The three to watch on a vegan diet
Vitamin B12
B12 is essentially absent from unfortified plant foods. Vegans should rely on fortified foods 2–3×/day or a supplement (~25–100 mcg daily, or 2000 mcg weekly). This is the one nutrient you should not leave to chance.
Iron
Plant (non-heme) iron is less absorbable, so aim for ~1.8× the standard RDA. Pair iron foods with vitamin C (citrus, peppers) to boost absorption, and avoid tea/coffee with meals.
Omega-3 (ALA)
Plant omega-3 comes as ALA (flax, chia, walnuts, hemp). The body converts only a little to EPA/DHA, so many vegans also take an algae-oil supplement for direct DHA/EPA.
Best plant sources
| Food | Serving | B12 | Iron | ALA |
|---|---|---|---|---|
| Nutritional yeast (fortified) | 2 tbsp | 8 mcg | 1.4 mg | — |
| Fortified plant milk | 1 cup | 1.2 mcg | 0.5 mg | — |
| Fortified cereal | 1 serving | 1.5 mcg | 4.5 mg | — |
| Lentils (cooked) | 1 cup | — | 6.6 mg | — |
| Tofu (firm) | ½ cup | — | 3.4 mg | 0.3 g |
| Spinach (cooked) | 1 cup | — | 6.4 mg | — |
| Chickpeas (cooked) | 1 cup | — | 4.7 mg | — |
| Pumpkin seeds | 1 oz | — | 2.5 mg | — |
| Chia seeds | 1 tbsp | — | 1 mg | 1.9 g |
| Ground flaxseed | 1 tbsp | — | 0.4 mg | 1.6 g |
| Walnuts | 1 oz | — | 0.8 mg | 2.5 g |
| Hemp seeds | 3 tbsp | — | 2.4 mg | 2.6 g |
Common questions
How much B12 do vegans need?
The adult RDA is 2.4 mcg/day, but B12 is essentially absent from unfortified plant foods. Vegans should use fortified foods 2–3 times a day or take a supplement (around 25–100 mcg daily, or 2000 mcg weekly). It is the one nutrient not to leave to chance.
How much iron do vegans need?
Plant (non-heme) iron is less absorbable, so vegans are advised to aim for about 1.8× the standard RDA — roughly 14 mg for men and post-menopausal women, and around 32 mg for menstruating women. Pair iron-rich foods with vitamin C and avoid tea or coffee with meals.
Can vegans get enough omega-3?
Plant omega-3 comes as ALA from flax, chia, walnuts and hemp (AI: 1.6 g/day men, 1.1 g/day women). The body converts only a small amount to EPA/DHA, so many vegans add an algae-oil supplement for direct DHA/EPA.
Which nutrients should vegans actually worry about?
B12 (supplement or fortified foods — essential), iron (eat more, pair with vitamin C), omega-3 (flax/chia/walnuts plus optional algae oil), and to a lesser degree vitamin D, iodine and calcium. Protein is easy to hit with varied whole foods.
