Use dietary supplements correctly
Dietary supplements can be beneficial – but only if they do what they're intended to: fill nutritional gaps, not create excesses. A healthy body needs balance, not excess. Here are the most important basic rules, categorized according to recommendations from the German Federal Institute for Risk Assessment (BfR) and consumer protection agencies.
Supplement, not replacement
Dietary supplements are intended to fill the gaps left by an incomplete diet – for example, when dairy products or fish are scarce. Since they only ever cover individual components, they cannot replace a healthy, varied diet, but can at best be a useful supplement.
The dose makes the poison
More than 100 IU of the recommended daily intake (%) is generally unnecessary – a leaf of lettuce or a glass of orange juice already provides sufficient nutrients. According to the German Federal Institute for Risk Assessment (BfR), taking high doses of vitamins unnecessarily risks oversupply and undesirable health consequences.
Specific risks you should be aware of
Some practical examples: Additional beta-carotene can promote the development of lung cancer in smokers – the German Federal Institute for Risk Assessment (BfR) now generally advises against beta-carotene in dietary supplements. Too much vitamin A during pregnancy can impair the child's development. And a sustained vitamin D overdose can lead to kidney stones and calcification of blood vessels and organs.
Four rules of thumb for everyday life
First: Follow the package instructions exactly – never more, less is fine. Second: Do not combine products with the same ingredients. Third: Don't forget to include any fortified foods (e.g., fortified breakfast cereals or juices). Fourth: If you have a pre-existing medical condition, are pregnant, breastfeeding, or taking medication, consult your doctor or pharmacist beforehand – interactions are real.
When a supplement is really useful
There are well-documented cases where professional societies explicitly recommend targeted supplementation: Vitamin B12 In a vegan diet, supplementation is mandatory, not optional. Folic acid for women who want to have children and in early pregnancy. Vitamin D, when the body's own production via the skin largely fails in winter - ideally based on a blood test. iron However, it should only be taken if a deficiency has been diagnosed by a doctor, because too much iron is harmful.
In all other cases, the order is: first look honestly at the menu, then add targeted supplements - not the other way around.
Recognizing quality when shopping
The back of the package is what matters, not the promise on the front. Check the Dosage per daily dose and compare it to the reference intake (NRV): Reputable products stay close to 100 % – multiples of this are a warning sign, not a quality indicator. A short ingredient list without unnecessary colorings and sweeteners also speaks in favor of the product.
Be wary of health claims like "cures," "protects against disease X," or "replaces medication"—such statements are simply prohibited for dietary supplements. And: Buy from suppliers with their headquarters and legal notice in the EU, because only then do European safety regulations reliably apply.
Properly timing intake
Fat-soluble vitamins (A, D, E, K) are best taken with a meal containing some fat - a salad with oil or a few nuts will suffice. iron It works best on an empty stomach, combined with vitamin C, but away from coffee, tea and dairy products, which slow down absorption. magnesium It is better tolerated when spread throughout the day than in one large dose.
We cover this topic in detail, including times and combinations, on the page Nutrient Timing.
Caution with medications
Even „natural“ things can interact: St. John's wort It can weaken the effect of many medications - from birth control pills to blood thinners. Vitamin K can affect anticoagulants, high doses Calcium the intake of certain antibiotics and thyroid hormones.
Those who take medication regularly should briefly discuss new preparations with their doctor or pharmacy – a single sentence when picking up the prescription is often sufficient.
This information is not a substitute for individual nutritional or medical advice. Whether and which dietary supplements are suitable for you depends on your personal situation – when in doubt: get it checked out first, then take it.
