252. What Is Bioavailability and Why It Matters for Your Supplements

Maybe you've heard that supplements are only good for making expensive pee,

and honestly, their critics aren't entirely wrong.

Walk into any pharmacy or health food store and you'll find shelves packed with supplements

that your body can't even use. Today we're talking about bioavailability.

It's the percentage of a substance that enters your bloodstream and becomes available for your

body to use. The supplement industry has prioritized cost and shelf stability over what actually

works in the human body, and most people have no idea. They're taking supplements based on

marketing claims without understanding the form of the ingredient determines whether it will

do anything at all. Ioleavailability isn't a marketing term. It's absolutely real and it's

rooted in biochemistry and genetics. And you understand it, you stop wasting money on supplements

that don't work, and you start giving your body what it actually needs in the form it can use.

This is actually fixable.

I'll commit to you in.

Maybe you've heard that supplements are only good for making expensive pee,

and honestly, their critics aren't entirely wrong. Walk into any pharmacy or health food store

and you'll find shelves packed with supplements that your body can't even use,

which means you're spending money on tablets and capsules, and most of it is passing right through

you unchanged. But the problem isn't supplementation itself. The issue is that most supplements are

formulated with the cheapest possible ingredients and forms your body was never designed to absorb.

I'm biohacker and human biologist Gary Breka, and you're listening to the Ultimate Human

Podcast. Today we're talking about bioavailability. I'm going to walk you through why the form of a

nutrient matters just as much as the nutrient itself and why the supplement industry has been getting

this wrong for decades. Let's start with the basics. What does bioavailability mean? It's the

percentage of a substance that enters your bloodstream and becomes available for your body to use.

That means you could take a pill with 100 milligrams of a nutrient, but only 10 percent of that

is bioavailable, your body is only getting 10 milligrams. But what happens to the other 90 milligrams?

That's the expense of urine we're talking about. This is actually fixable when the nutrient is

in a form your body can actually recognize and utilize. Your cells have specific receptors

and transport mechanisms designed to pull nutrients across the cell membrane. If a supplement

is structured in a way that fits those mechanisms, it doesn't matter how much you take.

You're holding a key that's the wrong shape for the lock. Let me give you a perfect example of this.

Creatine. It's one of the most research supplements and sports nutrition and it works, but there's

a problem. There's so many different forms of it. One of the most commonly taken is creatine

monohydrate, but it's not too highly soluble. You need about 500 milliliters of water just to dissolve

a single serving. If you've ever mixed it, you know exactly what I'm talking about. That gritty

residue at the bottom of your shaker bottle, because it doesn't dissolve well, a significant amount

of that creatine monohydrate never gets absorbed. It sits in your intestines, draws in water,

and causes bloating. If you've been feeling the creatine bloat for a long time now, check your

bottle and see if it says creatine monohydrate. Now compare that to creatine hydrochloride or creatine

HCl. This form is 41 times more water soluble than creatine monohydrate, because the solubility is

so much higher it has significantly better intestinal permeability. This means more of it actually

gets absorbed into your bloodstream or is more bioavailable. There was a study published in the

Food and Nutrition Sciences that compared these two forms head-to-head in recreational weight

lifters. Only the creatine HCl groups saw significant improvements in body composition. They reduced

body fat percentage and increased fat-free mass. The creatine monohydrate group didn't see those

changes, because the monohydrate form causes water retention and potentially weight gain.

You're holding extra water because the large amount of liquid needed to dissolve it.

Creatine hydrochloride gave them the performance benefits without the extra water weight,

and that's bioavailability at work. Same nutrient, completely different outcome based on the form.

Now let's talk about B vitamins, specifically folate and B12. This is where bioavailability

extends beyond absorption and into whether or not your genetics even allow you to use what you're

taking. Most multivitamins contain folic acid, which is cheap, stable on the shelf, and has been

added to fortified foods for decades. You've heard me harp on this for years, but there's a problem.

Folic acid is synthetic, and your body doesn't use this form directly. For folic acid to work,

your body actually has to convert it into the active form called methyl folate, or 5-MTHF,

and this is where genetics come in. There's a gene called MTHFR that stands for

methylene tetrahydrafolate reductase. This gene controls the enzyme that converts folic acid

into the usable folate, and genetic variants in MTHFR are way more common than you think.

It's estimated that roughly 46% of the population has this gene mutation. If you have this mutation,

your ability to convert folic acid is significantly impaired, or sometimes completely blocked.

So while you're taking a supplement with folic acid, you think you're getting folate,

but actually folic acid is just building up in your body. This comes with its own issues.

It can mask B12 deficiency, it can interfere with methylation pathways that are critical for

everything from detoxification to neurotransmitter production. So now, if you take methyl folate

instead, you bypass this problem. Methyl folate is already in the active form, the one that your

body can use, the one that is more bioavailable. This same principle applies to vitamin B12.

Most supplements use a form called cyanocobalamin, but cyanocobalamin is also synthetic,

and your body has to convert it into the active form called methylcobalamin. You can actually take

already active methylcobalamin so that you aren't having to process and convert the cyanocobalamin.

If you have genetic variants in the MTR or MTRR genes, your ability to convert cyanocobalamin

is very compromised. You could be taking B12 every single day and still be functionally deficient.

This might be why your B12 levels are so high in your blood because they are so low

in your cells. And remember, when our cells use it as fuel, the levels drop in our blood.

Some studies will tell you that cyanocobalamin works just fine. There was a study that compared

methylcobalamin and cyanocobalamin supplementation and found similar results in raising serum B12 levels.

And that's true if you're only measuring serum B12, but serum B12 doesn't tell you what's

happening at a cellular level. It doesn't measure whether or not that B12 is being converted into

the active form that your mitochondria need for energy production. It doesn't account for genetic

polymorphisms that affect conversion efficiency. It means that you can be taking cyanocobalamin

and have high serum B12, meaning high B12 in your blood and still be functionally deficient

in B12. Methylcobalamin skips the conversion step entirely. You're giving your body exactly what

it needs in the form your body likes. So let's talk about one more example, magnesium.

Magnesium deficiency is incredibly common and a lot of people try to supplement with magnesium

oxide or magnesium citrate. Magnesium oxide is the worst offender. Cheap, but its bioavailability

is terrible. Only 4% gets absorbed. The rest sits in your intestine and acts as a laxative.

That's why magnesium oxide is often used for constipation. It works, but that's not the kind of

absorption we're looking for when we're trying to support sleep, relaxation, or muscle recovery.

Magnesium glycinate, also called bisglycinate, is a completely different story. It's bound to

glycine, which is an amino acid that naturally promotes relaxation and enhances absorption in

the small intestine. It won't cause digestive upset and it's more bioavailable. So when you take

magnesium glycinate, especially before bed, your body can actually absorb it and use it to support

the parasympathetic nervous system, reduce muscle tension, and improve your sleep quality.

Here's what all of these examples have in common. The supplement industry has prioritized cost

and shelf stability over what actually works in the human body, and most people have no idea.

They're taking supplements based on marketing claims without understanding the form of the

ingredient determines whether it will do anything at all. If you're taking supplements right now,

look at the label. Check the forms of the ingredients. If it says folic acid,

switch to methylfolate. If it says cyanocobalamin, switch to methylcobalamin. If it says magnesium

oxide, switch to magnesium glycinate. If you're taking creatine monohydrate and dealing with bloating,

try creatine HCl. These changes will make a measurable difference in how you feel and how your

body responds. If you've enjoyed learning more about bioavailability today and you're ready to go

deeper, I want to tell you about my VIP community. When you join, you can access to tons of perks

like monthly live Q&A's, exclusive private podcast episodes specifically for my VIP members

and my brand new course called Becoming the Ultimate Human. This course is a $1,700 value,

and I give it away to my VIPs for free. It includes modules on sleep, stress, nutrition, and mindset.

Everything you need to become the ultimate human version of yourself. As we close out today,

don't forget that bioavailability isn't a marketing term. It's absolutely real and it's rooted

in biochemistry and genetics. When you understand it, you stop wasting money on supplements that don't

work and you start giving your body what it actually needs in the form it can use. What works for

one person might feel completely for another because your genetics are different. Your gut health

is different and your enzyme activity is different. So the next time someone tells you that supplements

just make expensive pee, you can tell them they're only half right. Bad supplements do exactly that,

but the right supplements in the right forms based on your individual biology change everything.

And that's just science.