Omega-3 fatty acids are mainly found in marine fish, as well as in rapeseed oils and linseed oil. They are sold as dietary supplements to be taken as capsules, too. These fatty acids are thought to have a good effect on things like fat metabolism and blood pressure. But the research findings on omega-3 fatty acids are not as expected: An analysis of research on dietary supplements involving more than 160,000 people didn't find any proof that they helped. The products didn't affect life expectancy or the risk of dying from cardiovascular diseases. Omega-6 fatty acids, which are mainly found in safflower oil, haven't been shown to have any benefits either.
What's more, an increasing number of large, reliable studies have suggested that fish oil capsules with omega-3 fatty acids could actually increase the risk of an irregular heartbeat ( atrial fibrillation).
Vitamin supplements have also been analyzed in many long-term studies involving over 300,000 participants. The vitamin products were not found to have any health benefits. In fact, some of these products even seem to reduce life expectancy.
Sometimes, people take vitamins that are believed to lower the production of “free radicals” in the body. These are substances that are said to have a harmful effect on the body’s cells. But long-term studies show that reducing free radicals doesn't improve health.
Very high doses of vitamin supplements can have side effects, too. For example, vitamin E, beta-carotene and selenium may cause constipation, diarrhea and gas. Large amounts of vitamins A and C can lead to itching.
In Germany, medical experts do not recommend using
- supplements with omega-3 fatty acids,
- vitamin supplements,
- herbal products or
- infusions that bind to metals in the body and are claimed to help against arteriosclerosis ("chelation therapy").