Absorption and Bioavailability of Vitamins.

Vitamins are necessary for healthy metabolism in the body. Most vitamins need to come from food because the body either does not produce them or produces very little. However, how can we be sure we are absorbing our vitamins when ingested via food and supplement form. 

First it is important to understand how the absorption process of vitamins happens. There are two different types (therefore for routes) of vitamins. 

  • Water-soluble vitamins are found into the watery portions of  foods. They are absorbed directly into the bloodstream as food is broken down during digestion or as a supplement dissolves. It is hard for these vitamins to reach toxicity because they can easily be released via excretion.
  • Fat- soluble vitamins gain entry into the blood in the same way the macronutrient fat does. They are packed in micelle with fats, bile salts, and more, and then transported across the intestinal wall into the bloodstream. Therefore they are more likely to be absorbed when fat is present. 

Bioavailability is the percentage of the dose (of a nutrient or other substance) that is absorbed and able to be used by the cells for current use or stored for future use. This is why it is important to keep in mind that just because a supplement claims to contain a particular amount of a nutrient, it  doesn’t mean your body will absorb the entire amount. There are many different things that can interfere with a substance’s bioavailability, including alcohol, caffeine, competition with other foods, stress, and more. 

Some supplements contain special ingredients, or enhancers, which can improve the bioavailability of certain supplements, such as those at Klaire Labs.  Enhancers typically act in the gut to either improve solubility or reduce the amount of enzymatic breakdown.

Many substances and micronutrients can also interact with each other. For example Vitamin D, helps you absorb Calcium from food rather than taking it from bones, and Vitamin C increases iron absorption. But this is always a commensalistic relationship. This can be the quite opposite as well.  For example, oxalates found in some dark green leafy vegetables, interfere with the absorption of some minerals including Ca, Zn, ann Iron. Which is why we absorb significantly more iron from meants rather than leafy vegetables although they are both high in iron. Or even a minor overload of the mineral manganese can worsen iron deficiency.

Despite the complexity of nutrient interactions, don’t overwhelm yourself and keep it simple (: Eat a varied balanced diet,  skip fat diets (which often fail to supply necessary nutrients), and when possible try to receive your nutrients from foods before supplements. 


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