The Power of Secondary Plant Compounds

Which substances in vegetables and fruit have a nerve-protecting effect and why

Maybe you've heard the term "secondary plant substances" before and wondered what it actually means. You often read in health guides how important these substances are for our general health - and science is actually increasingly focusing on how secondary plant substances can support not only the heart and circulatory system, but also the nervous system. In this article, we want to take a closer look at which secondary plant substances are contained in vegetables and fruit, why they are considered "nerve-friendly" and how current studies support their importance for the brain and nerves.

Plants as nutrient packages for head and body

Fruit and vegetables are certainly more to you than just colorful decorations on your plate. Perhaps you know the rule of thumb "five portions of fruit and vegetables a day" and are already trying to achieve this goal. But have you ever wondered what the reasons for this recommendation are, apart from vitamins, minerals and fiber? In fact, plant-based foods contain a whole world of bioactive substances known as secondary plant substances. These substances are neither carbohydrates nor proteins or fats, but compounds that plants naturally form to protect themselves from predators, pathogens or harmful sunlight.

Secondary plant substances (also called phytochemicals) can have amazing effects on our human organism. From antioxidant properties to anti-inflammatory and antimicrobial effects - their range of effects is broad. Many of these substances have a particularly positive effect on the nervous system: They can help to reduce stress reactions, bind free radicals and support communication between nerve cells. But which substances are these exactly, and in which foods can we find them? And which studies confirm these nerve-protecting effects?

What are secondary plant substances?

Secondary plant substances comprise a large group of chemical compounds, including polyphenols, carotenoids, phytosterols, glucosinolates and other substances. They only make up a small part of the plant mass, but are found in high concentrations in leaves, peels, etc. These substances have a protective function for the plant itself; for us humans, they open up a unique spectrum of health benefits. To help you better understand this, here is an overview of a few important groups:

1. Polyphenols : These include flavonoids (e.g. quercetin, kaempferol) and phenolic acids (e.g. chlorogenic acid).
2. Carotenoids : Beta-carotene, lutein and lycopene are probably the best known representatives of this group.
3. Glucosinolates : They are found in cruciferous vegetables such as broccoli, cabbage and cress.
4. Phytosterols : Plant substances that have a similar structure to cholesterol and are found mainly in nuts, seeds and vegetable oils.

All of these groups of substances are complex and diverse. They act partly directly as antioxidants by intercepting free radicals, and partly indirectly by activating certain enzymes in the body that protect our cells. The antioxidant and anti-inflammatory properties are particularly interesting for the nervous system, as oxidative stress and chronic inflammation are among the main risk factors for neurological disorders and diseases.

How do these substances protect the nerves?

Your brain and nervous system depend on a constant supply of energy, which means that they produce a particularly high number of metabolic products, including free radicals. These can be harmful if they occur in too high a concentration. Antioxidants - including many secondary plant substances - are able to intercept such free radicals and render them harmless before they attack our nerve cells.

Studies also indicate that certain secondary plant substances can dampen inflammatory processes that would otherwise put a strain on the nervous system. A review published in the journal Nutrients (2019) concluded that an increased intake of polyphenols (e.g. from berries) can improve cognitive functions and inhibit inflammatory reactions in the brain. According to this study, older people in particular benefited from the fact that berry polyphenols and other flavonoids stabilized certain signaling pathways in the brain and thus counteracted the aging process.

In addition, secondary plant substances can promote blood circulation, i.e. they ensure an improved supply of oxygen and nutrients to the nerve cells. Glucosinolates contained in broccoli or kale not only have a detoxifying effect, but may also support the regeneration of damaged cells. A study at the University of Illinois (2021), for example, showed that a higher intake of cruciferous vegetables (broccoli, cabbage, Brussels sprouts) was associated with a reduced risk of neurodegenerative diseases, with glucosinolates being considered an important factor.

Polyphenols: Flavonoids and Co. as a protective shield for your brain

Polyphenols are a real magic word when it comes to secondary plant substances. They can be found in vegetables, fruit, spices and even in red wine or dark chocolate (although you should of course pay attention to the sugar and alcohol content in the latter). Polyphenols are divided into several subgroups, including flavonoids. These have well-known representatives such as quercetin (e.g. in onions, apples), kaempferol (e.g. in kale, spinach) or catechins (e.g. in green tea).

Why are flavonoids so interesting for your nervous system?

They have the ability to inhibit inflammation, stabilize blood vessel walls and promote blood circulation. For the brain in particular, this means that flavonoids support a better supply of oxygen and nutrients and help reduce harmful deposits. Some flavonoids can even cross the blood-brain barrier and act directly in the brain cells. A study published in the Journal of Alzheimer's Disease (2020) suggested that higher consumption of flavonoid-rich fruits and vegetables could reduce the risk of cognitive impairment. Although the exact mechanisms are still the subject of intensive research, one thing is clear: flavonoids make a valuable contribution to maintaining our brain and nerve health.

Another study, known as the Berry Project study from Finland (2017), showed that subjects who consumed a portion of berries (blueberries, raspberries, currants) daily for eight weeks performed better on cognitive tests than the control group. The researchers suspected that the polyphenols and anthocyanins (a subgroup of flavonoids) in particular were responsible for this effect.

Carotenoids: Lutein, Lycopene and their effects on nerves and vision

Carotenoids are the substances that give many fruits and vegetables their bright colors. Just think of the orange carrot (beta-carotene), the red tomatoes (lycopene) or the yellow-green leaves of spinach, which contain lutein. Beta-carotene can be converted in the body into vitamin A, which is essential for vision and cell growth. Lycopene, found primarily in tomato products, has strong antioxidant properties and is associated with better cardiovascular protection.

But why are carotenoids good for your nerves?

On the one hand, they reduce oxidative stress in nerve tissue, and on the other hand, they influence inflammatory factors that play a role in chronic neurological diseases. A long-term study from Finland, published in the journal Neurology (2012), showed that men with high levels of lycopene in their blood had a significantly lower risk of stroke. Although this study was primarily about the cardiovascular system, the heart and brain are closely connected. Those who have healthy blood flow and fewer deposits in their vessels also benefit in terms of nerve and brain health.

Lutein is another carotenoid that plays a special role for the eyes and therefore also for the nervous system. Lutein accumulates in the retina and protects it from harmful blue light. Since vision problems and nerve disorders are sometimes closely related, this protective mechanism can indirectly support overall nerve health. For example, a study by Tufts University (2018) showed that adults who consumed more lutein-rich foods performed better on certain memory tests and suffered less from cognitive impairment.

Glucosinolates: Spicy all-rounders in cabbage, cress & co.

Glucosinolates are sulfur compounds found primarily in cruciferous vegetables such as broccoli, cauliflower, Brussels sprouts, kale, and mustard seeds or cress. If you've ever nibbled on a cress and noticed that slightly sharp, mustard-like aroma, it's precisely these glucosinolates that are causing it. In research, they are often referred to as potential cancer protectors because they activate certain detox enzymes in the body.

How do these substances benefit your nervous system?

On the one hand, they have an anti-inflammatory effect, which is beneficial for the nerves. On the other hand, glucosinolates can bind free radicals before they have a damaging effect on nerve cells. The aforementioned study by the University of Illinois (2021) found that regular consumption of broccoli, Brussels sprouts or cauliflower could apparently reduce the risk of neurodegenerative diseases. The researchers suspected that the glucosinolates made an important contribution to this by boosting the body's defense mechanisms.

Phytosterols and the support of the nervous system

Phytosterols (also called plant sterols) are compounds that have a similar structure to cholesterol, but are plant-based. They are found in particularly high concentrations in nuts, seeds and vegetable oils. They have a reputation for lowering cholesterol levels by hindering the absorption of cholesterol in the intestine.

What does it do to your nerves?

A healthy cholesterol level is definitely relevant for brain and nerve health. If cholesterol and lipid metabolism is disturbed, this can lead to deposits in the blood vessels and impair blood flow to the brain. Phytosterols can mitigate this process and thus indirectly support your nerve health. A balanced diet with sufficient nuts and seeds is therefore positive in several ways: you consume proteins, fiber and also phytosterols, which support your vascular and nervous systems.

Study situation: Polyphenols and depression, berries and cognition

While naturopathy has long had experience with the consumption of certain types of vegetables and fruits, scientific research into secondary plant substances is comparatively new. Nevertheless, more and more studies are providing evidence of their positive effects:

• Berry Project study (Finland, 2017) : This showed that people who ate a portion of berries every day performed better on cognitive tests. The experts suspected that polyphenols and anthocyanins were responsible for this effect.
• Lycopene and stroke risk (Finland, 2012) : Men with high levels of lycopene in their blood had a lower risk of stroke (published in Neurology ). Lycopene is a carotenoid found mainly in tomatoes and has antioxidant properties.
• Study by the University of Illinois (USA, 2021) : The focus was on cruciferous vegetables (broccoli, cabbage, Brussels sprouts). A connection was seen between regular consumption of these vegetables and a lower risk of neurodegenerative diseases.
• Polyphenols and depression ( Journal of Affective Disorders , 2020) : A meta-analysis suggested that a diet rich in polyphenols, such as increased consumption of fruits and vegetables, could alleviate symptoms of mild to moderate depression. Anti-inflammatory mechanisms may play a role.

Everyday strategies: How to integrate secondary plant substances

It is worth choosing a varied mix of fruits and vegetables to make the most of the variety of secondary plant substances. Here are a few simple tips:

1. Eat the colors of the rainbow : Try to choose foods of different colors every day - red (tomatoes, peppers), orange/yellow (carrots, pumpkin), green (broccoli, spinach), blue/purple (berries, eggplant). The more colorful your plate, the more different phytochemicals you absorb.
2. A few extras : Herbs and spices such as turmeric, ginger, thyme or rosemary contain high concentrations of secondary plant substances. Use them regularly when cooking to give your food flavor and an extra portion of health-promoting substances.
3. Store and prepare correctly : Some secondary plant substances are sensitive to heat, others only develop their full effect when heated. Alternating between raw and cooked vegetables is a good strategy to keep as many substances intact as possible.
4. Organic, regional, seasonal : Organically grown fruit and vegetables tend to contain higher concentrations of secondary plant substances because they have to be better protected from environmental influences. Regional and seasonal products are also fresher and contain fewer degradation products.
5. Smoothies and co .: If you don't always like chewing salad or vegetables, you can also opt for smoothies. However, make sure not to consume too much fructose at once. A green smoothie with spinach, cucumber, ginger, apple and a little lemon can be a real nutritional bomb.

Conclusion

Secondary plant substances are more than just an additional "extra" in fruits and vegetables. They form a whole world of biochemical compounds that can naturally protect your nervous system from oxidative stress, inflammation and harmful deposits. Polyphenols, carotenoids, glucosinolates and phytosterols help to keep nerve cells efficient and protect the brain from premature aging. Various studies, such as the Berry Project study (Finland, 2017) or the study by the University of Illinois (2021), support these connections and provide more and more evidence of how important a diet rich in polyphenols and carotenoids can be for our mental health.

So the next time you walk past a bowl of berries or a bunch of broccoli in the supermarket, remember that these foods contain much more than just vitamins and fiber. With every portion, you are also naturally strengthening your nerves and brain cells. And the best part is that you can achieve all of these effects without much effort and without any chemicals - simply by choosing a conscious, colorful and varied selection of fruit and vegetables.