.8g of EPA with statins or statins only each day.

After a mean follow-up of 4.6 years, in patients who had a previous history of coronary heart disease and who were given EPA, major coronary events were reduced by 19% in relation to the statin-only group.

However, I don’t see a strong reason to take this test unless you’re just curious or if your doctor tells you to do so.

What are the symptoms of having low omega 3?

Rough, scaly skin, as well as dermatitis, might indicate that you’re deficient in omega 3.

However, these diseases have multiple origins, including unknown ones, and low omega 3 levels are just one of them. Moreover, scientists still don’t know the exact point in omega 3 concentration below or above which these symptoms occur.

Is having too much omega 3 safe?

Nothing is safe when you have too much of it. “Too much” is harmful by definition.

The question is, how much is too much?

We know that the National Academy of Medicine in the U.S. doesn’t specify any tolerable upper intake levels for omega 3.

But NAM also says that 2–15 g of EPA/DHA/both daily might reduce immune function by suppressing inflammation, and also increase bleeding time.

Which makes sense because inflammation is not bad in itself—it’s part of the process of fighting harmful viruses and bacteria.

Too much inflammation might be bad, but so is too little inflammation. Too little omega 3 is bad, but so is too much omega 3.

According to the European Food Safety Authority, it appears to be safe to consume up to 5 g omega 3 per day in the long-term.

It might be reasonable to not exceed these numbers, even though certain scientists do it.

The best keto food sources of omega 3 fatty acids

I already mentioned that fatty fish is the best source of EPA and DHA omega 3, and flax seeds and chia seeds are the best sources of ALA omega 3.

This diagram shows the difference in omega 3 content in various foods.

*All values are taken from the USDA National Nutrient Database.

The difference is significant indeed, but this diagram might also create a false impression that fish contain very little omega 3.

This is not true.

The issue is that in this diagram we compare values for a hundred grams, and we rarely consume a hundred grams of any oil per day. However, we usually get more than a hundred grams of raw fish in a single serving.

Let’s pick out the foods with the top omega 3 content and transform this data into a more applicable form.

How we can transform it:

  • We take exactly the same data and convert ALA to EPA based on 5% conversion rates.
  • Human bodies then convert some EPA to DHA, but “some” is a vague number and thus we will not calculate it. EPA is already biologically active.
  • We adjust portion sizes to match what we usually get in real life.

Here is the new diagram:

Types of fatty acids in various foods (ALA converted to EPA with 5% rate)

Two tablespoons of vegetable oil seems like something we can get within one day. So does seven ounces of cooked fish—one good piece.

Two tbsp of flaxseed oil will give you roughly 0.7g EPA at the 5% conversion rate. Seven oz of herring will give you 1.75g EPA and 1.75g DHA, which is 5 times more than in 2 tbsp of flax oil.

Not to mention that the 5% conversion rate is only achievable if you’re a woman—men’s ALA to EPA conversion rates are many times smaller due to physiological reasons.

With due respect to vegetable oils, if you want to get enough omega 3 from food, you have to eat a lot of fish.

If you don’t, you better supplement omega 3.

How to choose omega 3 supplements

Imagine that we went nuts and decided to pick out the worst supplement.

What would it be?

Here’s our set of criteria: the worst supplement is not safe, has poor quality, hasn’t been tested, is polluted by various toxins, and barely works.

But costs a fortune.

Sounds unrealistic? Far from it, but I promised to give no product links in this guide.

When choosing the best omega 3 supplement, you should NOT do this:

  • Listen to celebrities promoting products for money.
  • Take bold claims on trust and believe marketing tricks.
  • Mistake best-selling for best.

What should you do?

Find a product that is safe, high-quality, tested, purified, that works, and is reasonably priced for what it provides.


By monitoring the results of independent lab supplement testing.

My favorite service is—they buy supplements off retail shelves and test them in their chemistry labs.

(I do not get any money for promoting Labdoor, I just share what I like.)

All the products are tested using exactly the same set of criteria and get their score according to the same scale:

*an example of their scale

For omega 3, along with EPA/DHA content, they measure levels of toxins:

*an example of how they list the amount of toxins for a random omega 3 supplement

You can read more about Labdoor, their testing, and scoring processes here.

The only issue is that Labdoor compares the efficacy of supplements without comparing their prices. If one supplement is twice as efficient as another but costs six times more, it gets higher rankings, but you’re paying three times more money for the exact same result.

Nevertheless, this issue can by no means diminish what they do.

If you want to get a really good omega 3 supplement, go to Labdoor and get something from the top of their rankings.

Fish oil vs krill oil

The last but not the least thing to discuss is the difference between fish and krill oils.

Fish oil contains omega 3 fatty acids in the form of triglycerides. Triglycerides are so-called storage lipids—vertebrates (including humans) use them to store fatty acids.

When your body wants to use stored fat, it first has to break triglycerides down into fatty acids and only then use these fatty acids for its needs.

Krill oil contains omega 3 fatty acids in the form of phospholipids. These are so-called structural lipids—animals use them to build certain structures, for example, cell membranes.

Your body can use phospholipids as is, and it can also break them down into fatty acids for further use.

The main difference is how difficult it is for your body to digest both of these forms.

To break down triglycerides, your body has to use bile to emulsify them. Without bile, you can’t digest triglycerides and get omega 3 fatty acids.

If you lack a gallbladder, or if you have problems with bile production, a huge amount of triglycerides can pass your digestive tract undigested.

If you have fish burps and/or diarrhea after taking fish oil supplements, it might be a sign that you don’t have enough bile to break down the triglycerides in fish oil.

In contrast, your body doesn’t need bile to absorb phospholipids. It only needs certain pancreatic enzymes that break phospholipids down for further use.

This might make krill oil more bioavailable than fish oil, meaning that you need to supply less of it to maintain the same blood omega 3 levels.

(As for me, this benefit is questionable. If you don’t have problems with fat digestion, krill oil is not beneficial just because it comes in the other form. Your body can break down triglycerides into building blocks and create phospholipids out of them. And if you do have problems with fat digestion, you shouldn’t follow keto in the first place.)

The second benefit of krill oil is that it’s less toxic.

Krill are small shrimp-like crustaceans that reside on the bottom of the food chain. Their lifespan is short and they simply can’t accumulate high levels of toxins before getting caught.

Fish oil is made of fish, which are more toxic than tiny little krill.

Even though I listed the two benefits that have clear reasoning behind them, the current weight of scientific evidence does not allow me to say that krill oil is better than fish oil.

Fish oil can be purified from toxins, and certain studies question the higher bioavailability of krill oil.

One more thing about fish oil.

There are several forms of fish oil on the market: natural triglycerides (TG), ethyl esters (EE), and concentrated re-esterified triglycerides (rTG).

In nature, fish oil comes only in the triglyceride form, but when manufacturers want to condense more omega-3s into a single serving, they transesterify fish oil into the ethyl ester (EE) form.

This is a so-called synthetic form of fish oil.

To bring it back to a triglyceride form, manufactures re-esterify it and get the rTG form.

We don’t have enough scientific evidence to either claim EE and rTG fish oils absolutely safe, or harmful.

But we all remember the history of trans fats.

When big money is involved, it might take us half a century to realize that something we consider healthy is actually ruining our health.

I’m not saying EE and rTG fish oils can ruin your health, but I’m not saying that they can’t.

Nobody knows yet.

That’s why if you asked for my advice, I would advocate taking TG fish oil and krill oil and avoiding EE and rTG fish oils.


Omega 3 fatty acids improve cell membrane fluidity and help your cells communicate with each other more efficiently.

It is no exaggeration to say that being deficient in omega 3 will affect each and every cell in your body. Ultimately, it will affect how you look, feel, and live.

Even though a lack of omega 3 is not as dangerous as, say, a lack of magnesium, supplementing omega 3 is relevant for nearly everyone.

Magnesium, vitamin D, and omega 3 fatty acids are the three nutrients that everyone should look after.

I could say that they are especially important on keto because of dietary restrictions, but they are always important. However, magnesium is most at risk because many magnesium-rich foods contain carbs.

The best news is that these supplements won’t blow a hole in your budget. Usually, they are quite cheap.

Guess what can tear your budget apart?

Worthless supplements.

Keto Supplements That Are Worthless

Alright, the word “worthless” is a clickbait, but you wouldn’t have opened it otherwise, would you?

As Socrates said, “Nothing is absolutely worthless. If you look closely, you can find merit in a piece of dog sh…” Well, I’ve actually made this one up, he never said that.

But he could have. He was a prolific teacher, a thinker, and a philosopher. He was a wise man. Only a wise man would have found that everything in the world is relative.

That man was Albert… Ok, forget about it.

I just want to say that everything can be beneficial, even pure water. Moreover, the placebo effect is real, especially when you spend your hard-earned money on something.

But you expect to get something more than a placebo for your buck, don’t you?

According to the Google dictionary, a supplement is “a thing added to something else in order to complete or enhance it, or a substance taken to remedy the deficiencies in a person’s diet”.

Worthless supplements do neither of those.

Let’s examine some of them.

Exogenous Ketones

Supplementing exogenous ketones is the most ineffective way to spend your money. However, if you do intend to throw them away, quite efficient.

Unless you’re a competing endurance athlete, of course.

Let’s break it down.

The anatomy of ketosis

Ketosis is a state of an increased level of ketones in the blood. Increased is underlined because some amount of ketones is always present in the bloodstream.

When you deplete your body’s glucose, your liver increases fatty acid metabolism and starts to produce more ketones for fuel. This is a normal response to low glucose and is called physiologic ketosis.

Three things usually cause physiologic ketosis: fasting or starving, carb restriction, and prolonged physical exercise.

Physiologic ketosis is inextricably connected with your liver producing ketones from fatty acids. As you enter the physiologic ketosis state, it won’t be interrupted until you eat a certain amount of carbohydrates at once.

Nevertheless, there’s a thing I call fake ketosis. Technically, fake ketosis is also a state of an increased level of ketones in the blood, but it will end after a period of time.

What causes fake ketosis?

Aside from producing ketones inside your body, which is called endogenous ketone production, the only way to get them is from the outside, or exogenously.

Exogenous ketones are not harmful—structurally, they are identical to endogenous ketones—the only difference is that they aren’t produced by your liver.

If you ingest exogenous ketones before lowering your glucose reserves and then take a blood/urine test, it will show an elevated level of ketones. Technically, you’re in ketosis.

What makes it fake is that when you have utilized these ketones (partly for energy, partly via urine), you will come back to a state of glycolysis, or using sugar for fuel.

Moreover, while you’re in fake ketosis, glucose utilization in your body is reduced, consequently delaying your physiologic ketosis.

Is fake ketosis bad?

I wouldn’t say it’s bad—it’s pointless.

The absolute majority of us started keto because we wanted to lose fat. To lose fat, we need our body to break down adipose tissue into fatty acids and then use these fatty acids for multiple purposes, including their use as fuel.

To burn body fat for fuel, you need to spend more energy than you get from your diet—that’s the law no living being is able to break. When you ingest exogenous ketones, you basically consume additional energy.

If you didn’t take exogenous ketones, you could’ve burned some body fat to get this energy.

As for me, it’s literally pointless. Our goal is long-term physiologic ketosis, which won’t occur in the presence of high glucose. To speed up getting into ketosis, you should focus on depleting yourself of glucose and not on getting more ketones from the outside.

Is there a situation when exogenous ketones are good?

I can come up with three possible situations:

For the sake of experiment. If you want to experience how you’d feel during ketosis and don’t want to wait until you get into physiologic ketosis, you can try exogenous ketones.

To fight one of the many possible causes of keto flu. Sometimes you can get keto flu when you already lack sufficient glucose but your liver doesn’t produce enough ketones yet. Taking exogenous ketones can help mitigate this phase.

You never know if this is your case until you try. Aside from that, keto flu has many origins: lack of vitamins and minerals, not being used to keto, producing too many ketones, various health issues, and other factors.

If you’re an endurance athlete during a hard training session or competition. Ketones are a very effective source of fuel for endurance performance, but the rate of ketone production in your body is limited. Exogenous ketones are an instant high-octane fuel for high-class athletes.

If you cycle, run, hike, or do anything like this simply to lose weight, using exogenous ketones makes no sense.

Do exogenous ketones put you in a state of deeper ketosis?

What is the deeper state of ketosis? Mathematically speaking, the more ketones you have in your blood, the deeper you are in ketosis.

Therefore, the answer is yes, taking exogenous ketones increases blood ketone concentration for a period of time and puts you deeper into ketosis for this period of time.

The next question is—does it make any sense?

Your body doesn’t burn fat for fun, it burns fat for energy. Unless you spend more energy than you consume, you won’t burn any fat no matter how deep into ketosis you are.

Yes, ketone bodies don’t get converted back into fat. But exogenous ketones are a source of energy that replaces endogenous ketones and therefore postpone body fat burning.

Do you want to be in the deepest ketosis ever but lose no fat?

It doesn’t make any sense to deepen your ketosis by taking artificial ketones. What matters for weight loss is how efficiently your body utilizes stored body fat.

Do exogenous ketones boost fat loss?

There is no serious scientific evidence to prove that taking exogenous ketones can directly boost either weight or fat loss.

If you know of any trustworthy studies that prove the opposite, please link them in the comment section.

Should I take exogenous ketones?

Let’s recall the definition of a supplement:

A thing added to something else in order to complete or enhance it,” or “a substance taken to remedy the deficiencies in a person’s diet”.

Can you be in ketosis and be deficient in ketones at the same time? No, you can’t. It’s only possible in the short-term during the transition from glycolysis to ketosis when you aren’t, in fact, in ketosis yet.

Do ketones complete or enhance a keto diet? No, they don’t. Does a fish enhance a fish diet? Do veggies enhance a vegan diet?

Unless you know exactly what you need exogenous ketones for, they are just a waste of money.


Exogenous ketones have a very narrow practical application. They are no more than a source of instant energy.

Supplementing them most likely will not help you lose more fat.


Let’s say you’re an endurance athlete in ketosis. You’ve just read the previous section about exogenous ketones, ordered a bunch of those, and are now looking for how to spend the rest of your money.

“What else should I get?”—you’re asking yourself. Shut up and get some MCT oil supplements, they are worth it.

But only if you train hard. If you don’t… well, I’m sorry to disappoint you.

Let me explain.

What Is MCT oil?

Before we dive into science, let’s define the terminology around fats and oils to avoid confusion.

Lipid, from Greek lipo meaning fat, is something that is insoluble in water, soluble in organic solvents, and can be utilized by living cells. Lipid is the general term for everything that we know as fat.

Oil specifies a lipid that is liquid at room temperature.

Fat in its strict sense indicates a lipid that is solid at room temperature. However, in food science, fat is used as a synonym for lipid.

Lipids exist in a myriad of different forms. One of the most common lipid compounds is called a triglyceride. Triglycerides are the main building blocks of human, animal, and vegetable fat.

Chemically, a triglyceride consists of one glycerol molecule that is linked with three fatty acids. The structure of the glycerol molecule is always the same, but the three fatty acids might differ (hence various types of triglycerides).

Fatty acids are chains of carbon atoms linked with hydrogen and oxygen atoms. Basically, fatty acids are just raw material—your body can create various lipids using fatty acids, it can utilize fatty acids for energy, or it can break fatty acids down into ketones.

These chains of atoms vary in length from short to very long, depending on the number of carbon atoms in the chain.

The MCT part stands for medium-chain triglycerides. Hence MCT oil is the oil that is comprised of triglycerides that have medium-chain fatty acids in their structure.

What are medium-chain triglycerides?

Technically, medium-chain triglycerides are those that consist of fatty acids that have from 6 to 12 carbon atoms in their structure.

Precisely, these fatty acids:

  • C6 Caproic or hexanoic acid
  • C8 Caprylic or octanoic acid
  • C10 Capric or decanoic acid
  • C12 Lauric or dodecanoic acid

The numbers indicate how many carbon atoms are in the chain.

Medium-chain fatty acids are the GOATs. Alas, not because they are the greatest, but because of their unpleasant smell reminiscent of goats.

The genus of mammals that includes domestic goats and their wild relatives is called Capra. Hence, the common names: caproic, caprylic, and capric acids. Lauric acid is lucky enough to avoid having a goat odor.

It’s no wonder that goat milk is a good natural source of C6, C8, and C10 fatty acids—all together, they comprise 15% of the fat content in it.

Because of that smell, there must be a decent reason to use them as supplements, right?

Let’s find out.

The benefits of MCT oil

All the benefits of MCT oil stem from its structure.

The longer the carbon chain, the longer it takes to break it down for further use. Your body can break down C6 faster than C8, C8 faster than C10, and so on.

Medium-chain fatty acids are relatively short, and therefore, your body can use them quite quickly. The difference in speed is because MCTs bypass the liver, while the longer chains need the liver to break them down for further digestion.

Because MCTs bypass the liver, they don’t require bile salts for digestion.

Hence the first benefit of MCT oil—it’s easier to digest. This might be important for people with malnutrition, malabsorption, and fatty-acid metabolism disorders.

The second benefit of MCT oil derives from the first one. Because it’s easier to digest, your body can get energy faster. This might be important when you’re an athlete.

Every rule has an exception.

Only ~30% of lauric acid bypasses the liver, the rest doesn’t. That’s why some scientists argue that C12 should be treated as a long-chain fatty acid.

These two benefits of MCT oil are no doubt real. What else can be attributed to it?

Some studies back the use of MCTs as a weight loss supplement. Some claim that MCTs promote fat oxidation and reduce food intake. Some people also think that MCTs are linked to increased performance in physical activities.

Even though this might be true, two questions arise:

Can you trust these studies? A systematic review of the influence of the dietary intake of MCTs on body composition, energy expenditure, and satiety has shown that the results are inconclusive and that we need more controlled studies before we can claim anything.

Were these studies placebo-controlled? No, they were not.

Based on the weight of the current scientific evidence, let’s examine MCT oils using the criteria of a good supplement that we established in the section about exogenous ketones.

As Google says, a supplement is “a thing added to something else in order to complete or enhance it, or a substance taken to remedy the deficiencies in a person’s diet“.

Does MCT oil complete or enhance your diet? No. MCT oil doesn’t bring anything new to your table.

Does MCT oil remedy deficiencies in your diet? No. Medium-chain fatty acids are not essential and can be synthesized by your body. MCT oil can only help if you’re deficient in lipids in general, but so can regular food.

Should you take MCT oil supplements?

No, if you want to increase fat oxidation, burn more calories, reduce appetite, and promote weight loss. Even if these benefits do exist as some studies say, the effect is so insignificant that it isn’t worth paying money for.

Yes, if you need a burst of keto-friendly energy. Keep in mind that MCT oil doesn’t increase performance beyond what a source of fast energy is capable of.

How to pick the best MCT oil

Just pick anything that fits your budget and has at least 4 stars. The main difference between various MCT oils is how they are marketed.

A closing thought

When we speak about carbs and weight loss, we always say the longer it takes to digest, the better it is. That’s why whole carbs are “better” than refined carbs, and that’s why we avoid eating pure glucose.

Example: Fiber is made of glucose, but its structure is so complex that we can only partially digest it, and this fact is promoted as something good. Pure glucose is readily absorbed by your body, and that’s why it’s treated as something bad.

(Whereas with glucose, the devil lies in quantities but not qualities.)

At the same time, when we talk about fats, we somehow start nurturing the hypothesis that the faster it can be digested, the better it is.

This is absolutely not true. The longer it takes to digest, the better it is for long-term satiety. The shorter it takes to digest, the faster you get energy.

Supplementing MCT oil doesn’t provide any miraculous benefits. It gives you nothing in addition to what regular food can give you, aside from a possible placebo effect.

Of course, you can take it if you want. But as for keto on a budget, I totally wouldn’t recommend it.


MCT oil is easier to digest than the majority of other oils. It might be important for patients with malnutrition, malabsorption, and fatty-acid metabolism disorders.

Basically, MCT oil is a fast source of energy. It’s uncertain whether it can directly provide any special weight-loss benefits or improve performance in athletes.

Situational Keto Supplements

Some supplements are good, some are not. Some are indispensable, some are useless. Some are always worth paying for, some are worthless even if given away for free.

And some reside someplace in between these categories. Today they are great, and tomorrow they are totally useless.

They are situational. They remedy very specific deficiencies or enhance your performance in very particular cases.

But this guide is already too long, and I don’t want you to fall asleep. That’s why I’ll give you a very brief idea of what they are. For the rest, to the Google!


Creatine is useful when you are an athlete and aim to maximize muscle growth or/and to improve strength on keto.

(If you’re new to training, taking creatine supplements makes very little sense.)

Here’s how it works.

You’ve probably heard of ATP, which is also known as the energy currency of the cell. No matter whether you get energy from ketones or glucose—in order to use them, your cells first convert them to ATP.

Building muscle and strength is all about lifting heavy, and lifting heavy is all about muscle glycogen. When you perform heavy reps, your body converts muscle glycogen to ATP to give you energy.

When you follow a keto diet, you don’t have much glycogen in your muscles. You still have some, but very little. This happens because glycogen is made of glucose, and you don’t consume much glucose on keto.

Ketones and fatty acids can be used to fuel muscle contractions, but they are inferior for lifting heavy. Working out with heavy loads takes a lot of ATP, but your body can’t convert them to ATP fast enough.

You run out of fuel.

And here’s how creatine could help.

When you lift heavy, you don’t start with using glycogen right away. During the first several seconds of intense muscular effort, your body uses phosphocreatine to create ATP.

Not diving too much into science, phosphocreatine is a phosphorylated creatine molecule that can donate its phosphate group to ADP to create ATP via a rapid chemical reaction.

Simply speaking, phosphocreatine can give you energy way faster than ketones, fatty acids, and glucose.

The downside of the creatine system is that your body can’t store much phosphocreatine. Taking creatine supplements can help you increase your phosphocreatine reserves, and, as a result, increase the number of heavy reps you can perform.

Two things to remember:

Creatine is not an essential nutrient. Your body produces creatine from food, mainly from meat.

Supplementing creatine doesn’t make sense for beginners. Creatine won’t give you anything you couldn’t have achieved without it.

If you’re an athlete and you know how to train and why you train, supplementing creatine is definitely worth it.

If you’re not an athlete and just want to buy one more supplement because the internet tells you it will make you better/stronger/smarter, supplementing creatine is definitely not worth it.

Creatine monohydrate is the most well-researched form of creatine supplement, which has been used by athletes and studied by scientists for decades. If you want to start supplementing creatine, get creatine monohydrate.

Digestive Enzymes

Digestive enzymes help break food down into its building blocks.

Different enzymes target different substances. For example, amylases help break carbs down into simple sugars, proteases help break proteins down into amino acids, and lipases help break fats and oils down into fatty acids.

Your body is used to producing enzymes in particular quantities that help you digest your usual meals. When you change your diet, your body has to change this set of enzymes.

The transition phase can be hard. You increase the amount of fat in your diet, and your body has to respond with a proportional increase in lipase production. If it fails, you might get diarrhea, bloating, nausea, and other related problems.

Supplementing digestive enzymes can help you facilitate the transition stage.

And now my favorite part:

Say, you have been on keto a long time but… had just a little bit too much of something yummy for dinner or just opted for an unusual dish. No worries, you know what to do: take digestive enzymes.


Carnitine is the general name for several compounds, such as L-carnitine, acetyl-L-carnitine, propionyl-L-carnitine, and D-carnitine. However, carnitine in humans only exist in its L form; the D form is toxic.

Humans can synthesize carnitine from protein, and they can get carnitine from foods such as red meat and dairy; vegetable-based foods are low in carnitine.

Moreover, L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine can be converted back and forth into each other. Hence when I say carnitine, I mean all of its L forms in general, for the sake of simplicity.

The main function of carnitine is to aid in fatty acid transport into the mitochondria.

To see the importance of carnitine, you need to look at the path the majority of lipids take to become energy. Simply speaking, this is how it looks.

  1. Lipids are broken down into fatty acids, which then enter the blood. They are now called free fatty acids and float freely in the bloodstream.
  2. These free-floating fatty acids bind to carrier protein molecules, which carry them to the target cells.
  3. Once these fatty acids enter the cell, they aim to get into the mitochondria, which are the part of the cell that converts various things into energy.

If a fatty acid consists of 12 or fewer carbon atoms (short and medium chains), it can pass through the mitochondrial membrane without any difficulties.

Fatty acids that are 14–21 carbons (long chains, which prevail in the human body) need to be activated to pass the mitochondrial membrane.

This is when something called the carnitine shuttle comes into play. Basically, it’s a mechanism that includes three enzymes that activate long fatty acids and carnitine molecules that transport activated fatty acids into the mitochondria.

The word shuttle represents carnitine molecules that travel back and forth carrying activated fatty acids.

Carnitine plays a key role in the human ability to utilize long-chain fatty acids for energy. In the absence of carnitine, we wouldn’t be able to do it, as the deficiency of carnitine impairs this process.

No carnitine→no long-chain fatty acids in mitochondria→no ketones from these fatty acids.

Now, the question:

Should you supplement carnitine on keto?

If you are deficient in carnitine, burning fat for energy might be less efficient. The symptoms of having a lack of carnitine on keto are muscle weakness and being powerless in general.

In this case, supplementing carnitine might help.

The more interesting question is whether you should supplement carnitine if you’re not deficient.

Or, in other words:

Does supplementing extra carnitine enhance fat burning?

Is this true: more carnitine→more long-chain fatty acids in mitochondria→more ketones?

The weight of the current scientific evidence says no. Supplementing extra carnitine doesn’t directly increase fat burning.

Metaphorically, carnitine is a gas jockey, and a mitochondrion (plural mitochondria) is the engine. Carnitine can speed up the process of filling up your gas tank, but it’s the engine that is responsible for how efficiently you burn fuel.

More carnitine→long-chain fatty acids get into mitochondria faster→the same fat-burning rate in mitochondria→the same number of ketones produced.


Because the total energy spent doesn’t change.

To burn fat for energy, you need to require energy. To require energy, you need to spend energy reserves. To spend energy reserves, you need to do work. You spend the exact same amount of energy to do the exact same work, no matter whether you take carnitine or not.


Because physics, bitch.

(With a tiny tolerance based on the difference in mass after taking carnitine. I knew you would’ve said that you nerds.)

Nevertheless, supplementing carnitine can help indirectly by motivating you to move more.

I know athletes who take carnitine and then work out like crazy because they believe carnitine helps them burn more fat. And it does, by motivating them to train harder, and ultimately increasing the total energy spent.


The moral of the story:

If you overeat, supplementing carnitine won’t help you burn any fat.

If not, supplementing carnitine might help. However, if you are not deficient in carnitine, it will most likely help you indirectly by encouraging you to spend more energy.

The best supplements are L-carnitine and acetyl-L-carnitine. The former is considered to be more efficient to fuel your muscles, and the latter is believed to be more efficient for your brain.

However, they can be converted into each other. Pick whichever you like.

The Bottom Line

Summing up 10k words into a couple of succinct paragraphs is a daunting and pointless task, but I’ll do it nonetheless.

Proper nutrition is the foundation of being healthy. The notion of nutrition goes beyond carbs, protein, and fat. It includes vitamins, minerals, essential fatty acids, various molecules, and even water and oxygen.

But when big money is involved, people often try to dupe you. Use a scientific approach to separate the wheat from the chaff, or shall I say, the fish from the exogenous ketones?

P.S. If you like this guide, let us know in the comments below!

1 thought on “Keto Supplements That Work—and the Ones That Are Useless”

  1. I appreciated the insights and breakdown you provided. I’ve been keto for 4 years and am looking to fine tune my nutrition. Thank you for the chemistry class snapshots and real world speak.
    Because physics, bitch.


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