Do supplements actually work?

What the science says now

Do supplements work?

It depends on the supplement and on the person. Our two stories below show cases where they helped. They do not speak for every product on the shelf.

Can fish oil help your heart?

In a randomized trial, adults with high LDL cholesterol followed a heart-healthy menu. Those who also took fish oil had a bigger drop in a blood marker of heart risk called CERT2 than those on the menu alone. At 20 weeks, the score was 2.18 points lower. (Fish oil supplements plus a heart-healthy diet lowered a key heart risk score · Journal of Clinical Lipidology)

In people; trials.

The trial measured a blood marker, not heart attacks. The dose was also high: 3 grams a day of EPA and DHA. (our story · Journal of Clinical Lipidology)

In people; trials.

Can vitamin D help if your level is very low?

Researchers studied health records. People with severe deficiency (under 10 ng/mL) were more likely to die during follow-up than people with healthy levels (over 30 ng/mL). The risk was about two and a half times higher in Israel (2.57) and clearly higher in a US group (1.59). People whose supplements would be expected to raise their level by more than 10 ng/mL had lower mortality (0.72). (Very low vitamin D linked to earlier death, and supplements looked helpful · Aging Cell)

In people; observational.

Records show links, not proof that vitamin D itself made the difference.

Who oversees supplements?

The FDA says makers and distributors must evaluate the safety and labeling of their products before marketing them. The FDA can act against an adulterated or misbranded product after it reaches the market. (FDA)

Official government information.

What we don’t know yet

Our stories cover only fish oil and vitamin D. They tell us nothing about other supplements.

We don’t know if lower fish oil doses would do the same as the 3 grams used in the trial. We also don’t know if the CERT2 drop leads to fewer heart attacks, because the trial did not measure that.

For vitamin D, the strongest signal was at the very low end. The material we reviewed does not show that a supplement helps people whose levels are already healthy.

When to talk to your doctor

Ask your doctor before taking fish oil at a high dose. Ask whether a vitamin D test makes sense for you, especially if you have never been tested or your last number was under 30 ng/mL. Any supplement you take or are thinking about is worth mentioning at your next visit. Don’t start, stop or change a medicine on your own.

Talk about it at dinner

Try a simple game: “Where do we find omega-3 fats in food?” Salmon, sardines and mackerel are the fish named in our story. Let everyone pick a fish for one dinner this week, and add a vegetable or whole grain to go with it.