A thousandfold healthy: current research on secondary plant substances

12th workshop of the Institute Danone Nutrition for Health eV (IDE) in cooperation with the Christian-Albrechts-Universität zu Kiel, June 11th - 12th, 2010

They make chillies hot, grapefruit bitter, color tomatoes red and make your eyes water while cutting onions: tens of thousands of plant compounds are summarized under the umbrella term "secondary plant substances", the meaning of which is often not yet fully understood. Many phytochemicals protect plants from UV light, oxygen radicals and pests. The top 30 food crops alone - which account for 90% of the world's calorie consumption - contain over 10.000 different phytochemicals. Secondary plant substances have been studied in nutritional science for around 20 years. Meanwhile, many studies also indicate the health-promoting potential of these substances in humans.

This year's journalists' workshop “A thousandfold healthy!”, Which was held on June 11th and 12th, 2010 by the Institute Danone Nutrition for Health eV in cooperation with the Institute for Human Nutrition and Food Science of the Christian-Albrechts- University of Kiel was carried out.

In the following, we present ten important facts from the presentations held. A report with scientific summaries of all lectures can be downloaded free of charge at This e-mail address is being protected from spambots To display JavaScript must be turned on! can be requested.

10 facts at a glance:

1. So far, over 10.000 secondary plant substances have been identified. They can be grouped into different chemical groups, such as carotenoids, phenolic acids, flavonoids, sulfides or phytosterols. Secondary plant substances are not only found in fruit and vegetables – they are found in all plant-based foods and therefore also in wholemeal bread, legumes and nuts, for example.
2. Secondary plant substances are usually concentrated in the skin or the outer leaves. If these are removed (e.g. by peeling apples), some of the secondary plant substances are lost.
3. Due to the large number of substances, recommendations for the daily intake of individual secondary plant substances are not very helpful. Studies suggest that the protective effects may be greatest when a broad spectrum of phytochemicals are consumed, ie many different plant-based foods are consumed. Health-promoting effects of phytochemicals from fruit and vegetables cannot be replaced by pills, capsules or powders of isolated phytochemicals.
4. The bioavailability of the various phytochemicals varies greatly and depends, among other things, on the chemical binding form of the phytochemicals. For example, numerous flavonoids are linked to a sugar molecule. In addition, the bioavailability is influenced by the preparation: carotenoids are only readily bioavailable when accompanied by fat. If cabbage vegetables are boiled (or heated in the microwave), glucosinolates can no longer develop their full effect.
5. Secondary plant substances are metabolized in the small and large intestine as well as in the liver. This results in compounds that differ significantly in their biological properties from the starting materials. However, neither the number and chemical structures of all relevant metabolites nor their molecular mechanisms of action are currently known. The metabolism of secondary plant substances by colon bacteria varies from person to person and depends on the individual intestinal flora.
6. In addition, every person can react differently to the consumption of phytochemicals simply because of their genetic make-up, ie the genotype is an important influencing factor with regard to the effect of phytochemicals.
7. Even if many of the effects of secondary plant substances have not yet been fully clarified, there is evidence that this group of substances can reduce the risk of cardiovascular diseases.
8. With regard to cancer prevention, epidemiological studies have shown an inverse correlation between the intake of some phytochemicals and the prevention of certain types of cancer. Nevertheless, there is still a considerable need for research. A high potential is attributed, among other things, to polyphenols in apples and glucosinolates in cabbage vegetables or sulfides in garlic and onions.
9. Many women of a certain age are affected by menopausal symptoms, which typically manifest themselves as hot flashes. In this context, the use of phytoestrogens, which also belong to the secondary plant substances, is often discussed. However, the effectiveness of these substances in menopausal symptoms has not yet been proven.
10. Certain secondary plant substances can also have a UV-protective effect on the skin. Good effects can be achieved, for example, by the carotenoids contained in red and yellow vegetables and fruit, such as the lycopene in tomatoes.

The Institute Danone Nutrition for Health eV

The Institute Danone Nutrition for Health eV (IDE), founded in 1992, is an independent institution that promotes selected research projects in the field of nutritional science and nutritional medicine and creates up-to-date materials for nutritional education for various target groups. Integrated into an international network, the IDE offers scientists, doctors, educators and all interested parties a platform for exchange and access to the latest scientific and medical nutritional knowledge.

Source: Kiel [ Danone ]