Antioxidants are often touted as miracle cures for health and longevity. They are supposed to neutralize free radicals, prevent cell damage, and slow down the aging process. But as with many biological processes, the truth is more complex: not only a deficiency, but also an excess of antioxidants can have negative effects.
In the right amount, they protect our cells; in excessive doses, they can disrupt important cellular processes. We've examined these mechanisms in more detail here and want to give you a good overview.
What is oxidative stress?
Free radicals are produced as byproducts of metabolism, but also by environmental factors such as UV radiation, environmental toxins, and stress. While they are necessary in moderation, for example to activate the immune system, an excess can lead to (chronic) oxidative stress – a condition associated with aging processes and various diseases.
Oxidative stress occurs when the balance between free radicals and the body's antioxidant defense mechanisms is disrupted. Antioxidants are the natural antagonists of these free radicals, but their effectiveness is highly dose-dependent.
This article will tell you which antioxidants exist, how they work, and why a balanced intake is so important.
How do antioxidants work at the molecular level?
Free radicals are unstable molecules that are missing an electron. They are searching for an electron to stabilize themselves. and in doing so, they wrest it from other molecules, such as those in cell membranes or DNA.This process is called oxidation and can trigger a chain reaction that damages cell structures.
Antioxidants They counteract this by binding free radicals without becoming unstable themselves. These molecules neutralize reactive oxygen species (ROS) and reactive nitrogen species (RNS), thereby reducing oxidative stress. They donate an electron, thus ending the harmful chain reaction. One example is Vitamin C (Ascorbic acid), which neutralizes free radicals in aqueous cell environments, or Vitamin E (Tocopherol), which protects cell membranes as a fat-soluble antioxidant.
Function and signaling pathways of antioxidants
Antioxidants have effects on three different levels:
- Direct neutralization: They react with free radicals and neutralize them.
- Indirect effect: They activate cellular defense mechanisms, such as the Nrf2 signaling pathway. This regulates the expression of genes that activate antioxidant enzymes such as glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase.
- Modulation of inflammation: Antioxidants influence signaling pathways such as NF-κB, which play a role in the immune response and Inflammation play.
The importance of free radicals
Free radicals are highly reactive molecules with one or more unpaired electrons.Their name derives from their chemical nature: "free" means that they are unbound and therefore highly reactive, while "radicals" is a term for atoms or molecules with unpaired electrons. This property makes them important players in biological processes, as they can accept or donate electrons from other molecules.
Although free radicals are often portrayed as harmful, they fulfill important physiological functions:
- Signal transduction: Free radicals, such as reactive oxygen species (ROS), play a central role in cell communication. They regulate various signaling pathways, including the MAPK and NF-κB pathways, which are involved in cell growth, differentiation, and stress responses. For example, free radicals also contribute to Muscle growth after strenuous strength training.
- Immune defense: Macrophages and other immune cells use free radicals as a “weapon” against pathogens. During the so-called “oxidative burst reaction”, large amounts of ROS such as superoxide (O₂⁻) and hydrogen peroxide (H₂O₂) are released to eliminate bacteria and viruses.
- Wound healing: ROS are essential for regulating tissue regeneration. They influence angiogenesis (the formation of new blood vessels), fibroblast proliferation, and the production of Collagen, which promotes wound healing.
A certain level of oxidative stress is therefore necessary. The crucial factor is the balance between pro-oxidative and antioxidative mechanisms..
Classes of antioxidants
Antioxidants can be divided into several categories:
Vitamins
Vitamin C (Ascorbic acid): A water-soluble antioxidant that can donate electrons to neutralize free radicals. It regenerates oxidized vitamin E and supports enzymatic processes.
Vitamin E (tocopherols and tocotrienols): Fat-soluble antioxidant that protects cell membranes by preventing lipid peroxidation.
minerals
selenium: Essential component of glutathione peroxidase, an antioxidant enzyme group that breaks down peroxides.
zinc: Stabilizing element of antioxidant proteins that is involved in redox reactions and protects enzyme structures.
Secondary plant compounds:
Polyphenols: z.B. Resveratrol or CurcuminThey are also found in berries, tea and dark chocolate, act as radical scavengers in organisms at the molecular level, and activate the Nrf2 signaling pathway.
Carotenoids: These include beta-carotene, lutein, Astaxanthin and zeaxanthin, which inhibit membrane-associated oxidation reactions and thus have an effect on the skin and eyes.
Flavonoids: z.B. FisetinThey modulate inflammatory processes, influence cell communication, and have an antioxidant effect in various tissues.
Endogenous antioxidants:
Glutathion: An intracellular protective factor that reacts directly with ROS and is regenerated by glutathione peroxidase. Precursor molecules are Glycine and N-Acetylcysteine - short GlyNAC.
Superoxide dismutase: Enzyme that converts superoxide radicals into hydrogen peroxide, thus reducing oxidative damage.
Catalase: It breaks down hydrogen peroxide into water and oxygen, thus protecting against toxic peroxides.
The importance of secondary plant compounds
Secondary plant compounds Antioxidants are a diverse group of bioactive compounds that plants synthesize as a protective mechanism against environmental stress, pathogens, and herbivores. Plants are constantly exposed to factors such as UV radiation, temperature fluctuations, pest infestations, and oxidative processes. Antioxidants help them prevent cell damage and protect themselves against these influences. Among the most important antioxidant substances produced by plants are polyphenols, carotenoids, flavonoids, and vitamins such as... Vitamin C and E.
These secondary plant compounds act as a protective shield in the plant by neutralizing reactive oxygen species and minimizing oxidative damage to cell structures.
The consumption of phytochemicals as part of the human diet has diverse effects, similar to those of plants. The most important phytochemicals include:
- Flavonoids – A large group of polyphenols found in green tea, apples and onions, which possess antioxidant and anti-inflammatory properties.
- Carotenoids – Found in carrots, tomatoes and pumpkin, they contribute to the maintenance of healthy skin and eyes and act as precursors to vitamin A.
- Polyphenols Abundant in berries, dark chocolate and red wine, they are considered to support vascular health and act as free radical scavengers.
- Glucosinolate – Found in cruciferous vegetables such as broccoli, cabbage and mustard, they play a role in detoxification and cell protection.
Resveratrol intake in everyday life
Resveratrol is one of the secondary plant compounds belonging to the group of polyphenols. Particularly high concentrations are found in:
- red wineContains approximately 1.9 to 2.7 mg of resveratrol per liter.
- Red grapesContains between 50 and 100 µg of resveratrol per gram.
- peanutsContains between 0.03 and 0.14 µg of resveratrol per gram.
You may have heard that red wine is healthy despite its alcohol content – this is due to the French Paradox, which was later proven false. To reach the often-recommended daily intake of 500 mg, you would have to consume extremely large quantities.
- red wineApproximately 185 liters per day – definitely not a recommended strategy.
- Red grapesApproximately 5 kilograms per day – rather difficult to integrate into a normal diet.
- peanutsApproximately 3.6 kilograms daily – a high-calorie affair.
The role of sirtuins and their influence on oxidative stress
Sirtuins are a group of NAD-dependent enzymes and one of four Longevity pathwaysSirtuins play a central role in regulating cellular aging, metabolism, and antioxidant defense mechanisms. SIRT1, in particular, is known to reduce oxidative stress by activating the Nrf2 signaling pathway and promoting the expression of antioxidant enzymes such as superoxide dismutase (SOD) and catalase. Studies show that increased sirtuin activity can contribute to improved mitochondrial function and a reduction in DNA damage caused by oxidative stress.
Sirtuins can be activated by Fast, physical activity and certain secondary plant compounds are promoted.
When can taking antioxidants be beneficial?
Nutrient deficiency: People with limited access to antioxidant-rich foods due to dietary habits, allergies, or other factors may benefit from supplements. A doctor can determine if a deficiency exists.
High oxidative stress: People who are frequently exposed to pollution or tobacco smoke inevitably (z.BThose who are exposed to oxidative stress (e.g., due to their occupation) may benefit from additional antioxidants. However, avoiding oxidative stress should be the priority.
aging process: With increasing age, nutrient intake—and especially nutrient diversity—decreases, and the risk of chronic diseases increases. Studies suggest that a needs-based diet is crucial. It is believed that taking antioxidants could counteract certain age-related changes, however the evidence is not conclusive.
Antioxidants and sport
The use of antioxidants in connection with exercise is a controversial topic. On the one hand, antioxidants can help reduce oxidative stress caused by intense physical activity. On the other hand, recent studies show that that an excessive intake of antioxidants shortly before or after training can impair the body's adaptation processes to physical exertion.
- Possible advantages: Moderate amounts of antioxidants such as vitamins C and E, if taken at a sufficient time interval after training, can promote regeneration and reduce muscle soreness.
- Possible disadvantages: High doses could block the cellular signaling pathways necessary for adaptation to physical stress. This can weaken the training effect.
Why oxidative stress is also beneficial: During exercise, free radicals are specifically generated, which act as signaling molecules for adaptation mechanisms. They promote the production of the body's own antioxidants, increase mitochondrial biogenesis, and contribute to improved physical performance.
Optimal time to take antioxidants
Foods with antioxidants
The best absorption occurs throughout the day by eating fresh, nutrient-rich foods to ensure a consistent antioxidant defense.
Dietary supplement
Fat-soluble antioxidants (A, D, E, K): Best taken with a fatty meal to improve absorption.
Water-soluble antioxidants (Vitamin C, polyphenols, flavonoids): Can be taken at any time of day – regularity is important.
Medications && Interactions: Some antioxidants can affect the efficacy of certain medications. In this case, it is advisable to seek professional advice.
The dose makes the poison
Antioxidants are essential for health, but the right balance is crucial. Current research shows that they not only protect but can also be harmful in high doses. A varied diet is the best way to ensure an adequate intake of antioxidants.
