I'm interested in making a list of how to best absorb specific nutrients. Whether or not we always want to best absorb each nutrient is debatable, but I think putting this information together could be really beneficial. I started with iron and calcium. If you know some others, let me know. It will be added and appreciated.
B Vitamins: Biotin absorption is decreased by avidin, an antinutrient in raw eggs (31). Cooking denatures avidin and increases biotin bioavailability.
Beta-carotene: Beta carotene (being fat soluble) is better absorbed with fat (13). Absorption is decreased by pectin (15) and helminths, apparently (14). I guess that's a good to thing to know if you're a fan of the hygiene hypothesis and were planning to eat an intestinal parasite to cure your allergies. (perhaps add distinction between vitamin A/beta-carotene?)
Calcium: Calcium absorption is increased by vitamin D (1), enough, but not too much, magnesium (2), soluble fibers like inulin (3), and dietary protein (4). Calcium absorption is decreased by whole wheat (5), fibers in fruits and vegetables like cellulose (6,7) and oxalic acid (8).
Iron: Iron absorption is increased by vitamin C (9) and decreased by phytic acid (11), calcium (23, 24), and tannins/phenolic compounds found in things like tea, coffee, and wine (10). Vitamin A and beta carotene appear to increase non-heme iron absorption by reducing the effect of phytic acid and polyphenols (25).
Protein: Egg protein is more digestible after cooking (21). Drinking a lot of water with a meal may decrease protein digestion by diluting hydrochloric acid in the stomach. I haven't seen any hard studies on this, but Chris Kresser has said this before and I tend to trust him.
Vitamin E: Vitamin E absorption is increased by some fat (26) but not really that much is needed (27). Vitamin E absorption is decreased by naringenin (27), which is found in grapefruit. Sesamin (found in sesame seeds) increases y-tocopherol absorption (28).
Zinc: Zinc absorption appears to be increased by meat protein and decreased by phytic acid, casein, soy protein, and iron (12). (perhaps add reference to zinc/copper balance?)
So...what else helps us poop out less of the vitamins, minerals, and other nutrients we eat?
I REALLY like this question, but second the 'gut biota' and the phrase "whether or not we always want to best absorb each nutrient is debatable". Just sayin'. I'm voting organs and bone broth.
Someone please correct me if I'm wrong, but it's my understanding that the beta carotene in things like carrots and sweet potatoes are better converted to vitamin A in the presence of fat. (Or is the carotene just better absorbed in the presence of fat? Don't remember.) Maybe not a problem for people getting plenty of true vitamin A from animal sources, but for those who lean a little lower on animal fats/organs and stick to mostly veggies, could be important.
Put some butter on that sweet potato! Or olive oil/butter on the carrots. YUM.
I like this question and want to contribute. Before I do, I'm curious what kind of citation/substantiation will cut it in a list like this? In other words, who do we trust?
Can we turn to Weston A. Price Foundation, for instance, or must citations come from peer-reviewed journals or something? (I am not particularly qualified to read/interpret those....).
Also, I know that some nutrients--minerals in particular--are better absorbed in the presence of stomach acid, and/or perhaps digestive enzymes. Wondering if this could be referenced (if we can find good research supporting it). Some with poor stomach acid might not be able to absorb sufficient amounts of certain minerals, and then the effects can sort of cascade from there, affecting absorption of still other nutrients. I'll do some digging, but maybe someone who already knows will beat me to the punch.
Your body needs to metabolize calcium as well as just absorb it. Too much calcium that can't be put to use will pave the path to disc fractures and osteoporosis. You want more saturated fats, but especially vitamin K if you want your body to absorb calcium efficiently and put it to use safely.
I can tell you that the research seems to indicate that B vitamins, particularly b12, seem to be better absorbed sublingually than orally. I did a LOT of reading when I found out that I was severely deficient (combo of celiac and a b12 transportace deficiency)
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