Secondary plant substances: important for our health

Secondary plant compounds have only recently attracted the attention of science and the health industry. As their name suggests, phytochemicals are found exclusively in plants and are known to provide numerous health benefits that go beyond the basics provided by our usual nutrients.

But what exactly are phytochemicals and how can they positively influence our well-being? We answer these and other questions about phytochemicals in this article.

What are secondary plant substances?

Secondary plant substances, also known as phytonutrients, are chemical compounds produced by plants. In contrast to the primary plant substances, which are essential for the growth and development of the plant, secondary plant substances play a supporting role. For example, they serve as natural defense mechanisms against pests, UV radiation or other environmental influences.

These substances are not essential for the human body, but can still offer a variety of health benefits. The German Nutrition Society emphasizes the importance of these substances for a healthy diet and recommends consuming a variety of plant-based foods in order to benefit from the positive effects of phytochemicals [1].

What different plant substances are there?

Secondary plant substances can be divided into various groups that differ in their chemical structure and specific effects. This diversity enables them to offer a wide range of health benefits.

The best-known groups include:

Carotenoids: These colorants give fruit and vegetables their yellow, orange and red hues. Beta-carotene, a typical representative of this group, is found in carrots and pumpkins, for example. Carotenoids are not only important for plant pigmentation, but also play a role in human health by acting as antioxidants and can support eye health. [2]

Flavonoids: This group includes a variety of compounds found in almost all plants. They are known for their strong antioxidant effects and are found in high concentrations in berries, citrus fruits and green tea. Flavonoids also contribute to cardiovascular health by improving blood vessel function and exhibiting anti-inflammatory properties. [3]

Polyphenols: This group includes a variety of compounds found in fruits, vegetables, nuts and beverages such as coffee and red wine. They are known for their antioxidant and anti-inflammatory properties, which can help reduce the risk of chronic diseases [4]. Polyphenols can also positively influence the microbiota in the gut, which in turn has an effect on the immune system.

Glucosinolates: These sulphur-containing compounds are typical of cruciferous vegetables such as broccoli, cabbage and Brussels sprouts. They give these vegetables their characteristic, slightly bitter taste. When consumed, glucosinolates can be converted into biologically active compounds that can reduce the risk of cancer and promote detoxification processes in the body [5].

Essential oils: These volatile compounds are responsible for the fragrance and flavor of many herbs and spices. In addition to their sensory properties, they also have potential health benefits as they can have antimicrobial and anti-inflammatory properties. [6]

Saponins: These compounds are found in legumes and some vegetables. They can reduce cholesterol absorption in the intestine and possibly protect against certain types of cancer. [7]

Phytoestrogens: These plant compounds are similar in structure to human oestrogen. They are mainly found in soy products and flaxseed and may influence the risk of hormone-dependent cancers [8].

Sulphides: These sulphur-containing compounds are mainly found in garlic and onions. They may have antibacterial properties and may reduce the risk of cardiovascular disease. [9]

Chlorophyll: The green pigment in plants has antioxidant properties and may help detoxify the body. [10]

Are phytosterols secondary plant substances?

Yes, phytosterols are secondary plant substances. They even deserve special attention, as they can play an important role in lowering cholesterol levels.

Phytosterols, also known as plant sterols, are very similar to cholesterol in their chemical structure. This similarity is the key to their cholesterol-lowering effect. When you eat foods containing phytosterols, they compete with cholesterol in the intestine for absorption into the body. As phytosterols are less well absorbed by the body than cholesterol, this leads to reduced cholesterol absorption. [11]

Phytosterols occur naturally in many plant foods, especially in:

• Vegetable oils (e.g. sunflower oil, rapeseed oil)
• Nuts and seeds
• Wholegrain products
• Legumes
• Fruit and vegetables

In recent years, the food industry has also started to enrich certain products with phytosterols to increase their cholesterol-lowering effect. For example, you can find margarine or yogurt drinks with added phytosterols in the supermarket. The cholesterol-lowering effect of phytosterols is scientifically well documented. But beware: according to one study, excessive phytosterol levels can lead to an increase in the risk of heart attack in coronary heart patients [12].

Health-promoting effect of phytochemicals

Although phytochemicals are often only found in small quantities in our food, they can have a significant impact on our health:

Antioxidant effect: Many phytochemicals act as antioxidants. This means that they can neutralize free radicals, which can otherwise cause cell damage and contribute to premature ageing and various diseases [13].

Anti-inflammatory properties: Some phytonutrients can reduce inflammatory processes in the body. This is particularly important as chronic inflammation is associated with many diseases.

• Cancer prevention: Certain phytonutrients may be able to reduce the risk of various types of cancer.
• Cardiovascular protection: Some phytonutrients can lower cholesterol levels, regulate blood pressure and thus reduce the risk of cardiovascular disease.
• Support of the immune system: Certain phytonutrients can strengthen the function of our immune system and thus better protect us against infections.
• Protection against UV radiation: Some phytonutrients, in particular certain carotenoids, can provide natural protection against harmful UV radiation.

How to make the most of phytochemicals for your health

To prevent health risks and benefit as much as possible from the positive effects of phytochemicals, we have a few tips for you:

Eat colorful food: Different colors of fruit and vegetables often represent different phytochemicals. Red tomatoes, for example, contain lycopene, while green broccoli is rich in glucosinolates. The more colorful your plate, the more diverse the phytonutrients.

• Eat seasonally: Fruit and vegetables that are harvested at the right time of year often contain more phytonutrients.
• Gentle preparation: Many phytonutrients are sensitive to heat. Steaming or briefly sautéing can help to preserve more of these valuable compounds.
• Don't peel: In many types of fruit and vegetables, the phytochemicals are located directly under the skin. If possible, eat the peel as well.

Combine wisely: Some phytochemicals are better absorbed by the body when they are combined with certain other nutrients. For example, beta-carotene is better absorbed when consumed together with some fat.

• Go for whole grains: whole grain products contain more phytochemicals than highly processed grain products.
• Don't forget herbs and spices: these are also rich in phytochemicals and can enhance your meals not only in terms of taste but also in terms of health.

Superfoods and phytochemicals

Superfoods have attracted a lot of attention in recent years, and not without good reason. These special foods are rich in phytochemicals that have a variety of health-promoting properties. Among the best-known representatives are goji berries, acai, matcha tea and chia seeds, all of which have impressive bioactive compounds.

Goji berries are an excellent example: they contain high amounts of carotenoids, especially zeaxanthin, which is important for the health of our eyes. Acai berries also stand out as they are rich in anthocyanins - a group of flavonoids that have strong antioxidant properties and can therefore contribute to cell health. Matcha tea impresses with its high content of catechins, in particular epigallocatechin gallate (EGCG), which is known for its potential anti-cancer properties [14]. Chia seeds, on the other hand, contain lignans, which have estrogenic effects and may reduce the risk of hormone-dependent cancers. The miracle tree moringa is also a popular superfood [15].

How many phytochemicals do humans need?

There is no specific, universally valid recommendation for the daily intake of phytochemicals. The reason for this is that there is a wide variety of these compounds and their effects are complex and often synergistic. Instead, nutrition experts generally recommend following a varied and plant-based diet to benefit from the health benefits of phytochemicals.

Secondary plant substances - little helpers with a big effect

Secondary plant substances are nature's true miracle cures. Although they are only found in small quantities in our food, they can have a significant impact on our health. From lowering cholesterol levels and protecting against free radicals to supporting our immune system: the positive effects of these plant compounds are manifold and should not be ignored.

Secondary plant substances work best as part of a balanced, plant-based diet. Individually isolated substances in the form of food supplements may not have the same effect as the naturally occurring compounds in food.

The message is therefore clear: a diet rich in fruit, vegetables, wholegrain products, nuts and pulses not only prevents vitamin deficiency and provides important minerals, but also a wealth of health-promoting secondary plant substances.

By enriching your diet with a variety of plant-based foods, you are doing something good for your body and investing in your long-term health. Secondary plant substances may be small, but their effect is huge. They are another good reason to put more plants on our plates: cheers to the power of nature!

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