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SUNDAY, March 29, 2026 — Antioxidants are often seen as a good, simple way to boost health, but taking too many may come with some risks, new research suggests. A study from Texas A&M University found that high doses of certain antioxidants may affect sperm and lead to developmental changes in offspring. The research, published recently in the journal Frontiers in Cell and Developmental Biology , focused on two antioxidants: N-acetyl-L-cysteine (NAC) and selenium. Male mice given these supplements for six weeks went on to have offspring with noticeable changes in skull and facial structure. The fathers themselves appeared healthy, researchers said. The study suggests that too many antioxidants may alter sperm DNA, which could affect how offspring develop. "We know alcohol causes oxidative stress and we were looking to push back on it by adding a supplement known to lower oxidative stress," said lead researcher Dr. Michael Golding , a professor in the Department of Veterinary Physiology & Pharmacology at Texas A&M University. "When we realized that offspring born to males that had only been given NAC were displaying skull and facial differences, it was a surprise because this molecule is universally thought to be good," he added in a news release. While the results of research in animals are not always the same in people, the findings raise concerns for men who regularly take high-dose supplements, especially for those planning to have kids. Antioxidants like NAC are widely used and are often included in multivitamins. But more is not always better, experts said. "When we sat down to think it through, we realized that it makes sense — you take a multivitamin to ensure that you're in balance, but if the thing that you're taking to ensure you're in balance is unbalanced (the dose of antioxidants is too high), then you're not doing a good thing," Golding said. Previous research has also found that very high antioxidant intake can reduce the benefits of exercise and affect athletic performance. "Sperm health is another performance metric; it’s just not one that we think about in everyday life," Golding added. Researchers also noticed stronger physical changes in female offspring, including smaller skulls and closer-set eyes. These traits are oftentimes linked to conditions like fetal alcohol syndrome, the researchers said. "There's a very commonly accepted truism in pediatric medicine that the face mirrors the brain, because the brain and the face form at the same time," Golding said. "So, if you see abnormalities in the midline of the face, you're probably going to see midline abnormalities in the brain," he added. Researchers said it’s still unclear whether these changes affect brain function. The findings show that even supplements that are considered healthy can cause harm if taken in such large amounts. And many supplements contain these very high doses. "If your vitamins are providing 1,000% of the recommended daily amount, you should be cautious," he said. "If you stick to the 100% range, then you should be OK." Sources Texas A&M University, news release, March 27, 2026

A new study reveals that high doses of antioxidants—often seen as harmless or beneficial—may actually impact future generations. Male mice given common supplements like NAC produced offspring with subtle but significant facial and skull changes. Researchers believe this is tied to altered sperm DNA, even though the fathers showed no outward health issues.Antioxidants are often promoted as powerful supplements, credited with helping prevent chronic illnesses and cancer, treating conditions like COPD and dementia, and even slowing the aging process. However, new research from the Texas A&M College of Veterinary Medicine and Biomedical Sciences (VMBS) suggests that taking high doses regularly may come with unexpected downsides. The study found that excessive antioxidant intake can alter sperm DNA and may increase the likelihood of developmental differences in offspring, particularly in facial and skull formation. In research published in Frontiers in Cell and Developmental Biology, a team led by Dr. Michael Golding studied two widely used antioxidants, N-acetyl-L-cysteine (NAC) and selenium (Se), using mouse models. Male mice that received these antioxidants for six weeks produced offspring with noticeable changes in skull and facial structure. Notably, the fathers themselves showed no visible health issues. These findings raise concerns about high-dose antioxidant use, especially for men who are planning to have children. When Antioxidant Intake Becomes Excessive Compounds like NAC are commonly found in supplements, including multivitamins, and are often taken to reduce oxidative stress, which can result from factors such as heavy alcohol use. Golding's lab has long examined how a father's alcohol consumption can affect offspring. Previous work has linked heavy drinking in males to a range of developmental issues in their children, including craniofacial abnormalities. Building on this, the researchers explored whether adding NAC or Se to the diet could counteract those effects. "We know alcohol causes oxidative stress and we were looking to push back on it by adding a supplement known to lower oxidative stress," said Golding, a professor in the VMBS' Department of Veterinary Physiology and Pharmacology. "When we realized that offspring born to males that had only been given NAC were displaying skull and facial differences, it was a surprise because this molecule is universally thought to be good. "When we sat down to think it through, we realized that it makes sense -- you take a multivitamin to ensure that you're in balance, but if the thing that you're taking to ensure you're in balance is unbalanced (the dose of antioxidants is too high), then you're not doing a good thing." Previous studies have already shown that very high antioxidant intake can have drawbacks. For example, it can reduce the benefits of endurance training and negatively affect athletic performance. "Sperm health is another performance metric; it's just not one that we think about in everyday life," Golding said. "If you're taking a high dose antioxidant, you could be diminishing your reproductive fitness and part of the journey toward the bad outcome is going to be the effects on the offspring." Facial Changes May Reflect Brain Development One of the more unexpected findings involved female offspring, which showed more pronounced physical differences. These included closer-set eyes and smaller skulls, traits also associated with fetal alcohol syndrome. "There's a very commonly accepted truism in pediatric medicine that the face mirrors the brain, because the brain and the face form at the same time," Golding said. "When your face migrates (during gestation), it's using cues from your brain to know where to go, and if the two things are not aligned, there's either a delay or some kind of abnormality in brain development. "So, if you see abnormalities in the midline of the face, you're probably going to see midline abnormalities in the brain," he said. "People with these abnormalities typically have problems with impulse control, neurological conditions like epilepsy, and other developmental issues." Researchers note that it is still unclear whether the offspring in this study will experience central nervous system issues. More research is needed to determine any long-term neurological effects. Why Balance Matters With Supplements The research highlights a key point about nutrition and supplements. Even beneficial compounds can cause harm when taken in excess, particularly without a clear medical need. Many people regularly consume high-dose supplements, including those rich in antioxidants. This makes it important to carefully review labels and understand how much of each ingredient is being consumed. NAC, for example, is a common component in multivitamins and is sometimes included at elevated levels. "The larger message here is that there's a balance," Golding said. "Think of yourself as a plant -- if you stick your plant out in the sun too long, it's going to get dehydrated. If you overwater your plant, it gets root rot. But if you have the right balance of sunshine and water, that's when growth occurs. Health is in that domain. "If your vitamins are providing 1,000% of the recommended daily amount, you should be cautious," he said. "If you stick to the 100% range, then you should be OK."