What Does Bioavailability Mean and Why Does it Matter?
You’ve probably heard the saying “you are what you eat.” And this is true to some degree. But a more accurate way to put it would be “you are what you absorb and utilize.” Which help explains the concept of bioavailability. Because even if you’re eating the most nutritious foods on the planet, they won’t do you any good if the nutrients are unable to enter your bloodstream in a form that your body can use.
This is also true for nutritional supplements. Under optimal circumstances, the bioavailability of proteins, fats and carbohydrates is approximately 90%. When it comes to vitamins, minerals, and phytonutrients, bioavailability can vary quite a bit. You see, there are several factors that can affect bioavailability. Some are unique to you, like your health and age. And some are universal, such as a the chemical form of a food or nutrient. Let’s take a closer look at some of these factors...
Gut Health & Bioavailability
One of the main roles of your gut is to digest your food. Essentially, this means breaking it down into nutrients that your body is designed to absorb and utilize. And this complex process requires chewing, involuntary muscle movements, stomach acid, and a cocktail of digestive enzymes among other things to function properly. Once rendered, nutrients are absorbed mainly through the lining of your small intestine where they then enter your bloodstream to be utilized by your cells.
So if your gut is compromised in any way for any reason, there may not be very many nutrients to absorb. And even if nutrients are available, your body may not be able to efficiently absorb them. Which is why those with digestive diseases often experience nutrient deficiencies. Vitamin B12 is a great example. It requires numerous reactions within the gut to occur before it can be absorbed. Many more than other nutrients. Thus, a healthy gut is essential to the bioavailability of vitamin B12. But it’s worth noting that as you age, this process naturally becomes less efficient.
Chemical Forms of Nutrients
Some nutrients naturally come in different forms. A good example is iron. Iron found in animals is referred to as heme-iron. And plant-based iron is known as non-heme iron. Heme-iron is easily absorbed through your intestinal lining. On the other hand, non-heme iron naturally has a more difficult time passing through.
It’s absorption is also more likely to be affected by certain substances, such as phytic acid found in grains and legumes. Calcium also competes for absorption with non-heme iron. However, its absorption can also be enhanced by certain nutrients, such as vitamin C. In addition, supplements can contain different chemical forms of nutrients.
And some are more bioavailable than others. Let’s take vitamin D for example. It either comes in the form of D2 or D3 (a.k.a. cholecalciferol)). Both forms must be converted into their “active” form once absorbed. But vitamin D3 has been shown to convert to its active form much faster and be 87% more effective than vitamin D2 when it comes to raising your vitamin D levels.
Fat Soluble Nutrients
Carotenoids and vitamins A, D, E, and K are known as fat-soluble nutrients. This means that eating them with fat will increase their bioavailability. This is one of the reasons why I never recommend eating a salad without dressing. Now, I don’t recommend most store-bought dressings that contain rancid “vegetable” oils, but dressings made with healthy oils, such as olive oil and avocado oil, are a big fat “yes” in my book. Of course you could just add avocado, nuts, and seeds. But who wants to eat a salad without dressing? Not me!
Phytic acid not only affects the absorption of heme. For instance, it also affects the bioavailability of calcium, zinc, and magnesium. Which is one of the many reasons I’m not a huge fan of grains, beans, and lentils. But, if your gut is healthy and you don’t experience any distress when eating them, go for it. Although, I do strongly recommend fermenting, soaking, or sprouting them to reduce the concentration of phytic acid.
Cooked versus Raw Vegetables
There’s a lot of debate about the nutritional power of raw veggies versus cooked vegetables. Yes, some nutrients are lost by cooking. This is true with vitamin C as well as some of the B vitamins since they’re water soluble. Essentially, these nutrients are lost in the cooking water. Which is why it’s generally not recommended to boil veggies. Instead, steaming, sauteing, blanching, and roasting are preferred when it comes to nutrient retention. However, the bioavailability of some nutrients is increased by cooking.
This is especially true for some phytonutrients–powerful plant nutrients that protect our cells from damage and slow down the aging process. For example, carotenoids in sweet potatoes and carrots are more bioavailable when cooked. And cooked tomatoes have higher levels of bioavailable lycopene.
Chopping, Blending, Etc.
Phytonutrients are usually found in the cell walls of plants. And depending on the health of your gut, it may be difficult for your digestive system to break the cell walls and release the nutrients trapped inside. Therefore, in some cases, smoothies, purees, and fresh veggie juices may increase the bioavailability of these phytonutrients.
This is similar when it comes to bone broth and hydrolyzed collagen, which I personally consume daily and highly recommend as an excellent source of collagen boosting amino acids (glycine and proline). Especially because these amino acids are used by your body to help heal your gut and strengthen and build new collagen for stronger joints, hair, and nails as well as firmer skin. You see, collagen is made up of very long chains of amino acids.
When consumed intact, the bioavailability is extremely low. On the other hand, bone broth and hydrolyzed collagen are made up of predigested collagen so to speak. Meaning the long chains of amino acids are broken down into much shorter chains commonly referred to as collagen peptides. Which makes them easier to digest and absorb, especially if your gut is sick.
The Bottom Line
When it comes to bioavailability, the first step is to get your gut in order. A sick gut will inevitably reduce your body’s ability to successfully digest, absorb, and utilize nutrients. And rather than bog yourself down with all the details, just remember variety is key. A variety of different foods, including bone broth and hydrolyzed collagen. And a mix of cooked and raw veggies. Variety will help ensure your body is getting all of the nutrients it needs. Finally, if you’re experiencing nutrient deficiencies, the factors I mentioned in this article related to bioavailability may be at play and should be considered.
Keep thinking Big and living BOLD!