Antioxidants are often touted as powerful supplements and are thought to help prevent chronic disease and cancer, treat conditions like COPD and dementia, and even slow the aging process.
But new research from Texas A&M College of Veterinary and Biomedical Sciences (VMBS) suggests that taking high doses on a regular basis may have unexpected downsides. The study found that excessive antioxidant consumption can alter sperm DNA, increasing the likelihood of developmental differences in offspring, particularly in the formation of the face and skull.
In a study published in Frontiers of cell and developmental biologyA team led by Dr. Michael Golding used mouse models to study two widely used antioxidants, N-acetyl-L-cysteine (NAC) and selenium (Se).
Male mice treated with these antioxidants for six weeks gave birth to offspring that showed significant changes in skull and facial structure. Remarkably, the father himself had no visible health problems.
These findings raise concerns about the use of high doses of antioxidants, especially for men planning to have children.
Excess intake of antioxidants
Compounds like NAC are commonly found in supplements such as multivitamins and are often taken to reduce oxidative stress that can be caused by factors such as high alcohol intake.
Dr. Golding’s lab has long studied how paternal alcohol consumption affects offspring. Previous studies have linked heavy drinking in men to a variety of developmental problems in children, including craniofacial abnormalities. Based on this, researchers investigated whether adding NAC or Se to the diet could counteract those effects.
“We know that alcohol causes oxidative stress, and we wanted to try to counteract it by adding supplements that are known to reduce oxidative stress,” said Professor Golding, from VMBS’s Department of Veterinary Physiology and Pharmacology. “When we noticed that offspring born to males fed only NAC showed differences in their skulls and faces, this was a surprise, as this molecule is universally thought to be superior.
“When I sat down and thought about it, I realized that it makes sense. You take multivitamins to keep yourself balanced, but if what you’re taking to stay balanced is out of balance (too high a dose of antioxidants), then you’re not doing anything good.”
Previous research has already shown that overdosing on antioxidants may have drawbacks. For example, it can reduce the effectiveness of endurance training and negatively impact athletic performance.
“Sperm health is also a performance indicator, but it’s not something we consider in our daily lives,” Golding says. “If you’re taking high doses of antioxidants, your fertility may be reduced, and part of the path to poor outcomes will be the effects on your offspring.”
Facial changes may reflect brain development
One of the more unexpected findings concerned the female offspring, which showed more pronounced physical differences. These include having eyes that are close together and a small skull, characteristics that are also associated with fetal alcohol syndrome.
“There is a common wisdom in pediatrics that the face reflects the brain because the brain and face are formed at the same time,” Golding says. “When your face moves[during pregnancy]it uses cues from your brain to know where to go. If those two things don’t match up, there’s either a delay in brain development or there’s something wrong with it.
“So if you see a midline abnormality in your face, you probably have a midline abnormality in your brain,” he says. “People with these abnormalities typically have neurological conditions such as impulse control, epilepsy, and other developmental problems.”
The researchers note that it is still unknown whether the offspring in this study will experience central nervous system problems. Further research is needed to determine the long-term neurological effects.
Why balance is important when it comes to supplements
This study highlights an important point regarding nutrition and supplements. Even beneficial compounds can cause harm if taken in excess, especially without a clear medical need.
Many people regularly take high doses of supplements, including those rich in antioxidants. This is why it’s important to check the label carefully and understand the dosage of each ingredient. For example, NAC is a common ingredient in multivitamins and may be present in high levels.
“The bigger message here is that there is balance,” Golding says. “Think of yourself as a plant. If you expose a plant to the sun too long, it becomes dehydrated. If you water a plant too much, it develops root rot. But if you have the right balance of sun and water, that’s when growth begins. Health is in that realm.”
“If a vitamin is providing 1,000% of the daily recommended amount, be careful,” he said. “As long as you stay within 100%, you’ll be fine.”
