By Heidi Splete, Contributing Writer, July 1, 2023

Nutritional supplements appeal to many individuals as an alternative or additive treatment for skin and hair ailments, but evidence to support the effectiveness of many of these products remains inconsistent.

DermWorld reviews three common products — biotin, collagen supplements, and probiotics — that many of your patients may be using, with or without your knowledge, and offers expert comments on pros, cons, and cautions.

Biotin: There’s no hair there

Data from a recent study in JAMA suggest that the use of biotin has increased in recent years, especially among women and older adults (doi:10.1001/jama.2020.8144).

“Over-the-counter biotin supplements, especially in high dosages (≥5 milligrams/d, or 166-fold greater than the dietary recommendation of 30 micrograms/d), are widely available and marketed as having health benefits such as stimulating growth of hair and nails,” wrote Danni Li, PhD, of the University of Minnesota, Minneapolis, and colleagues. The researchers reviewed data from the National Health and Nutrition Examination Survey (NHANES) to identify trends in self-reported biotin use of at least 1 mg/day and 5 mgs/day.

The overall use of at least 1 mg/day of biotin increased from 0.1% in 1999-2000 to 2.8% in 2015-2016. Use of at least 5 mgs/day of biotin was not reported prior to 2007-2008, but use of the higher amount also increased over time, from 0.1% in 2007-2008 to 0.7% in 2015-2016 (P < 0.001 for both doses). Increases were especially high in older women, with prevalences of 7.4% and 2.3% for 1 mg/day and 5 mgs/day, respectively.

However, biotin deficiency is rare, and research shows little benefit of biotin supplementation for most people who use it. No clinical trials currently exist to support claims that biotin supplements improve hair or nail growth or quality.

In fact, excess biotin can skew results of certain lab tests, notably those for troponin, a biomarker used to diagnose heart attacks, according to a 2022 safety communication from the FDA. The communication alerted the public and physicians about the potential for biotin interference in lab tests and includes a list of In Vitro Diagnostic Devices that might be impacted by interference from excess biotin.

“I have a saying, ‘nutritional supplements, despite the name, are not the same as nutrition,’” said Rajani Katta, MD, FAAD, a dermatologist in Houston, and the author of a book for the public on diet and dermatology. “We have to approach supplements the same way we approach any medication and review the risks versus the benefits in detail; this takes time spent learning about each supplement and time spent explaining it to the patient,” she said.

When reviewing supplements for potential recommendations to patients, Dr. Katta starts with PPIES (purity, potency, interactions, efficacy, and safety). “You need to know about the purity and potency of the original product, the potential interactions, efficacy, and safety of all of the ingredients,” she said.

Educating patients on the risks of supplements is a major challenge because the risks are not studied in any systemic way, and adverse effects may not appear until years later, Dr. Katta said. “Ingredients in supplements advertised for skin, hair, and nail use have been linked to birth defects, interference with lab tests, an increase in cancer risk, and even side effects such as acne and hair loss,” she said.

Despite potential risks, some individuals may benefit from certain supplements for dermatologic conditions, Dr. Katta said. “I’m really intrigued by research showing that for adults with atopic dermatitis, probiotics may be helpful in a subset, but we really need more data about type, dose, and duration of probiotic therapy, as well as how to identify patients who may benefit,” she said.

Other intriguing research includes nicotinamide for skin cancer prevention in high-risk patients, and zinc for acne, she added.

Overall, “When it comes to supplements, I believe that some are powerful, some are placebos, but all must be handled with care,” Dr. Katta emphasized. “In the right setting, for the right patient, the potential benefits may outweigh the risks,” she said. Use of supplements to correct a nutritional deficiency is a different situation than supplement use strictly for a dermatologic condition, she added.

“The bottom line is that it really depends on the particular supplement, which is why choosing the exact right formulation for the right condition, and discussing the risks, is so important,” Dr. Katta said. As for patient guidance, the unfortunate fact remains that there is no premarket approval process for supplements, so it is easy to bring a product to the market, she said. The FDA has limited resources to monitor these products, which is why patients must be careful, she emphasized.

“At a bare minimum, advise patients to only purchase supplements that contain verification by a third-party investigative laboratory ensuring that a product is not contaminated, and that its advertised dose is accurate,” Dr. Katta told DermWorld. “Both areas have been big issues over the years, so that seal of approval by labs such as ConsumerLab or USP is important,” she said. “Beyond that, even if we’re not sure about efficacy, it’s important to talk about safety of the ingredients. Megadoses of vitamins and minerals are concerning to me,” Dr. Katta said.

As for additional research, “With tens of thousands of supplements on the market, we need significantly more research on efficacy and safety,” Dr. Katta said. “For efficacy, I would particularly point to gaps in our knowledge when it comes to patient selection, optimal dosage, and optimal duration. For safety, more long-term studies are needed.”

Dr. Katta cited one trial of multi-ingredient vitamin and mineral supplementation for skin cancer prevention that contained high doses of five antioxidants, including vitamins C, E, and selenium. “Unfortunately, after 7.5 years, women taking the supplement had higher rates of skin cancer. Experts now believe that antioxidants at high doses can become pro-oxidant, but that result was only apparent because this supplement was studied rigorously,” she noted.

Autoimmunity issues

Some supplements are available to consumers that stimulate the immune system, especially in those with autoimmune disease, said Victoria P. Werth, MD, FAAD, professor of dermatology at the University of Pennsylvania. “There are laboratory studies that demonstrate the effect of some supplements on activating inflammatory cells, which then produce proteins that further stimulate the immune system.” Therefore, “we advise patients to check with their doctor before starting a new supplement,” she said.

“There is increased use of herbal supplements in patients with autoimmune skin diseases, especially in dermatomyositis,” said Dr. Werth. “Some patients experience flares or even new onset of disease in the setting of stating use of these herbs,” she said. In particular, herbs including spirulina, green algae, chlorella, ashwagandha, and elderberry have demonstrated stimulatory effects, which can cause problems for those with personal or family histories of autoimmune disease, she added.

There is insufficient evidence for the safety of supplements, including probiotics, with regard to autoimmune conditions, said Dr. Werth. “We don’t have enough data about the safety of probiotics, but if a supplement is thought to protect against viruses and other infections, there is a chance that may aggravate autoimmunity.”

Given the popularity of supplement use, Dr. Werth recommends that physicians keep a list of immunostimulatory herbs and the products that contain them. “Many patients think of these supplements as healthy and will not immediately think they are a problem. Dermatologists should ask about herbs and look up the ingredients to determine safety,” she said. “Even some green juices and smoothies contain spirulina, and these should be avoided in patients with autoimmune issues.” Although exposures to supplements are frequent, more research is needed to better understand the risk in those with personal or family histories of autoimmunity, Dr. Werth added.

Collagen concerns

Collagen is available to consumers in both oral and topical formulas, and is often marketed as an anti-aging ingredient, although it may also target those seeking to boost skin recovery and repair. Oral collagen in a hydrolyzed form has become popular, but the evidence for efficacy remains mixed. A meta-analysis and systematic review published in the International Journal of Dermatology included 19 studies and a total of 1,125 individuals aged 20 to 70 years. The researchers found reports of improvements in skin hydration, elasticity, and the appearance of wrinkles, which were confirmed in a subgroup analysis. Most of the favorable results involved 90 days of use. A 2019 study published in the Journal of Drugs in Dermatology reviewed data from 11 studies with a total of 805 individuals who consumed oral collagen for conditions including pressure ulcers, xerosis, skin aging, and cellulite (2019. 18(1):9-16). The researchers found no adverse events associated with oral collagen use, although they acknowledged the lack of regulation of ingredients in collagen supplements and the limited peer-reviewed studies.

Probiotic proclivities

The term “probiotics” covers a range of consumer products and supplements, most of which are advertised as aids to digestive health. However, probiotics have also been marketed as ways to improve skin conditions such as atopic dermatitis. These claims are not completely unfounded; a study published in the European Journal of Dermatology in 2021 randomized 80 adults with mild-to-severe atopic dermatitis to placebo food capsule or capsule with a mixture of lactobacilli (doi: 10.1684/ejd.2021.4019). After 56 days, the patients in the probiotic group showed significant improvement in skin smoothness, skin moisturization, self-perception, and decreased scores on the scoring atopic dermatitis (SCORAD) assessment. No differences were noted between the two groups in terms of erythema and edema.

The study was limited by the small sample size, but the data support previous studies of the connection between gut and skin, the researchers wrote. “Treatment focused on gut dysbiosis could help relieve distress related to skin disorders and may be complementary to standard dermatological therapy,” they concluded.

Evidence-based education

When talking to patients about supplement use, the bottom line is that these products do not provide a quick fix, experts agree. When advising patients who ask about nutritional supplements to improve skin and hair health, the two greatest challenges are “a lack of high-quality data supporting decision making and heterogeneity in the formulations of supplements,” said Arash Mostaghimi, MD, FAAD. “Not only do we not know precisely what works and what doesn’t, but the doses and exact compounds patients take vary highly based on the brands they are using,” said Dr. Mostaghimi, assistant professor of dermatology at Brigham & Women’s Hospital in Boston.

Some patients with nutritional deficiencies such as low vitamin D levels may benefit from supplements, Dr. Mostaghimi said, but for most people “sticking with tried-and-true prescription medications is the best way forward.”

The greatest risk associated with supplements is financial, according to Dr. Mostaghimi. “Patients may be paying hundreds of dollars for medications that they do not need,” he said. “Outside of minor side effects, it appears that most supplements are safe, but we have never studied these interventions in the systematic way that would be required to identify rare side effects,” he noted.

When advising patients who want to explore supplements “sticking with known brands sold in major U.S. retail stores is a great place to start,” said Dr. Mostaghimi. “I am wary of medications from overseas or from online sources that either do not say what they have in them or may have ingredients that are not on the label.”

For a more thorough understanding of the risks and benefits of supplements, truly randomized, placebo-controlled trials are needed, Dr. Mostaghimi said. “Without this information, we will continue to be limited in our recommendations,” he said. In a systematic review published in 2022 in JAMA Dermatology, Dr. Mostaghimi and colleagues identified 30 articles related to dietary and nutritional interventions for hair loss, including 17 randomized clinical trials, 11 non-randomized clinical trials, and two case series. The findings must be interpreted in the context of each study, the researchers noted, but they found that adverse effects were mild and rare for all the supplements studied (see sidebar).

The current state of evidence showing benefits of nutritional supplements for hair loss is very limited, Dr. Mostaghimi said. “We do not have enough data to actively recommend any specific supplements, but dermatologists should be acquainted with the existing data to help inform patients who are committed to their use.” When patients ask about supplements, clinicians should be honest about the limitations, Dr. Mostaghimi said. “We have lots of prescription medications that we know work,” and patients who are committed to medication use should stick to products supported by more clinical data, he added.