Food supplements: which ones are really useful?
Most are useless, a few are essential.
Dr. Léa Marin
Nutritionist, PhD
In simple terms
Vitamin D, folic acid, iron: in what situations is supplementation justified, and when are you throwing your money away?
What you need to remember
- Justified supplementation — Vitamin D**: in France, deficiency affects 40-60% of the population in winter.
- Generally useless supplementation — Multivitamins**: no demonstrated benefit on mortality or chronic diseases in well-nourished adults
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.
The words explained
Medical terms used above, in everyday language.
- Chronic
- A problem that lasts a long time, usually more than three months, and often comes back.
- Prevention
- Steps taken before a problem starts, to make it less likely.
When should you see a doctor?
- Your symptoms last more than a few weeks or keep coming back.
- They get worse quickly, or stop you doing everyday things.
- You notice sudden pain, breathing trouble, fainting or bleeding — seek urgent care.
- You already take medication and want to change anything about it.
This article explains general health information. It does not replace advice from your own doctor.
Frequently asked questions
- What is Food supplements: which ones are really useful??
- Vitamin D, folic acid, iron: in what situations is supplementation justified, and when are you throwing your money away?
- What are the main symptoms or signs of Food supplements: which ones are really useful??
- Common signs vary from person to person. The article above lists the symptoms to watch for, how they progress, and when they need medical attention.
- When should you see a doctor for Food supplements: which ones are really useful??
- See a doctor if symptoms last more than a few weeks, get worse quickly, stop you doing everyday things, or if you notice sudden pain, breathing trouble, fainting or bleeding.
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