What are dietary supplements?

As the name suggests, dietary supplements are food products that supplement our regular diet. Supplements help to provide adequate nutrient amounts in the diet and boost additional demand for the body.

Vitamin and mineral mixtures were the most popular forms of nutritional supplements for many years. In recent years, a huge number of other nutrient concentrates have cropped up such as fish oil products, prebiotics and many others.

How safe are dietary supplements?

Safety is the most important aspects of legislation on dietary supplements therefore one needs to be sure that these products have no harmful effects.

In our view, the legal basis for this is well developed. The result is that any products from reputable companies and sources that are approved for sale in Europe can be regarded as safe. Nonetheless, even pharmaceutical products from dubious sources may be suspect (such products are often sold on the Internet), and this is unfortunately true for dietary supplements as well. However, this is obviously not an argument against dietary supplements in general – it’s more a reason to buy such products from reputable suppliers.


What are the benefits of dietary supplements?

A key question here is the amount of these nutrients that people ingest in their normal diet. Collection of such data is not as easy as one would wish, and the results of such studies are always somewhat inaccurate. 

Some examples of critical nutrients can be found in the table alongside. Another key question is whether there are particular population groups that don’t receive enough micro-nutrients or which have greater needs than average. Such groups are listed in the table   alongside.

Isn’t a normal diet enough?

It is often argued that the food supply is very good nowadays, and that nutritional supplements are quite unnecessary if one eats a balanced diet. We agree with this statement in principle. The fact is that in practice, not everyone eats a balanced diet. And even here there are obvious deficits – the recommendations to eat at least five servings of fruit and vegetables a day, or to eat saltwater fish at least once a week illustrate the problem. Surveys show quite clearly that only a small percentage of the population actually follows these recommendations.

Critical Nutrients

Nutrients widely undersupplied
• Vitamin D
• Folate
Nutrients partly undersupplied
• Vitamin E
• Vitamin C
• Iron (in specific risk groups)
• Iodine (supply mainly through iodized table salt)
• Zinc
• Calcium
• Magnesium
• Selenium
• Omega 3 fatty acids (EPA, DHA)

Critical foodstuffs

• Fruits and vegetables (depending on
different surveys only a maximum of
15% of the population meets the recommendation)
• Saltwater fish (rich source of omega 3 fatty acids)

Risk groups for some nutrients

  • Infants and adolescents
  • Pregnant and nursing mothers
  • Women of reproductive age
  • People on diets
  • Elderly
  • Chronically diseased people
  • Users of some drugs.
  • Smokers
  • Athletes involved in intensive activities

Risks of taking dietary supplements

These products have benefits though its important to acknowledge their negative side effects. The problem with these media reports is the one-sided and simplistic way in which they are written.

The dose makes the difference.

It is well known that certain vitamins can even have exactly the opposite effect at high doses. This may help to explain why studies of smokers who were given large quantities of beta-carotene10 reported negative results in relation to cancer risk.

Establishing “tolerable upper intake levels” (UL) for vitamins and minerals is important in this context. This means daily quantities that can be consumed regularly without any risk of harm (see the table at the bottom of the article).

These ULs are not suitable for determining the amount of a nutrient in a dietary supplement but only indicate which quantities of nutrients should not be exceeded per day. It is difficult to exceed these levels by taking dietary supplements as defined on page.

In this connection we would like to mention foods that are fortified with vitamins and minerals. By consuming this kind of foods (like fortified juices, breakfast cereals, etc.) on a regular basis and in high amounts one may easily lose control over the nutrients ingested. Here dietary supplements with clearly defined amounts of nutrients may be preferred.

Nutrients in nature are hardly ever found in pure form.

Products containing phytochemicals derived from sources such as green tea, grapes among others are sold as “botanicals”, often at doses much higher than would ever be reached in a normal diet.

This can be a problem, especially if highly concentrated extracts and high doses of single compounds
are involved. Comprehensive safety information on these substances is not yet
available, so it is still impossible to assess what effects they might have. However, several reports of adverse effects are already under discussion.

Rational dietary supplements

The table below provides an overview differentiateing between nutrients that are regarded as being generally useful, and those for which interesting and promising scientific data are available.

Wide use of iodine (in most countries covered with iodised table salt), folic acid, vitamin D, omega 3 fatty acids (fish oil and other sources) and also to some extent fruit and vegetable concentrates appears to be justified. Certain situations and specific target groups, minerals such as calcium, magnesium, iron, zinc and possibly selenium may be useful. 

Vitamins A, C, and E are well known antioxidants richly found in fruits and vegetables. There is also valid scientific evidence for substances such as pre-and probiotics, glucosamine and chondroitin, certain amino acids, plant sterols and stanols, and certain fibers.

Below are some of the examples of dietary supplements;

Vitamin A (µg)
Vitamin B1 (thiamine) (mg)
Vitamin B2 (riboflavin) (mg)
Vitamin B3 (niacin) (mg)
Vitamin B6 (pyridoxine) (mg)
Folate (µg)
Vitamin B12 (cobalamin) (µg)
Vitamin C (mg)
Vitamin D (µg / IU)
Vitamin E (mg)
Iron (mg)
Selenium (µg)
Iodine (µg)
Calcium (mg)
Magnesium (mg)
Zinc (mg)
50 / 2000

Tolerable Upper Intake Level (UL)”, Scientific Committee on Food (SCF) of the European Community and US Food and Nutrition Board (FNB) of the Institute of Medicine.

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