Food Freedom Friday Edition 162 - You Are What You Absorb

The importance and significance of nutrient bioavailability

You have probably heard the saying ‘you are what you eat.’ This is true to some extent, but to put it more accurately, ‘you are what you absorb and utilize.’ This explains the concept of bioavailability.

You could be eating the most nutritious foods available, but they will do you little 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 substantially.

There are several factors that can affect bioavailability. Some are unique to you, like your health, genetic dispositions and age. Others are universal, such as the biological or chemical form of a food or nutrient.

Some of the factors affecting bioavailability include:

Gut Health & Bioavailability

One of the main roles of your gut is to break down and digest your food. Essentially, this means skillfully partitioning it into nutrients that your body is designed to absorb and utilize. This complex process requires processed including chewing, involuntary muscle movements, stomach acid, and a cocktail of digestive enzymes to function optimally and efficiently.

Once rendered, nutrients are predominantly absorbed through the lining of your small intestine where they then enter your bloodstream to be utilized by your cells.

If your gut is compromised in any way, for any reason, there may not be very many nutrients to absorb. Furthermore, even if nutrients are available, your body may not be able to efficiently absorb them. This explains why those with digestive diseases often experience nutrient deficiencies. To add to this concern, the resilience and efficiency of the digestive tract diminishes with age.

Vitamin B12 is a great example. It requires numerous reactions within the gut to occur before it can be absorbed, many more than most other nutrients. A healthy, well-functioning gut is essential to the bioavailability of vitamin B12.

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. Its absorption is also more likely to be affected by certain substances, such as the 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. Some are more bioavailable than others. Vitamin D provides a great example: It can come in either in the form of D2 or D3 (also known cholecalciferol)). Both forms must be converted into their ‘active’ form once absorbed. 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 they need to be bound to a fat in order to be absorbed. Eating them with fat will increase their bioavailability. This is one of the reasons I like to recommend eating a salad with a healthy-fat-based dressing.

Most store-bought dressings contain unhealthy ‘vegetable’ or crop-based oils, but dressings made with healthy oils, such as olive oil and avocado oil, are a supportive of and necessary for fat-soluble nutrient absorption. Another option would be to include high fat foods like avocado, olives and some nuts, and seeds.

Phytic Acid

Phytic acid not only affects the absorption of heme-iron. This anti-nutrient also impacts the bioavailability of calcium, zinc, and magnesium. This is one of the many reasons I do not encourage the consumption of grains and many legumes. If your gut is healthy and you do not experience any distress when eating them, you may want to incorporate them as part of your nutrition plan although, I do strongly recommend fermenting, soaking, or sprouting them to reduce the concentration of phytic acid.

Cooked Vs. Raw Vegetables

There is much debate arund the nutritional impact of raw versus cooked vegetables.

It is a fact that some nutrients are lost by cooking. This holds true for vitamin C as well as some of the B vitamins since these are water soluble and are lost in the cooking water. This is the reason I discourage boiling vegetables in water. Instead, steaming, sautéing, blanching, and roasting are preferred when it comes to nutrient retention.

On the other hand, the bioavailability of some nutrients is increased by cooking. This is especially true for some phytonutrients, the powerful plant nutrients that protect your 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 and Pulverizing

Phytonutrients are usually found in the cell walls of plants. Depending on the health and integrity 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 vegetable juices may increase the bioavailability of these phytonutrients.

This is similar when it comes to a slow simmered bone broth and  supplemental hydrolyzed collagen. The nutrients have been released by the cooking and processing method making these both excellent sources of the collagen boosting amino acids glycine and proline). 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.

Collagen is made up of 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 or broken-down collagen. This means that the long chains of amino acids are separated into much shorter chains commonly referred to as collagen peptides. This makes them easier to digest and absorb, especially if your gut is compromised or inflamed.

In Conclusion

When it comes to bioavailability, the first step is to get your gut in order. An ill-functioning gut will inevitably reduce your body’s ability to successfully digest, absorb, and utilize nutrients.

There is no need to feel overwhelmed by the details – it is simply variety that is key. A diverse array of foods, including bone broth and hydrolyzed collagen along with a mix of cooked and raw vegetables will help ensure your body is getting all of the nutrients it needs.

Finally, if you are or suspect you may be experiencing nutrient deficiencies, these factors related to bioavailability may be at play and should be considered.

Michal Ofer