For many people, maintaining healthy hair goes beyond a good hair cut or buying the latest products. According to new research, hair health begins with a nutritious diet.
Reviewing the effects of diet and nutrition on hair loss
For the review, researchers followed PRISMA guidelines, considered the gold standard for systematic reviews, and registered their work on PROSPERO.
They scoured three big scientific databases — PubMed, Web of Science, and Scopus — looking for studies published between March and June 2024.
Using keywords like “dietary intake,” “nutritional status,” “hair growth,” and “hair loss,” they started with 1,287 articles.
After filtering for English and Portuguese studies and removing duplicates, 880 remained.
Two reviewers independently checked which studies fit their criteria: participants had to be 3 years or older, studies had to focus on specific nutrients or foods, and hair outcomes had to include things like growth, texture, or strength. Non-human studies, reviews, and case reports were left out.
Eventually, 17 studies made the cut. They included more than 61,000 participants — mostly females ages 7 to 77 — and spanned different study types like randomized trials, case-control studies, and cohort studies.
The researchers also assessed the quality of each study, finding some variability, but overall the results offered a clear picture of what we currently know.
The review further highlighted that alopecia was the most frequently studied hair condition, with eight studies focusing on its severity and occurrence, and five studies assessing hair loss more generally.
Various assessment methods were used, ranging from clinical history and physical examination to objective measures like the Severity of Alopecia Score (SALT) and phototrichograms, ensuring a broad evaluation of hair health outcomes.
Vitamin D, other nutrients promote hair health
Among the nutrients studied, vitamin D emerged as the most extensively researched, with five studies focusing on its relationship to hair conditions such as alopecia areata (AA) and androgenetic alopecia (AGA).
Most of these studies found an inverse correlation between vitamin D levels and the severity or duration of alopecia, suggesting that higher vitamin D status may be protective against these hair loss disorders.
However, one study did not find any association, highlighting the need for further clarification.
Iron was another nutrient highlighted for its positive impact on hair health.
One study showed that iron supplementation (100-milligram tablets) improved hair growth among women with alopecia, supporting the role of iron in hair follicle metabolism and cellular proliferation.
Conversely, protein deficiency was found to negatively affect hair health by reducing hair bulb diameter and pigmentation, emphasizing the importance of adequate protein intake for keratinproduction, the key structural protein in hair.
Foods, drinks, and supplements that affect hair health
The review also examined the role of specific foods and beverages as well as certain supplements commonly used for preventing hair loss and encouraging better hair growth.
Consumption of soy products and cruciferous vegetables was associated with reduced hair loss, possibly due to their antioxidant and anti-inflammatory phytochemicals such as isoflavones and carotenoids.
On the other hand, higher intake of alcoholic and sugary beverages was linked to increased hair loss and premature hair depigmentation.
These findings suggest that certain dietary choices can exacerbate or mitigate hair health issues.
In addition to individual nutrients and foods, several studies investigated the effects of dietary supplements containing combinations of vitamins, minerals, and plant extracts.
Supplements such as INVERSION Femme (which includes green tea and grape extracts, beta-carotene, zinc, selenium, and various vitamins) and marine protein formulations showed promising results in reducing hair loss and promoting hair growth.
Similarly, oral supplementation with hydrolyzed eggshell membrane and persimmon leaf extract was associated with improvements in hair density and thickness.
