The review included 17 English- and Portuguese-language studies focused on diet and hair, and included more than 61,000 participants, almost all of them female.
Here’s what the evidence revealed:
- Sugary drinks in excess of 3,500 milliliters (ml) per week (about 10 12-ounce cans) were connected with hair loss, particularly in men.
- Alcohol was linked to an increase in hair loss.
- Vitamin D deficiency was connected to hair loss severity in alopecia areata (an autoimmune disease) and androgenetic alopecia (male or female pattern baldness).
- Iron supplementation was linked to improved hair growth, particularly in women.
- Protein, soy products, and cruciferous vegetables (think kale and broccoli) were tied to improvements in hair growth and hair density.
What Is Hair Loss, and How Is It Linked to Diet?
“We know that nutrition is intimately tied to hair biology,” says Adam Friedman, MD, a professor and the chair of dermatology at George Washington University School of Medicine and Health Sciences in Washington, DC.
Sugary foods and drinks are known to exacerbate inflammatory scalp conditions, he says, which in turn can cause or worsen hair loss. On the other hand, “Vitamin D and iron have been consistently implicated in maintaining healthy follicular function,” Dr. Friedman notes, referring to hair follicles, the skin openings from which hair grows.
According to Friedman, the review results support what experts already know about diet and hair loss — but it shouldn’t spur anyone to make abrupt dietary changes and expect immediate hair health results.
“The findings align with clinical intuition: A balanced diet supports healthy hair, while dietary excesses or deficiencies can tip the balance towards loss,” he says.
He adds, “Cutting back on alcohol and sugary drinks may reduce further alopecia and create a more favorable scalp environment for growth, but there’s no strong evidence that it will reverse established hair loss or regrow hair once follicles have miniaturized or the scalp has scarred.”
In other words, making healthier choices may help prevent hair loss but not treat it.
But “ultimately, the message to patients is empowering: What you eat and drink influences your hair, and small, sustained changes may help preserve what you have,” Friedman says.
What Are Some Limitations of the Research Review?
This review has a number of limitations, including the inclusion of research beyond randomized controlled studies (considered the gold standard), the majority female participant pool, and self-reported dietary habits, says Susan Massick, MD, an associate clinical professor of dermatology at the Ohio State University Wexner Medical Center in Columbus who was not involved in the new review.
Dr. Massick warns about the problem of “lumping everything together,” given the many different types of alopecia. “Remember that hair loss can be multifactorial, with a goal of treatment to reverse the reversible, target the cause of the hair loss, and embrace the overriding themes of healthy diet, stress management, and adequate sleep as the mainstays of any health regimen,” she says.
“Not all alopecias are the same, with a wide range of causes, triggers, physical exam features, and thus different treatments, prognoses, and outcomes.”
The scientists behind the new research review noted that further studies are needed to deepen the understanding of the association between nutrition and hair loss before any evidence-based recommendations on diet and supplementation can be made.
When to See a Doctor About Hair Loss
Deborah A. Scott, MD, a codirector of the hair loss clinic at Brigham and Women’s Hospital and an associate professor of dermatology at Harvard Medical School in Boston, says that these medical professionals can test for any suspected vitamin deficiencies as part of a hair loss treatment plan.
“I would just make sure that your vitamin D levels are in the normal range. And particularly if you’re a vegetarian, make sure that you’re getting adequate iron.”
