Check out this answer from Consensus:
The efficacy of antioxidant supplements in reducing free radicals and oxidative stress in humans is still a matter of ongoing research and debate. While some studies show promising results in reducing oxidative stress markers and potentially preventing certain diseases, others highlight the inconsistent outcomes and potential risks associated with high-dose supplementation. Natural antioxidants from dietary sources are generally recommended over synthetic supplements. Further research is needed to clarify the benefits, optimal dosages, and potential risks of antioxidant supplementation.
The role of antioxidant supplements in reducing free radicals and oxidative stress in humans has been a topic of significant research interest. Free radicals are reactive molecules that can cause cellular damage, and antioxidants are thought to neutralize these harmful effects. However, the efficacy of antioxidant supplements in reducing free radicals and preventing related diseases remains a subject of debate.
Key Insights
- Mixed Evidence on Efficacy:
- Reduction in Oxidative Stress Markers:
- Some studies have demonstrated that regular supplementation with antioxidants can decrease oxidative stress markers such as malondialdehyde (MDA) and thiobarbituric acid reactive substances (TBARS) in healthy individuals3.
- Disease Prevention and Management:
- There is evidence suggesting that antioxidants may help in preventing diseases associated with oxidative stress, such as cardiovascular diseases, cancer, and neurodegenerative disorders. However, the results are not universally conclusive, and more research is needed to establish definitive benefits2 4 5 7.
- Natural vs. Synthetic Antioxidants:
- Potential Harm and Pro-Oxidant Effects:
- Gender Differences:
- Research indicates that there may be gender differences in the effectiveness of antioxidant supplements, with men potentially benefiting more from early optimization of antioxidant defenses3.
- Redox Hypothesis:
Do anti-oxidant supplements work at reducing free-radicals in humans?
Peter McCaffery has answered Unlikely
An expert from University of Aberdeen in Biochemistry
There are some different parts to answering this questions – whether they reduce free radicals and whether this is beneficial.
Anti-oxidant supplements are effective to reduce free radicals in the body (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614697/, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2684512/). You would assume this is beneficial given the damaging action of free radicals to cells and that epidemiological studies suggest that low intake or having a low serum concentration of antioxidants is associated with elevated risk of cancer. Further, foods with antioxidants are beneficial.
However, now comes the problem – large-scale controlled trials have not demonstrated consistent evidence of the action of anti-oxidants α-tocopherol or β-carotene in the prevention of cancer https://jamanetwork.com/journals/jama/fullarticle/196991
In the case of β-carotene it may even promote cancer. There are several possibilities why this may be the case. Such chemicals are not just anti-oxidants and their other actions may counteract their anti-oxidant effects. It is known that free-radicals are involved in essential signalling pathways and possible that interference with these is harmful. Foods high in antioxidants may be beneficial because of other factors other than antioxidant content, or that by having antioxidants in foods delivers them to the body in a more beneficial way e.g perhaps lower amounts over a longer period as the food is ingested is better than a daily pill.
Do anti-oxidant supplements work at reducing free-radicals in humans?
Carol Haggans has answered Likely
An expert from National Institutes of Health in Nutrition, Dietetics
Antioxidants help protect cells from the damaging effects of free radicals, which are molecules that contain an unshared electron. Free radicals damage cells and might contribute to the development of some chronic diseases such as cardiovascular disease and cancer. Several nutrients, including vitamin C, vitamin E, selenium, and beta-carotene, act as antioxidants in the body. Vitamin E, for example, helps stop the production of reactive oxygen species formed when fat undergoes oxidation. However, results from studies do not show that taking supplements containing antioxidants actually helps reduce the risk of chronic diseases. Furthermore, supplements marketed as “antioxidants” vary widely in their composition, so it’s important to read product labels to determine what ingredients they contain and at what doses. The Office of Dietary Supplements at the National Institutes of Health has fact sheets on the safety and effectiveness of dietary supplement ingredients, including many that act as antioxidants.
Do anti-oxidant supplements work at reducing free-radicals in humans?
Josh Mitteldorf has answered Near Certain
An expert from Washington University in St. Louis in Gerontology, Evolutionary Biology
Yes , anti-oxidant vitamins reduce the levels of free radicals. But no, they don’t necessarily improve health. Free radicals play a major role in signaling the body to repair itself, and without this signal, there are negative health consequences. In one of the most telling studies, a large clinical trial in Finland in the 1990s was cut short when it became clear that people taking anti-oxidant vitamins had higher cancer rates and were dying at a higher overall rate.