Your soda or happy hour habit could be messing with your hair health.
That’s according to a new review of nearly 20 studies, which found a link between drinking alcohol and sugary beverages and an increased risk of hair loss. On the flip side, higher intakes of vitamin D and iron were associated with the opposite—greater hair growth.
That finding isn’t entirely surprising, said Julia Zumpano, RD, a registered dietitian based at the Cleveland Clinic. “Nutrient intake plays an essential role in hair loss, as indicated in this review,” she told Health.
Still, she added, the research helps paint a clearer picture of exactly how—and which—nutrients are most important for healthier hair.
For the new review, researchers analyzed 17 studies from around the world, including a total 61,332 people between the ages of 7 and 77. The vast majority of participants—97%—were female.
Alopecia, a medical term for hair loss, along with natural age-related hair shedding, were the most studied aspects of hair health. Vitamin D emerged as the most frequently examined nutrient or food item of the ones included in the studies:
- Iron
- Protein
- Soy
- Cruciferous vegetables
- Alcohol
- Sweet beverages
- Supplements
The researchers found a link between hair loss and a higher intake of alcohol and sugary drinks. Diets rich in vitamin D and iron appeared to help combat alopecia and hair loss.
There are plenty of good reasons to cut back on sweet drinks and alcohol—but before you nix them over hair loss fears, it’s helpful to know that the study has some major caveats.
While this type of research can show associations between diet and hair loss, it can’t prove causation, Zhaoping Li, MD, PhD, chief of the Division of Clinical Nutrition at the UCLA David Geffen School of Medicine, told Health.
Most of the included studies were cross-sectional, meaning information was gathered at a single point in time, which the authors noted made it “impossible” to carry out a comprehensive meta-analysis. The study designs and analyses varied widely, making it hard to draw firm conclusions, Li added.
Plus, because most of the participants were women, it’s unclear whether the findings apply more broadly.
The role that alcohol and sugary drink consumption truly plays in hair health is still fuzzy. But experts said these habits could theoretically contribute to hair loss for one simple reason: they may interfere with your body’s ability to absorb the nutrients that support healthy hair.
“One probable cause for the link between hair loss and sugary drink and alcohol intake could be the role these beverages play on the gut microbiome, nutrient absorption and that those who consume these beverages may be consuming less food,” Zumpano said.
That could mean less vitamin D, for instance, which Zimpano explained “is essential for creating the cells that develop into hair follicles.” Another key nutrient, as the study suggests, is iron, which helps deliver oxygen to hair follicles.
You might also miss out on other nutrients and foods not specifically linked with hair growth in the study, but that Zimpano said can support hair strength, such as vitamin C, soy products, and cruciferous vegetables like Brussels sprouts and broccoli—which offer fiber, protein, vitamin A, vitamin C, and folate.
“If a person’s diet is deficient in the essential vitamins for hair growth, we know that is a very important factor,” Zimpano explained.
Or, as Li put it: “Nutrition is the foundation of hair health.”
