John Myers
Antioxidants contribute to a reduced risk of disease, but may also presumably promote disease.
The essentials in brief:
- Antioxidants develop protective and health-promoting effects when they are included in a diet rich in vegetables and fruit.
- But: It has not been proven that isolated antioxidants in the form of dietary supplements protect against diseases such as arteriosclerosis, cardiovascular diseases, arthritis or cancer.
- Antioxidants in isolated form can have the opposite – negative – effect if the dosage is too high. This is especially true in the case of cancer.
What are antioxidants?
Antioxidants offer protection against so-called “free radicals”. On the one hand, these free radicals are formed by the body itself during various metabolic processes, on the other hand, they are caused by harmful external influences such as cigarette smoke, environmental toxins or UV radiation from the sun.
If there are too many free radicals in our body, so-called “oxidative stress” occurs. This is said to be one of the causes of diseases such as arteriosclerosis, cardiovascular diseases, arthritis and cancer and also causes the skin to age faster.
Oxidation can be observed, for example, in cut apples – they turn brown. Anyone who sprinkles apple slices with lemon juice can see that the antioxidant vitamin C prevents this oxidation: they retain their natural color.
As a rule, our body has a well-functioning protection system to keep free radicals in check. Antioxidants usually do not act in isolation, but in interaction with other antioxidants (antioxidant network). Individual vitamins ( B2 , vitamin C and E ) and minerals ( selenium , zinc ) are part of this system.
Depending on their origin, antioxidants can be divided into:
- Formed in the body (e.g. enzymes, hormones, metabolites)
- Externally supplied with food (e.g. vegetables, fruit, nuts)
Antioxidants from food are, for example, vitamins C and E, selenium or phytochemicals such as beta-carotene , OPC (resveratrol) , flavonoids (tea), lycopene (in tomatoes), anthocyanins (red cabbage, cherry, elderberry, chokeberry, hascap berry , maqui), zeaxanthin (spinach, peppers), chlorophyll (in spinach, lettuce, wheatgrass, spirulina ), or allicin (in garlic). The red and yellow plant pigments betalains (betacyans and betaxanthins) are also increasingly discussed. These are contained, for example, in beetroot, yellow beetroot, chard with colorful stems and cactus fruits with colorful flesh. However, little is known about their nutritional-physiological effects and bioavailability.
Overall, it is important to include plenty of plant-based foods in the diet and to select as diverse a variety as possible.
In their colorful diversity, vegetables and fruit offer a wide range of substances with an antioxidant effect. Many of these substances are in or directly under the shell – so eat the shell if possible.
What is the Antioxidant Ad?
Antioxidants neutralize so-called “free radicals” and are said to contribute to a reduced risk of disease. However, the study situation is not quite so clear.
The European Food Safety Authority has examined the study situation on the protective function of antioxidants and has described the data situation as not scientifically reliable for many substances. Only a few statements about protection against free radicals (oxidative stress) are permissible. For zinc , selenium and vitamins C , E and B2 , this includes the statement that they contribute to “protecting the cells from oxidative stress”. The sentence “Olive oil polyphenols help to protect blood lipids from oxidative stress” is also permitted.
It has not been proven that isolated antioxidants in the form of dietary supplements (or in ACE products with beta-carotene, vitamins C and E) protect against diseases such as arteriosclerosis, heart attacks, strokes, arthritis or cancer or slow down aging processes in the sense of anti-aging. There is also no evidence of a positive effect of plenty of “radical scavengers” in sport .
Companies like to advertise with a high ORAC value to prove the antioxidant effect of their product. ORAC stands for “Oxygen Radical Absorbance Capacity”, i.e. the ability to absorb oxygen radicals. However, these ORAC values are purely laboratory values that cannot be transferred to humans. There is no scientific evidence that a high ORAC value has a positive influence on the physiological processes in the human body or its health. This means that the advertising is misleading and prohibited.
What should I look out for when using antioxidants?
Some scientific studies suggest that antioxidants could also have negative – opposite – effects under certain circumstances. Some antioxidants (e.g. vitamin C , beta-carotene in addition to the desired antioxidant effect, they also have a pro-oxidative effect, i.e. they increase oxidative stress. Certain antioxidants have been shown to increase the risk of some types of cancer in some clinical studies. How antioxidants work in the body depends primarily on the amount consumed. But also the personal situation (high oxidative stress due to smoking or an illness, for example) and also whether the antioxidants are ingested in combination with other vitamins, minerals or plant substances seem to play a role. It is being discussed whether too many antioxidants could possibly even promote the development of asthma, allergies and obesity.
- As long as these potentially harmful effects have not been finally clarified, you should definitely observe the manufacturer’s consumption recommendations (and avoid excessive dosages).
- You should also tell your doctor if you are using antioxidant supplements. This is especially true if you take medication regularly.
- This is particularly important if you are suffering from cancer.
According to the German Cancer Research Center, it cannot be ruled out that antioxidants such as vitamins C, E and beta-carotene impair the effect of chemotherapy or radiotherapy. Some vitamins also lead to undesirable interactions with some cancer drugs. A number of specialist societies therefore advise cancer patients against taking high-dose antioxidants in the form of dietary supplements during tumor therapy.
In the case of deficiencies, an attempt should first be made to compensate for them with a wholesome diet instead of vitamin and mineral supplements.
Suggested maximum safe levels in dietary supplements per day:
| Vitamin A (not for pregnant women) | 0.2 milligrams (mg) |
| Vitamin C | 250 mg |
| Vitamin E | 30 mg |
| Selenium | 45 micrograms (µg) |
| Zink | 6,5 mg |
| Beta-carotene | 3,5 mg |
| Other carotenoids (lycopene, lutein, zeaxanthin, astaxanthin) | not available |
| Secondary plant substances (anthocyanins, bioflavonoids, resveratrol) | not available |
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