Iron in Plant-Based Foods

The richest practical plant-based iron sources are: pumpkin seeds (~8.8 mg/100g raw), tahini (~8.9 mg/100g), hemp seeds (~7.9 mg/100g), dried lentils (~7.5 mg/100g uncooked), dried beans (6–9 mg/100g uncooked), tofu (~2.7 mg/100g), tempeh (~2.7 mg/100g), edamame (~2.3 mg/100g), and blackstrap molasses (~4.7 mg/100g). Dried herbs and spices are exceptionally high per 100g but used in small quantities. Fortified cereals can also be very high.

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.

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.

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 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.

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.

Iron deficiency progresses in stages. The final stage — iron deficiency anaemia — presents as: fatigue and weakness, shortness of breath during activity, pale skin and pale lower eyelids, cold hands and feet, dizziness or lightheadedness, brittle or spoon-shaped nails (koilonychia), and restless legs syndrome. Pica (craving non-food items like ice, clay, or dirt) is a classic but often overlooked symptom. Cognitive impairment and reduced exercise tolerance can occur before anaemia fully develops. Diagnosis requires blood tests — ferritin is the most sensitive early marker.

Yes — vitamin C is the most powerful known enhancer of non-heme iron absorption. It reduces ferric Fe³⁺ to the more absorbable ferrous Fe²⁺ and forms soluble iron-ascorbate complexes. A large body of controlled research shows: 25–75 mg of vitamin C doubles to triples absorption, and 150 mg can increase it by 4–6×. Practical examples: half a bell pepper (~100 mg vitamin C) with lentil soup, lemon juice squeezed on beans, or a kiwi fruit with a meal containing tofu or seeds. This is one of the highest-leverage single dietary interventions for plant-based iron status.

Most plant-based eaters with a well-planned, varied diet do not need an iron supplement. Supplementation is appropriate for: premenopausal women with heavy menstrual losses, pregnant individuals (regardless of diet), endurance athletes prone to haemolysis-related losses, and anyone with confirmed deficiency (low ferritin or haemoglobin). If supplementing, iron bisglycinate or ferrous gluconate are gentler on the digestive system than ferrous sulphate. Never supplement without first confirming deficiency — excess iron generates free radicals and carries cardiovascular risk.

Boiling causes modest iron leaching into cooking water, but the net effect on plant-based iron nutrition is often positive — because cooking dramatically reduces phytate content in legumes and grains, the main inhibitor of iron absorption. Cooked lentils and beans are much better effective iron sources than raw because their phytate is substantially reduced. Fermentation (sourdough), sprouting, and soaking achieve similar phytate reductions. Cooking in cast iron pans can add meaningful amounts of iron to food, particularly acidic or moist dishes like tomato sauce.

Yes — and virtually all pregnant women need supplemental iron regardless of diet, since food iron alone rarely meets the dramatically increased pregnancy RDA of 27 mg/day. Pregnant plant-based eaters should: prioritise iron-rich foods (lentils, tofu, fortified cereals), pair every iron-rich meal with vitamin C, and avoid tea or coffee with meals. Iron bisglycinate is the recommended supplement form — equivalent efficacy with significantly lower rates of GI side effects compared to ferrous sulphate. Monitor status through regular ferritin tests throughout pregnancy.