Food supplements: which ones are really useful?

The food supplement market is worth billions of euros. However, for most healthy adults with a varied diet, they are useless. Some exceptions deserve attention.

Justified supplementation

• Vitamin D: in France, deficiency affects 40-60% of the population in winter. Recommended dose: 800-1000 IU/day from October to March, or according to blood test.
• Folic acid: 400 µg/day from the start of pregnancy planning and during the first trimester.
• Iron: only in case of documented deficiency by blood test (low ferritin). Never self-medicate.
• Vitamin B12: essential for strict vegans and elderly people (reduced absorption).
• Iodine: during pregnancy and breastfeeding if the diet is poor in seafood and dairy products.

Generally useless supplementation

• Multivitamins: no demonstrated benefit on mortality or chronic diseases in well-nourished adults
• High-dose Vitamin C: does not prevent colds
• Omega-3 in capsules: contradictory results, prefer whole fish
• Antioxidants: at high doses, could even be detrimental (increased risk of certain cancers)

A food supplement never replaces a balanced diet. Before any supplementation, a medical check-up is recommended.