| Food & Diet

Not All Vitamins Are Created Equal | What Is Bioavailability?

By Tyler Woodward

Everyone knows you need to eat your vitamins and minerals to fuel your body, so you can grow and develop properly  and remain healthy for years to come. Little did you know some vitamins and minerals are better than others because our body is much better able to process, absorb and utilize them. 


Types Of Vitamins & Minerals:

Types Of Vitamins


When you break it down there are really two types of vitamins:

  1. Natural Vitamins - Those made naturally from plants, animals, and bacteria
  2. Synthetic Vitamins - Those produced in a laboratory/ factory

Now, natural vitamins aren’t inherently “better” than synthetic vitamins and in some cases can actually be “better” than their natural counterparts, it all comes down to a concept known as bioavailability.

What Is Bioavailability:

Bioavailability literally means, availability to life, as in how well an organism can absorb and utilize a substance. This can apply to drugs, supplements,and the vitamins/minerals in foods. Bioavailability may seem like a simple concept, but in practice there can be large differences in absorption due to the large number of other compounds found in food. 

For example, green leafy vegetables contain a relatively large amount of calcium, but they also contain large amounts of the antinutrients phytic acid & oxalic acid which prevent the absorption of calcium. Although they may contain let’s say 100mg of calcium per serving, your body is only able to absorb between 20-40% of that calcium, equating to about 30mg. 

This concept also applies in the other direction. For instance Vitamin E increases Vitamin C absorption which increases iron absorption. Basically, the foods that you combine together in a meal or take with your supplements can play a large role in the quantity that your body absorbs.

Read More: The Importance Of Micronutrients

Minerals Bioavailability:

Minerals Availability

The best natural sources of minerals in  our diet are generally from fruit, juices, starches, meat and dairy products. This is generally for 2 reasons

  1. They lack anti-nutrients - Anti-nutrients are substances that inhibit the absorption of minerals from our food. 
  2. They come in “perfect proportions” - The concentration of minerals in other animals is often very similar to the proportions of minerals we need to absorb. For example, milk and dairy products have a very high ratio of calcium:phosphorus and also contain a lesser amount of magnesium which is necessary for calcium absorption

Vegetables, nuts, and seeds on the other hand can still supply a decent amount of minerals, but they are absorbed at a much lower rate  proportionally. Stems and leaves often contain high amounts of the antinutrients phytic acid which blocks the absorption of iron, magnesium, calcium, and zinc. They also contain oxalic acid which blocks the absorption of calcium and magnesium. Additionally, the high cellulose content of vegetables makes them extremely difficult to digest and can impair our ability to access the nutrients within them.

Read More: What Are Anti-Nutrients?

The Best Natural Mineral Sources:

Sodium - 

  • Salt
  • Seafood
  • Cured Meats
  • Dairy Products
  • Bone Broths

Potassium -

  • Avocado’s
  • Bananas
  • Citrus Fruits/Juices
  • Coconut Water/Milk
  • Potatoes & Sweet Potatoes
  • Spinach
  • Dairy Products

Calcium -

  • Dairy & Dairy products
  • Eggs Shells (can be grinded up into an awesome calcium supplement)
  • Leafy greens*
  • Nuts & Seeds*

Note -Dairy & dairy products reign supreme when it comes to calcium because of their high rate of absorption, calcium content and lack of anti-nutrients

Magnesium - 

  • Dark chocolate (and to a lesser extent milk chocolate)
  • Avocado’s
  • Nuts & Seeds*
  • Dairy
  • Coffee

Trace Minerals - 

The body also requires a very small amount of the trace minerals iron, copper, manganese, selenium, iodine, boron, molybdenum, & chromium. These foods are most commonly found in:

  • Organ Meats - like heart & liver
  • Shellfish
  • Nuts & Seeds
  • Dairy Products

Read More: The War On Micronutrients | The Battle You Never Knew You Were Fighting

Vitamins Bioavailability:

Vitamins Availability


When it comes to vitamins plants and animals use different forms of certain vitamins:

  • Plants do not produce Vitamin  A, retinol and instead rely on provitamin A or plant vitamin A beta-carotene or other types of carotenoids. Beta-carotene is very poorly absorbed compared to retinol and must be converted into retinol in the body
  • Plants only produce vitamin K1, animals require mostly K2. K1 can be converted into K2, but again only in small quantities (not enough to satisfy our needs).
  • Plants use vitamin D2 while animals use D3
  • Plants do not produce Vitamin B12 and are not good sources for the other B vitamins with a few exceptions

On the bright side, plants specifically fruits are one of the best sources of vitamin C. Vitamin C is found in relatively smaller quantities in organ meats like liver and heart, but fruits and juices are one of the best dietary sources of Vitamin C.

Last, but not least plants are often densely packed with Vitamin E, but this is a double-edged sword. Vitamin E requirements are increased the more polyunsaturated fat that are contained in any living organism in order to keep the polyunsaturated fats from oxidizing (vitamin E is a potent antioxidant). So generally, the best sources of Vitamin E also contain large amounts of the polyunsaturated fats which kind of defeats the point of consuming them for their Vitamin E quantity.

The Best Natural Vitamin Sources:

Vitamin A - 

  • Organ Meats (heart, liver, ect) are extremely densely packed with retinol
  • Muscle Meats (ruminant animals like cows and deer are the best source followed by pigs and chicken)
  • Dairy & Dairy Products (vitamin A is a fat-soluble vitamin, so remember it’s only found in the fat IE not skim milk)
  • Seafood
  • Eggs
  • Animal Fats (butter, ghee, tallow, lard, duck fat)

B-Vitamins - 

  • Organ Meats
  • Muscle Meats
  • Dairy & Dairy Products
  • Coffee (Only Vitamin B1)
  • Seafood
  • Shellfish
  • Eggs
  • Leafy Greens (Only Vitamin B9)
  • Butter (Mostly Vitamin B12)

Vitamin C

  • Organ Meats
  • Citrus Fruits
  • Melons
  • Berries
  • Peppers
  • Herbs (like parsley & thyme)
  • Certain Green Leafy Vegetables (like kale & broccoli)

Vitamin D

Most of these do not contain adequate amounts of Vitamin D3 as the majority of D3 is produced by our body endogenously

  • Seafood 
  • Animal Fats (butter, ghee, tallow, lard, duck fat)
  • Eggs Yolks
  • Beef Liver (or other ruminant animals)
  • Pasture-raised Beef
  • Pork
  • Dairy & Dairy Products

Vitamin E

As discussed before, because the foods with the most Vitamin E also have the most polyunsaturated fats, Vitamin E is a tricky one. It can be difficult to consume enough vitamin E naturally, so this is one particular vitamin that I think supplementation is justified.

  • Animal Fats (butter, ghee, tallow, lard, duck fat)
  • Organ Meats (Liver)
  • Cold-water fish (but also higher in polyunsaturated fats)

Vitamin K2 

  • Animal Fats (ghee, tallow, lard, duck fat)
  • Organ Meats
  • Muscle Meats (specifically pork & poultry)
  • Butter!
  • Dairy 
  • Fermented Cheeses (cheeses like parmesan reggiano are loaded with K2)
  • Egg Yolks
  • Fermented Plants (sauerkraut, natto)

Synthetic Vitamins & Minerals:

I think it’s always the best approach to try and maximize the number of vitamins and minerals that you can consume naturally in your diet, but it’s not always possible or easy to satisfy your micronutrients requirements through food alone. Additionally, certain foods and activities can actually increase your vitamin and mineral requirement. For example:

  • Stressors like exercise increase your electrolyte requirements including: calcium, magnesium, sodium, and potassium. 
  • The consumption of excess polyunsaturated fats increases your vitamin E requirements. 
  • Lastly, the longer you’re deficient in any vitamin or mineral it drastically increases your requirements for this vitamin and mineral. 

For these reasons, synthetic vitamins and minerals can play a huge role in correcting micronutrient deficiencies. It’s also worth noting that many supplements can have “bioidentical” forms of vitamins and meaning, meaning they’re the same chemical as found in the food. This means that they often will have identical properties to the natural vitamins if the body can absorb them. 

Here are my recommendations for the best synthetic vitamins and minerals if you can’t consume enough of the real ones in your diet:

Calcium - Calcium Carbonate

Magnesium - Magnesium taurate, glycinate, bicarbonate, gluconate

Potassium - Potassium hydroxide (cream of tartar), chloride or gluconate

Sodium - Sodium hydroxide (baking soda) or sodium chloride tablets (salt tablets)

Vitamin A - Retinyl Palmitate

B Vitamins:

B1 - Thiamine HCl

B2 - Flavin Adenine Dinucleotide (FAD),  Flavin Mononucleotide (FMN), riboflavin-5-phosphate

B3 - Niacinamide (bioidentical), preferably not niacin or inositol hexonicotinate

B5 - Pantethine (bioidentical) , pathothenate

B6 - Pyridoxal-phosphate (bioidentical)

B7 - Any 

B9 - Folate (bioidentical) or folic acid

B12 - Methylcobalamin, hydrocobalamin(be careful of cyanocobalmin)

Vitamin C - Whole Food Vitamin C (not just ascorbic acid)

Vitamin D - Vitamin D3

Vitamin E - Mixed Tocopherols including: beta, delta, gamma & alpha tocopherol

Vitamin K - Vitamin K2 MK4 as menaquinone-4, Vitamin K2 MK4 as menaquinone-7, Vitamin K1 as phyloquinone (bioidentical) or phytonadione

How To Improve Bioavailability Of Foods:

Improve Bioavailability

It’s worth noting that there are a number of ways to increase the bioavailability of certain foods to make the vitamins and minerals more accessible. This includes:

  1. Cooking (everything except fruits) - It’s theorized that one of the main sources of human intelligence came from the increased nutrient availability in cooked foods and meats
  2. Nuts & Seeds - Sprouting or soaking
  3. Grains - Fermentation (allowing to rise naturally, like sourdough)
  4. Vegetables - Cooking at a very high temperature until soft

Thermo Diet

If you want to learn how to structure your diet around consuming adequate amounts of bioavailable foods in order to increase your energy levels and improve your health, look no further than the Thermo Diet. The Thermo Diet Program teaches you everything you need to know about nutrition in order to fuel your body's micronutrient needs!


My goal in writing this article, as always, is to provide you with logically-based principles that you can use to form your own conclusions regarding any information you may come across within this subject. I really hope you found this article interesting and if you have anything to add to this article, or any comments or criticism, feel free to reach out to me on our facebook groups or on Instagram @tylerwoodward_fit. Also, please feel free to share this article with anyone that might be interested.

Thanks for reading!

Until next time… be good

~Tyler Woodward
B.S. Physiology and Neurobiology