Ask the Diet Doctor: Fortified Foods
Q: Is it true that your body can't appropriately use the nutrients added to enriched and fortified foods?
A: Not at all. Your body is pretty adept at extracting and absorbing nutrients whether they are of fortified or native origin. And while oftentimes nature creates an optimal delivery vehicle and supplements or enriched foods don't provide the same level of absorption, as a general rule your body can use the nutrients you give it.
An example of nature providing an optimal nutrient delivery is heme iron. In red meat iron is part of the heme complex, and heme iron is readily absorbed. However non-heme iron from plants does not have as good of an absorption profile, and that's the case whether it's naturally occurring as in spinach or is in supplements or enriched foods.
Turning to packaged foods, milk alternatives such as soy and almond milk are not the same as milk. And while they will never match cow milk's prowess for protein, most companies do fortify their non-dairy milks with calcium, and research shows that calcium absorption from these milks is the same as from dairy milk. [Tweet this news!]
Similarly many yogurt companies have started adding prebiotic fibers to their products to make up for the fact that not all yogurts naturally contain probiotics. Your body cannot digest these dietary fibers, but the healthful bacteria in your digestive tract can use them to fuel their growth. And prebiotic fibers like inulin work just as well when naturally found in Jerusalem artichokes as when added to Greek yogurt.
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Fortified Foods and Nutrient Overload
A question that often comes up with fortification is the difference between synthetic and naturally occurring vitamins. For the most part there does not seem to be convincing evidence that synthetic vitamins are insufficient, [Tweet this fact!] but they may be harmful when the dose becomes excessive. You would not run into this situation with fortified foods but could with supplementation.
The most famous example is with beta-carotene. The Alpha-Tocopherol Beta-Carotene Cancer Prevention study and Carotene and Retinol Efficacy (CARET) Trial gave participants high doses of supplemental beta-carotene, which lead to an increase in lung cancer incidence and mortality.
The findings of these studies are often misinterpreted, and people conclude that synthetic vitamins either in supplement form or when fortified in foods are dangerous. I believe that this interpretation is missing the mark. A more accurate assessment would be that with supplements you can take in much larger amounts of a particular nutrient in a short amount of time than you could with regular food. This could lend the vitamin or mineral to act more like a drug (for better or worse) and less like a regular vitamin or mineral.