Nutritional Supplements ➤ What Are They & What Do I Need to Be Aware Of?

supplements in hand

A lot of people take dietary supplements; in fact, up to 50% of adults use supplements. When deciding whether to take supplements or not, many questions may arise:

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What are dietary supplements?

Dietary supplements are defined as…(1)

  • …products that supplement your general nutrition.
  • …a concentration of nutrients or other substances that have a physiological or nutritional effect.

Supplements are available  in different doses as tablets, capsules, powders, or other forms.

What supplements are available?

There are many different nutritional supplements on the market. These can be divided into the following categories:

  • Vitamins and provitamins: folic acid, vitamin C, vitamin E, B vitamins…
  • Macro and trace elements: calcium, magnesium, iron, chromium…
  • Carbohydrates: fructose and glucose composites
  • Flavonoids: polyphenols, carotene, lycopene,…
  • Plant extracts: extracts from pomegranate, cranberry, etc.
  • Enzymes: protein- and sugar-splitting enzymes, like lactase
  • Vitaminoids: vitamin-like substances like flavonoids, coenzyme Q10…
  • Amino acids and derivatives: L-arginine, L-carnitine, taurine,…
  • Mineral supplements: silica, dolomite…
  • Other dietary supplements: probiotic cultures, yeast extract…

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Do I need nutritional supplements?

If you eat a balanced diet, you probably don’t need any nutritional supplements. However, at certain times in life (e.g. growth phases, pregnancy, breastfeeding, old age), many people often need more vitamins, minerals, trace elements, and the like. That’s when it’s a good time to take supplements. Certain diseases, restrictive diets (e.g. vegan diet), food sensitivities (e.g. lactose intolerance), or high alcohol or tobacco consumption may lead to nutritional deficiencies. Supplements can have a positive influence on the symptoms of many diseases.

Good to know

Before you take dietary supplements, you should have your blood checked and discuss the results with your doctor. If you get enough nutrients through your diet, you don’t need to take supplements. Do you have a deficiency? Depending on the degree of the deficiency, your doctor can recommend different foods to include in your diet or prescribe supplements.

How much should I take?

The substances contained in supplements have a transformative function in your body: they influence your metabolism, cell division, and cell growth.

An overdose can be dangerous.(2) Overdosing on multivitamins can damage your organs. Too much vitamin A can cause skin and liver problems, too much vitamin C can upset your digestion or cause kidney stones, too much vitamin K can lessen the effect of blood thinners.


The German consumer organization Stiftung Warentest studied 35 multivitamins and found significantly higher doses than what is recommended. The maximum dose was exceeded by two to four times.(3)

This is why it’s important to consult your physician to determine the correct dosage.

Where can/should I buy nutritional supplements?

The supermarket, the drugstore, or the pharmacy – you can buy dietary supplements almost anywhere these days. But therein lies the danger: many of the substances available are poor quality or the dosage is incorrect. We should be particularly careful with herbal extracts, because they can have a negative effect on important processes in our body. Only buy supplements where you can get professional advice, like the pharmacy.


What does science say about taking supplements?

The evaluation of several studies showed that taking dietary supplements preventively does not benefit the health in any way, nor does it guarantee that you will live longer.(4) In fact, the opposite is true: as noted above, taking too much or supplementing when you don’t have a deficiency can cause health problems.(5, 6)


Dr. Otmar Höglinger Otmar is a professor of Biochemistry and head of the degree program Food Technology and Nutrition at the University of Applied Sciences Upper Austria. View all posts by Dr. Otmar Höglinger