And No Myserty

I have been procrastinating about doing the research on why my iron levels are improving as a vegan out of fear that it would take me down a rabbit hole of industry-sponsored research and perpetuated misinformation from arcane sources (as my dairy products research did). My job was done for me yesterday when, at kilometer 95 of a 135 km ride, my friend Amy suggested a straightforward and, it turns out, veritable explanation. Amy has a background in nutrition, and her suggestion left me immediately feeling foolish for thinking that there needed to be anything more complicated or ground-breaking than the following: there is plenty of iron in plants. Except that this was somehow ground-breaking to me: I thought (and had been told by my doctor) that the amount of bioavailable iron in plant sources came a very distant second to that found in animal products, measure for measure.

It turns out this is not entirely true.

The RDA for iron is 15 mg/day for pre-menopausal women (or 10 mg/day for adult men and for post-menopausal women).

Here's a quick profile of the amount of iron in the foods I eat in a typical day:

As part of my homemade granola:
1/2 cup of oats 4mg
1/2 cup bran 6mg
2 TB almonds 1.3mg
2 TB pumpkin seeds 2.5mg

As part of a typical lunchtime salad:
3 cups spinach 6mg
1/4 cup dried figs 2mg
1/2 cup beats 1.4mg
4 TB sunflower seeds 2.4mg

As part of a mid-afternoon homous dip:
4 tbs tahini 2.4mg
100g chickpeas 3.1mg
1/2 cup broccoli florets 0.6mg

As part of an evening curry:
1/2 cup lentils 3.2mg
4 TB cashew nuts 2.0mg
1/2 cup potato 1.4mg
1/2 cup green beans 0.6mg

So on an average day, I am getting around 38.9mg of iron which, as those who have been paying attention so far will have noticed, is more than double my RDA. If I ate tofu (hard to find in Switzerland), I'd be getting an extra 13.2 mg per cup. As a comparison of the plant world against the animal world, 1 medium (144 g) grilled steak contains 4.3mg of iron.

One note on the bioavailabiity of plant sources of iron: in isolation, the body does not absorb plant sources of iron as well as it does the iron found in meat. However, by including foods containing vitamin C at each meal (like citrus fruits, fruit juices, berries, tomato, capsicum, broccoli and cabbage), the level of iron absorption from plant sources is increased to a level very similar to that of meat.

Having done this little tally after today's rather epic ride (I forgot to mention: the 135 kms included one 20 km 1,100m climb), I also found the scientific data I was hoping to find without too much trouble: there are indeed some (non-industry sponsored) studies that show that typical eating patterns of vegetarians indicate they actually consume more iron than meat eaters, and that vegans actually eat the most iron of all (Virginia Messina, M.P.H., R.D., and Mark Messina, Ph.D., Crown, 1996).

So there is nothing particularly mysterious about my improved iron stores. And those extra stores came in handy on that climb today.