Who Is at Risk of Micronutrient Deficiency

A varied, adequate-calorie diet meets micronutrient needs for most people, and routine high-dose supplementation offers no proven benefit in the well-nourished. The evidence-based approach is to identify specific at-risk groups and address documented gaps:

• Vegans and strict vegetarians: vitamin B12 (must supplement or use fortified foods), plus risk for iron, zinc, calcium, vitamin D, iodine and long-chain omega-3 (EPA/DHA). The 2025–2030 Dietary Guidelines say vegetarian diets often fall short in vitamins D and E, choline and iron, and vegan diets more broadly (including B12, calcium, zinc, magnesium and protein), and advise monitoring iron, B12, vitamin D, calcium and iodine status (see Plant-Based, Vegetarian, and Vegan Diets).
• Older adults: the Dietary Guidelines note some need fewer calories but equal or greater protein, B12, vitamin D and calcium; the DRIs advise over-50s to get B12 mainly from fortified foods or supplements because 10–30% of older people malabsorb food-bound B12 (see Senior Training (Redirect → Older Adults)).
• People who may become or are pregnant: the DRIs recommend 400 mcg/day of folate from supplements or fortified foods for women able to become pregnant (to reduce neural-tube-defect risk); in pregnancy the Dietary Guidelines name iron, folate and iodine as top priorities and advise discussing a daily prenatal vitamin (see Prenatal & Postpartum (Redirect)).
• Adolescents, especially girls: higher needs for calcium and iron (menstruation), with calcium and vitamin D vital for peak bone mass (Dietary Guidelines).
• People in prolonged caloric deficit / low energy availability: broadly higher risk of shortfalls; female athletes with low energy availability are prone to iron and calcium/vitamin D problems affecting bone.
• Limited sun exposure or darker skin pigmentation: vitamin D.
• Menstruating women and endurance athletes: iron.
• People on certain medications (acid suppressants, metformin, diuretics) or with malabsorption (celiac, bariatric surgery): multiple nutrients.

When a deficiency is confirmed or strongly likely in an at-risk group, targeted supplementation is appropriate; otherwise, food-first remains the default (see Supplements — A Skeptical Note on Ineffective and Risky Products).

• Food usually suffices; target supplements to documented gaps and defined groups.
• Vegans: B12 (mandatory), plus iron, zinc, calcium, vitamin D, iodine, omega-3; DGA 2025–2030: monitor iron, B12, vitamin D, calcium, iodine.
• Older adults: protein, B12 (mainly fortified/supplement after 50), vitamin D, calcium.
• Preconception: folate 400 mcg/day from supplements/fortified food; pregnancy priorities iron, folate, iodine.
• Adolescent girls: calcium and iron.
• Calorie-restricted/low-energy-availability athletes, menstruating women, endurance athletes: iron, calcium/vitamin D.
• Low sun/darker skin: vitamin D; some meds/malabsorption: multiple.