Body processes

Secondary Metabolism – Function, Task and Diseases

Secondary metabolism

While there is no shortage of scientific facts about primary metabolism , secondary metabolism is still largely unexplored. It refers to all metabolisms that do not directly serve to sustain life. However, the boundary between the primary and secondary metabolism is often fluid. It is particularly important in the plant world, but is also relevant for animals and humans. It is still largely unexplored in this respect, which is why this article describes its importance using plants as an example.

What is secondary metabolism?

The primary metabolism includes all processes that ensure the vital functions of an organism. The primary metabolism synthesizes vital substances such as amino acids , fats and sugars and is the same in almost all living beings.

Components of the secondary metabolism are, for example, fragrances with which the flowers of violets, lilies of the valley or roses attract their pollinators or the dyes that give fruit color or indicate their degree of ripeness.

The secondary metabolism includes all chemical compounds that are produced by the plants themselves. These are secondary plant compounds, also known as bioactive substances or antioxidants. About 200,000 such substances are known to date, but have not yet been adequately researched.

Secondary substances are the often very conspicuous characteristics of a plant, but they are dispensable for its growth and development. Secondary substances are individual and are often only found in a certain plant species. For example, pepper’s “spinning agents” are only found in tropical peppers, and morphine is only known as a secondary substance in opium poppy .

For a long time people have known a lot about the healing or poisonous effects of various plants and, based on experience gained, use them as a remedy for many diseases. How and why certain plants could heal and kill others was largely unknown until the first half of the last century. Finally, chemists also dealt with the various plant substances. In 1806, the Paderborn pharmacist Friedrich Wilhelm Sertürner was the first natural substance to isolate morphine from opium .

Only with the start of biosynthesis research after the Second World War did the knowledge of the decisive role played by secondary metabolism in the evolution of plants grow. In this respect, secondary metabolism also ensures the survival of organisms, albeit not as directly as rapid metabolism does.

function & task

Today, scientists agree that without secondary metabolism, plants would not survive. Every plant develops its survival strategy with the help of chemical agents. Predators are fought by deterrence, feeding inhibition or poison. Antibacterial or fungitoxic substances are used to prevent the spread of microbes. All of these substances have developed in the course of evolution, are constantly being adapted to changing environmental conditions and sometimes even reversed from negative to positive. For example, a plant whose toxic barrier has been overcome by an insect can become its preferred food plant or serve as an ovipositor, thereby developing into a special niche for life. 

Many studies have shown that the secondary metabolites produced in specialized plant cell types have an influence on a large number of human metabolic processes. Although they are not among the essential nutrients , a wide variety of health-promoting effects are attributed to them. For this reason in particular, the German Society and all health insurance companies have been recommending a generous consumption of vegetables and fruit , legumes and nuts as well as whole grain products for years. The ingredients of vegetables and fruit are important for us humans because they protect against free radicals with their secondary plant ingredients, the antioxidants .

So far, research has focused on about 30 of the world’s most commonly consumed plants and their phytonutrients. Each plant contains a limited but large number of different substances, for example the apple with 200 to 300 and the tomato with 300 to 350 substances. Compared to fruit, vegetables contain more vitamins and phytochemicals. The concentration in the shell or in the kernels is particularly high.

Diseases & Ailments

If people consume too few of the secondary plant metabolites, deficiency symptoms can occur. The substances have a preventive effect in this respect. In the case of existing problems, the intake of the secondary metabolites can alleviate symptoms and diseases. 

A well-known subgroup of polyphenols are anthocyanins. They are mainly found in blue, purple, red, or blue-black fruits and vegetables. They are contained in many dark blue or red cherries and berries, in aubergines , in red onions and also in red cabbage . Anthocyanins are particularly protective against direct sunlight. Anthocyanins are considered to be particularly effective antioxidants. They protect our cells , for example, from inflammation and degeneration ( cancer ).

Astaxanthin is a particularly effective antioxidant. It belongs to the group of carotenoids and gives tomatoes and carrots their red colour. Astaxanthin is important for us humans as a source of strength and to protect the skin , joints and especially the eyes (macula) from free radicals.

The seeds of grapes contain OPC (oligomeric procyanidins) resveratol and quercetin. All three also belong to the polyphenols. OPC is probably the most powerful known antioxidant. When it comes to the skin, OPC is considered an anti-aging wonder drug, it can reduce wrinkles and accelerate wound healing . It protects the heart , blood vessels and eyes. Resveratol and quercetin also help fight cancer, lower blood pressure and regulate cholesterol .

The pomegranate has always been considered a religious symbol of fertility . Today this special fruit is of great scientific interest. Due to its special biochemical composition, the pomegranate is considered to be the best known source of antioxidants to date. It not only has a particularly high concentration of vitamin C , potassium and vitamin B5 (pantothenic acid), but also contains many polyphenols and tannins that protect against diseases. Its positive effect on prostate and breast cancer is currently being intensively researched .

Phytoestrogens include lignans (components of flaxseed ). They are also said to have an anti-cancer effect.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.