Selenium, zinc and iodine: small amounts that still matter

Selenium, zinc and iodine are micronutrients: the body needs only small amounts of them, but they should still be part of a varied diet. The small figures in recommendations do not mean that these substances can be completely ignored or that more is always better.

What the evidence says

The European Food Safety Authority (EFSA) sets adequate selenium intake for adults at 70 mcg per day. At the same time, the NHS in the United Kingdom provides separate reference values for people aged 19–64 years: 75 mcg of selenium per day for men and 60 mcg for women. The difference between these values shows that reference levels depend on the institution’s approach and the characteristics of the group.

For zinc, the NHS gives a reference value of about 9,5 mg per day for men aged 19–64 years and about 7 mg per day for women. Australia’s National Health and Medical Research Council and the Ministry of Health of New Zealand give different values: 14 mg per day for men and 8 mg for women. For iodine, EFSA sets adequate intake for adults at 150 mcg per day, while the same Australian and New Zealand institutions give a value of 150 mcg for adults, the same for men and women.

These values are population reference values, not personal recommendations. They do not take into account all individual circumstances, including dietary patterns, health status or other factors. When needed, personal decisions about supplements or dietary changes should be discussed with a qualified healthcare professional.

What this looks like in practice

A practical approach does not start with looking for the “perfect” figure, but with regular and varied eating. Micronutrients can come from a range of foods, so it is useful to assess the diet as a whole rather than focus on a single nutrient or one meal.

• Selenium: as a general reference, EFSA gives 70 mcg per day for adults; the NHS separately notes 75 mcg for men and 60 mcg for women aged 19–64 years.
• Zinc: the NHS gives about 9,5 mg per day for men and about 7 mg for women; Australian and New Zealand institutions give 14 mg for men and 8 mg for women.
• Iodine: EFSA and Australian and New Zealand institutions give 150 mcg per day for adults.
• Do not automatically combine several supplements with similar ingredients: first check the labels and the total amount of each substance.
• If your diet is significantly restricted or you are considering a supplement, it is best to discuss the personal choice with a healthcare professional.

What to consider

Recommendations from different institutions may not match, and this does not mean that one of them is necessarily suitable for every person. For example, the sources cited give different reference values for selenium and zinc, while the values for iodine match. It is important to always check who provided the recommendation, which group of people it was formulated for, and whether it refers to adequate intake or another type of reference level.

A small recommended amount is not a reason to take high doses “just in case”. Supplements should not replace a varied diet, and population reference values are not personal recommendations. If you have concerns about your own diet or need for supplements, seek an individual consultation with a qualified healthcare professional.

In brief

• Selenium, zinc and iodine are needed in small amounts, but they are important as part of a varied diet.
• EFSA gives 70 mcg of selenium and 150 mcg of iodine per day for adults.
• NHS reference values for selenium and zinc differ for men and women.
• Australian and New Zealand institutions give different values for zinc and 150 mcg of iodine for adults.
• All these figures are population reference values, not personal recommendations.

This is general information about nutrition and habits, not medical advice. If you are pregnant, breastfeeding, taking medication or have a chronic condition, discuss dietary changes with your doctor.