Iron in Plant Based Foods

The RDA is 8 mg/day for adult men and post-menopausal women, 18 mg/day for premenopausal women, and 27 mg/day during pregnancy. For plant based eaters, the National Academies of Medicine recommend consuming 1.8× the standard RDA to account for lower bioavailability — roughly 14 mg/day for men and ~32 mg/day for premenopausal women. A cup of cooked lentils (6.6 mg), a handful of pumpkin seeds (~2.5 mg), and two slices of fortified bread (~3–4 mg) together with vitamin C-rich foods can meaningfully close these gaps.

All iron in plant foods is non-heme iron. Heme iron comes exclusively from haemoglobin and myoglobin in meat, poultry, and fish, and is absorbed at 15–35%. Non-heme iron absorption ranges from just 2–20% and is highly dependent on the presence of absorption enhancers (especially vitamin C) and inhibitors (phytates, polyphenols, calcium). While the lower base absorption rate requires attention, it is also more tightly regulated — the body upregulates non-heme absorption when iron stores are low.

Yes. Well-planned plant based diets reliably meet iron needs when emphasising legumes, seeds, and whole grains, and when pairing these foods with vitamin C. Research shows that vegans and vegetarians do not have higher rates of iron deficiency anaemia than omnivores when diet quality is similar. The body's adaptive response — upregulating non-heme absorption when stores are low — plays an important compensatory role. Premenopausal women with heavy periods are the highest-risk group and should monitor iron status through regular blood tests regardless of diet.

The most evidence-based strategy: pair every iron-rich meal with a vitamin C source. As little as 25–75 mg of vitamin C (half a kiwi, a small bell pepper, a squeeze of lemon) can increase non-heme iron absorption 3–6×. Avoid tea, coffee, and calcium supplements within one hour of iron-rich meals — polyphenols and calcium are the two biggest inhibitors. Soaking, sprouting, or fermenting legumes and grains reduces phytate content significantly, improving effective iron delivery. Cooking in a cast iron pan also leaches small amounts of iron into food.

Spinach is frequently cited for iron (~2.7 mg/100g raw) but it is actually a poor iron source due to its very high oxalate content. Oxalic acid binds iron into insoluble complexes, reducing absorption to roughly 1–2% — far below the already modest baseline for non-heme iron. Legumes, seeds, and tofu are dramatically better plant based iron sources. Cooked spinach has somewhat lower oxalate, but even then it underperforms compared to lentils or pumpkin seeds of the same weight.

The main inhibitors of non-heme iron absorption are: phytic acid (found in whole grains, bran, and legumes), polyphenols in tea, coffee, red wine, and cocoa, calcium from dairy or supplements, and oxalic acid in spinach, chard, and beet greens. Avoid tea and coffee within one hour before or after iron-rich meals — even a single cup of tea with a meal can reduce iron absorption by 60–70%. Soaking and cooking legumes substantially reduces their phytate burden.