What are dietary supplements?
Dietary supplements are – as the name implies – products supposed to be taken in addition to your normal diet. They are available as tablets, powders or liquids, for example. They have substances in them that are also found in things you can eat, like vitamins or minerals, but in a higher concentration and often at a high dose. A dietary supplement is not necessarily made from plants such as St. John’s wort (hypericum) or garlic: it could also be an animal product, like fish oil.
Dietary supplements are over-the-counter products, which means you do not have to go to a pharmacy to buy them. They may also be part of (complementary) medical treatment. German law stipulates that they are not to have a medicinal effect – for example, lowering blood pressure or blood sugar levels. If a dietary supplement had such an effect it would have to be approved as a drug.
Dietary supplements may contain the following substances:
- vitamins and pro-vitamins (such as vitamin C, vitamin E, folic acid and beta-carotene)
- minerals and trace elements (such as calcium, magnesium, iron and zinc)
- vitamin-like substances (such as coenzyme Q10)
- fatty acids (such as omega-3 and omega-6 fatty acids)
- protein components (such as L-cysteine and L-carnitine)
- carbohydrates (such as the fiber oligofructose)
- other ingredients like brewer's yeast, algae and probiotics
Taking dietary supplements means that the body may absorb much more of these substances than would be possible by just eating a normal diet. In Germany, there are no legal limits on how much of these substances the supplements may contain, but the German Federal Institute for Risk Assessment (BfR) does issue recommendations. There are also plans to introduce limits at the European level.
In Germany, all dietary supplements must be labeled as such, and the labels must provide this information:
- amount and dose of the ingredients
- recommended daily allowance
- a reminder that dietary supplements cannot replace a balanced diet
- a warning to keep the supplements out of the reach of children
What quality and safety regulations do dietary supplements have to fulfill?
According to German law, dietary supplements are regarded as foodstuffs, not as drugs. Drugs are pharmacologically active substances that have a particular effect on the body and its functions. They are taken to relieve symptoms and illnesses, or as prevention. Dietary supplements do not have a pharmacological effect – their sole purpose is to provide the body with nutrients. For this reason, they have different quality and safety requirements than do chemical or herbal drugs.
In Germany, responsibility for the safety of dietary supplements lies – as it does with all foodstuffs – with the manufacturers and retailers. All dietary supplements must be registered with the German Federal Office of Consumer Protection and Food Safety (BVL). For dietary supplements, the authorities only record which ingredients are listed on the label. They can take samples of the products to check them.
So dietary supplements do not have to go through all of the strict tests and quality assurance processes that are required of medicines before they are sold on the market. This means that it is not always possible to be sure that all products have the same quality. For example, what is inside the bottle may not be exactly what it says on the label. It is a good idea to be especially careful when ordering products over the internet. Products ordered from abroad will not automatically conform to German food safety laws. Because other countries have different regulations, a product might contain such a large amount of a substance that it would be considered a drug in Germany. It could also contain substances in quantities exceeding the limits recommended by German regulators.
Because dietary supplements are regulated like food products rather than like medicines, they are not allowed to be advertised as substances that cure, relieve or prevent illnesses, or that are suitable for a specific therapeutic use. That is why dietary supplements will often make general claims such as "boosts your immune system," "balances your hormones" or "strengthens your joints." Most of these claims are unproven, however, and do not tell us anything about the actual health benefit of taking the product.
Do you need to take dietary supplements to stay healthy?
Someone eating a balanced diet chosen from a range of different foods will usually get all of the nutrients their body needs. You usually do not need to take extra vitamins or minerals. It may make sense to take dietary supplements on a temporary basis with the specific aim of righting a vitamin or mineral deficiency, for example.
It has been proven, however, that dietary supplements will have no effect on some illnesses. Some studies, for example, have shown that – contrary to popular belief – taking vitamin C cannot prevent a cold. Vitamin supplements do not help to prevent cancer or cardiovascular disease either.
Can dietary supplements have harmful effects?
Because manufacturers of dietary supplements are not required to provide evidence that their products are safe, harmful effects cannot always be ruled out. There are some dangerous or hazardous substances that dietary supplements are not allowed to contain. But this does not mean that vitamins or other substances might not also be harmful to your health. Research indicates that products containing vitamin A, vitamin E, or beta-carotene might increase the risk of developing certain diseases when taken over a longer period of time and at a high dose.
Some people will have strong allergic reactions to specific herbal substances. For this reason the German Federal Institute for Risk Assessment (BfR) requires all manufacturers of vitamin supplements to limit the amounts of carotenes contained in their products, for example. Also, dietary supplements may interact with medicine, which is why it is important to let your doctor know if you are regularly taking any dietary supplements if they are prescribed medication.
If you are considering taking dietary supplements, these questions may help you come to a decision:
- Why do I want to take this product?
- What other options are there for keeping me healthy?
- Would there be any disadvantages if I did not take this product?
- Is there scientific research showing that this product has a health benefit?
You can find information at the German Federal Institute for Risk Assessment (BfR).
Bjelakovic G, Nikolova D, Simonetti RG, Gluud C. Antioxidant supplements for preventing gastrointestinal cancers. Cochrane Database Syst Rev 2008; (3): CD004183.
Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Database Syst Rev 2012; (3): CD007176.
Bundesinstitut für Risikobewertung (BfR). Gesundheitliche Bewertung von Nahrungsergänzungsmitteln. Berlin: BfR.
Bundesinstitut für Risikobewertung (BfR). Bewertung der stofflichen Risiken von Lebensmitteln. Berlin: BfR.
Food and Drug Administration (FDA). Dietary supplements: What you need to know. Rockville, Maryland: US Food and Drug Administration. Juni 2016.
Michaud LB, Karpinski JP, Jones KL, Espirito J. Dietary supplements in patients with cancer: risks and key concepts, part 1. Am J Health Syst Pharm 2007; 64(4): 369-381.
Michaud LB, Karpinski JP, Jones KL, Espirito J. Dietary supplements in patients with cancer: risks and key concepts, part 2. Am J Health Syst Pharm 2007; 64(5): 467-480.
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