Vitamin D, magnesium, omega-3: what makes sense
Three supplements that address genuinely common deficiencies, how much to take, and why a multivitamin usually is not needed.
Most supplements are a waste of money, but three are exceptions — not because they "build muscle", but because real deficiencies are common.
Vitamin D
- Why: at northern latitudes, from October to April the sun does not produce enough vitamin D. Deficiency is linked to lower strength, more infections and worse mood.
- Dose: 1000–2000 IU a day in winter for adults. Higher doses only after a blood test.
- When: with a meal containing fat (better absorbed).
Magnesium
- Why: lost in sweat and often low in the diet. Deficiency shows up as cramps, poor sleep and fatigue.
- Dose: 200–400 mg a day, as citrate or glycinate (oxide is poorly absorbed and loosens the bowels).
- When: in the evening; many people report better sleep.
Omega-3 (fish oil)
- Why: if you do not eat oily fish twice a week, your EPA and DHA intake is almost certainly low. Benefits for the heart and inflammation.
- Dose: 1–2 g of EPA+DHA per day (read the EPA/DHA content, not the capsule weight).
- Quality: look for purity and freshness marks; rancid oil has a strong smell.
Why a multivitamin usually is not the answer
Doses are small and spread across 25 ingredients, often in poorly absorbed forms. If you have a specific deficiency, one targeted supplement beats a colourful tablet.
Before you buy
- Get a blood test if you suspect a deficiency (D, iron, B12 for vegetarians).
- Check your medication — magnesium and omega-3 interact with some drugs (blood thinners, for example).
- Food first: oily fish, eggs, seeds, green vegetables.
The short version
- Vitamin D 1000–2000 IU in winter.
- Magnesium citrate/glycinate 200–400 mg in the evening.
- Omega-3 1–2 g EPA+DHA if you do not eat fish.
- A multivitamin is usually unnecessary.
General information, not medical advice. If you have a health condition or pain, talk to a doctor before changing how you train.
