Algae, Legumes and Seeds Help Meet Iron Requirements, According to Nutrition Data

Adult iron requirements range from 8 to 18 milligrams per day, depending on age and sex, according to the National Institutes of Health Office of Dietary Supplements. Officials state that dietary sources can help meet these requirements without reliance on supplements. Standard food composition databases maintained by the U.S. Department of Agriculture (USDA) list a few foods – algae, soybeans, pumpkin seeds, lentils, and spinach – as providing significant amounts of iron per standard serving.

Iron deficiency remains a widespread concern, particularly among women and girls of reproductive age. The condition is frequently missed by standard anaemia screening tests, with ferritin measurement described as the most sensitive diagnostic test for iron deficiency. Reports state that iron deficiency produces symptoms including fatigue, dizziness, pale skin, and brittle nails.

Iron Requirements and Dietary Options

The National Institutes of Health Office of Dietary Supplements defines daily iron needs based on population groups, with adult men typically requiring 8 milligrams and premenopausal women requiring 18 milligrams per day. According to USDA Food Data Central listings, specific plant foods provide measurable quantities of this mineral when consumed in standard serving sizes.

Data from the USDA indicate that specific vegetables provide over 19 percent of the daily value for iron per cooked cup serving. The mineral operates mainly in synthesizing haemoglobin and myoglobin and in the action of the immune system. Women are described as being at the highest risk for developing iron deficiency, which decreases blood haemoglobin and haematocrit.

Iron from Algae

Data show that microalgae varieties like Chlorella vulgaris and Spirulina contain very high concentrations of iron. For example, Chlorella can have over 400 mg of iron per 100 grams of dry weight. Macroalgae (seaweeds) – marine species such as Sargassum and Gracilariopsis have demonstrated high iron concentrations ranging from 150 mg to nearly 200 mg per 100 grams.

• High absorption: Studies indicate that the iron found in certain algae is readily absorbed by the human body.
• Nutritional support: Components like chlorophyll and ascorbic acid (vitamin C) present in many algae help improve the solubility and uptake of the iron during digestion.

Iron From Legumes, Seeds, and Vegetables

Soybeans contain 8.8 milligrams of iron per 1-cup serving of cooked soybeans, according to the USDA. Raw pumpkin seeds offer 2.5 milligrams per 1-ounce serving, as listed in the USDA database. Lentils provide 7.2 milligrams per 100-gram serving, and raw spinach provides 3 milligrams per 1-cup serving, according to the same source. Eight specific vegetables provide over 19 percent of the daily value for iron per cooked cup serving, according to recent data from the USDA’s Food Data Central database, with lentils and spinach each providing more than 35 percent of the established daily value per standard serving. The report states that dietary experts recommend increasing quantity or enhancing absorption for plant-based sources to achieve adequate intake.

Factors Influencing Iron Absorption

Calcium and certain other minerals can reduce iron absorption, and officials recommend separating calcium supplements from iron-rich meals. Iron absorption is impaired when consumed at the same time as coffee (which is not recommended anyway), calcium, or other inhibitors, according to Nutrition Essentials for Nursing Practice. Consuming 50 milligrams of vitamin C with a meal, the amount found in one small orange, can increase iron absorption three to six times above normal, the same source states.

Clinical Considerations and Recommendations

Health officials advise that people with diagnosed iron deficiency should consult a healthcare provider before making dietary modifications.

The amounts listed are based on standard serving sizes and may vary with preparation and food source, according to the Office of Dietary Supplements.

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September 13, 2026