Low biotin intake linked to 14–16% higher risk of anxiety, depression diagnosis

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Biotin is best known as a staple of hair and nail supplements — a fixture on the ingredient lists of products marketed for hair loss. Also called vitamin B7, it is an essential nutrient that helps enzymes break down fats, glucose and amino acids in the body.

A deficiency, however, does more than thin hair. The National Institutes of Health's Office of Dietary Supplements says adults with biotin deficiency can develop neurological symptoms including depression, lethargy, hallucinations and numbness in the limbs.

Whether the amount of biotin consumed through everyday meals — short of outright deficiency — is connected to mental health had been less clear. A 2021 study of 7,387 adults in Iran found that higher biotin intake was associated with fewer symptoms of depression, anxiety and stress.

That study, however, captured only a single point in time, making it impossible to determine whether low biotin intake led to poorer mental health or whether people already struggling mentally were simply eating less and therefore getting less biotin.

More recent research suggests that people with the lowest dietary biotin intake face a higher risk of being diagnosed with anxiety or depression later in life — though the benefit appears to plateau beyond a certain intake level.

A research team at the School of Public Health at Qingdao University in China published findings in the international journal Frontiers in Nutrition on Jan. 2, tracking 144,439 British adults over 14 years. The study found that the three groups with higher biotin intake had a 14 to 16 percent lower risk of being diagnosed with anxiety or depression compared with the group that consumed the least.

Less biotin, greater anxiety and depression risk

The research team analyzed 144,439 participants from the UK Biobank — a large British health database — who had no anxiety or depression at the start of the study.

Participants recorded everything they ate over the course of a day up to four times between 2006 and 2010, and the team calculated daily biotin intake using nutritional data tables. Biotin taken through supplements was excluded from the calculations.

Participants were divided into four groups based on intake level. The lowest-intake group consumed 32 micrograms or less per day. By the time follow-up ended in September 2023, 12,023 participants had received a diagnosis of anxiety or depression.

Compared with the lowest-intake group, the other three groups were 14 to 16 percent less likely to be diagnosed with anxiety or depression. The risk difference held after the team adjusted for age, sex, smoking, alcohol consumption, daily caloric intake, education level, diet quality and pre-existing conditions.

In terms of case rates, the lowest-intake group was diagnosed with anxiety or depression at a rate of 7.3 per 1,000 people per year. The rate in the other three groups ranged from 5.6 to 5.9 per 1,000 people per year.

The risk of anxiety or depression fell as biotin intake increased, reaching its lowest point at around 45 micrograms per day. Beyond that threshold, however, higher intake did not reduce the risk further. The research team noted that this level is slightly above the 40-microgram daily intake recommended for adults by the European Food Safety Authority.

The team added that lifestyle factors such as physical activity, sleep and stress may also influence inflammation and mental health.

Supplement clinical trials show no clear improvement in anxiety or depression

The study looked only at biotin obtained through food. Whether taking biotin supplements reduces anxiety or depression remains an open question that this research does not address.

A research team at Swinburne University in Australia published a 2019 meta-analysis of 16 clinical trials involving 2,015 participants who took supplements combining three or more B vitamins for more than four weeks. The analysis found that B vitamin supplements modestly reduced stress compared with a placebo, but produced no significant improvement in depression or anxiety.

The Qingdao University team acknowledged limitations: dietary records relied on participants' memory and may contain errors, and the study population was predominantly white, making it difficult to generalize the findings to other groups.

The team nonetheless said that getting an adequate amount of biotin through food may help lower the risk of anxiety and depression, and called for follow-up research examining lifestyle factors, medication use and multiple nutrients together.

Meanwhile, the NIH's Office of Dietary Supplements says most people get enough biotin through diet alone. Biotin is found naturally in foods such as eggs and salmon.

dbsdn1110@heraldcorp.com