Benefits and risks of hair, skin, and nail supplements in older adults

Abstract

Many older adults, particularly older women, use over-the-counter supplements for antiaging benefits, including for hair and skin. The supplement industry is unregulated by the Food and Drug Administration, and the interactions between supplements and medications are often overlooked by both patients and physicians. This article discusses the proposed mechanism of action, common misconceptions, possible benefits, and potential side effects of the most commonly used antiaging skin supplements by women, including biotin, nicotinamide, hyaluronic acid, collagen, zinc, vitamin C, vitamin A, vitamin E, and other antioxidants. Supplements may also interfere with common blood tests, such as biotin with the thyroid and troponin cardiac enzyme tests, which patients and their clinicians must be aware of and account for when interpreting lab results. Other supplements, such as zinc, are commonly taken in excess and may result in deficiencies in the absorption of other minerals, such as copper. Over-supplementation of fat-soluble vitamins, such as vitamin A and vitamin E, can result in toxic levels since excess is not excreted in the urine. The clinician caring for older patients’ skin and nails must ask older patients about supplement use and be aware of the potential harms of these supplements in some patients.

What is known about this subject in regard to women and their families?

• It is known that the cosmetic supplement industry is widely unregulated, filled with misinformation, and has the potential to harm patients.

• These supplements are often marketed towards women as an antiaging solution, and women aged 60 and older report the highest usage of dietary supplements.

What is new from this article as messages for women and their families?

• This article reviews the potential benefits and risks associated with the most common hair, skin, and nail supplements used by older patients.

• It offers guidance for physicians to provide patients with evidence-based information to guide their supplement use and minimize potential harms.

• It discusses the role of polypharmacy in supplement use among older patients who are at risk for drug-supplement interactions.

Introduction

Patients often seek advice for skin changes caused by years of sun exposure, nutrient deficiencies, genetics, and other factors. Nearly 80% of geriatric patients have at least 1 skin disease, and over one-third of geriatric patients have 3 or more skin diseases at once.¹ Some common skin concerns among older patients include wrinkles, hyperpigmentation, skin cancers, venous stasis changes, and impaired wound healing. In attempts to improve these conditions, many patients take dietary supplements for hair, skin, and nail health. This branch of the supplement industry has nearly doubled from 2011 to 2020 and continues to grow.²

An analysis of over three thousand Americans 60 years or older from the 2011 to 2014 National Health and Nutrition Examination Survey showed that 70% of respondents reported using a dietary supplement within the last 30 days. Women were nearly twice as likely to report supplement use as men, and 29% of the respondents used 4 or more supplements.³ Supplement use is also reportedly the highest among women aged 60 and over (80.2%).⁴

The cosmetic dietary supplement industry has a large and rapidly growing market, and a significant proportion of these products claim to “promote healthy hair, skin, and nails.” However, the purported claims of dietary supplements are generally not regulated by the US Food and Drug Administration (FDA), and there are often inconsistent and confusing dosing instructions, outdated daily nutritional value reference labels, and a lack of independent laboratory quality testing.⁵ There are governmental efforts to improve regulation, such as the Botanical Safety Consortium and the National Center for Natural Products Research, but the FDA has limited ability to review supplements before they are available in the market.⁶ Patients who take 3 or more prescription medications are more likely to report supplement use, raising concerns related to polypharmacy, drug-drug interactions, laboratory testing interference, and other adverse events.³ Therefore, patients should be carefully counseled on the use of dietary supplements for their purported antiaging benefits.

The aim of this narrative review is to evaluate the evidence for several of the most common supplements for hair, skin, and nails, as well as potential concerns.

Methods

A literature search was conducted on PubMed to identify common supplements discussed in the literature used for hair, skin, or nails. Key words or phrases included: “supplement,” “geriatric,” “older adult,” “elderly,” “senior,” “aged,” “hair,” “skin,” “nails,” “efficacy,” and “effect.” Based on this initial review, the most commonly used and cited supplements were included in this narrative review: biotin, nicotinamide, hyaluronic acid, collagen, zinc, vitamin C, vitamin A, and vitamin E. A total of 64 articles were included.

Discussion: commonly used supplements

Table 1 summarizes the use, efficacy, maximum doses, and key considerations for supplements commonly used for hair, skin, and nail health. Detailed discussion of each of these supplements is as follows.

Table 1.

Summary of common supplements used for hair, skin, and nails

Supplement	Purported use	Does it work?	Maximum or recommended safe dosages	Concerns and considerations
Biotin	Improves the appearance of skin, hair, and nails	May improve skin and hair findings if they are primarily caused by biotin deficiency (rare)	Toxicity is uncommon, even in very high doses	May interfere with laboratory results, including TSH and troponin levels
Zinc	Improves wound healing	May improve skin and hair findings if they are primarily caused by zinc deficiency	40 mg daily (FDA guidelines)	GI Toxicity at high levels. May result in copper deficiency. Excess zinc may also interfere with the efficacy of medications such as antibiotics
DHEA	Increases skin hydration and thickness	Limited data to ascertain if the benefits outweigh the risks	25 to 50 mg/d in older participants7	Increase in testosterone may cause hirsutism and acne. Theoretical increased risk of hormone-sensitive cancers
Pre- and Pro-biotics	Increase the diversity of the skin microbiome	May increase skin barrier protection	Varies with the type of prebiotic/probiotic	Limited data about risks
Nicotinamide	In vitro studies show restoration of age-related mitochondria function decline	Can decrease the prevalence of actinic keratoses in higher-risk populations	3,000 mg/d	Limited clinical trials Hepatotoxicity at high doses
Hyaluronic acid	Reduces the appearance of wrinkles	Can improve skin appearance due to increased water retention	200 mg/d in clinical trials	Limited clinical trials Industry-funded studies
Collagen	Improves the appearance of skin, hair, and nails	Can improve skin density and hydration, brittle nails	Varies with formulation	Limited clinical trials Industry-funded studies
Antioxidant: Vitamin C	Collagen synthesis, photoprotection	Specialized, stabilized serum formulas of Vitamin C may help with skin hydration	2,000 mg/d	Deficiency causes scurvy Toxicity causes GI side effects
Antioxidant: Vitamin E	Photoprotection	May help with reducing UV-induced damage	1,000 mg/d	High doses increase risk of death, bleeding risk, and drug-drug interactions
Antioxidant: Vitamin A and carotenoids	Increases skin turnover	Diminishes the appearance of wrinkles and acne scars	3,000 mcg/d	Deficiency may cause follicular hyperkeratosis. Excess may cause GI effects, liver problems, hair loss, and birth defects

DHEA, dehydroepiandrosterone; GI, gastrointestinal; TSH, thyroid stimulating hormone; UV, ultraviolet.

Biotin

Biotin, vitamin H or B7, is a common hair, skin, and nail supplement. Biotin is a coenzyme involved in carboxylation, gluconeogenesis, lipogenesis, fatty acid synthesis, and other reactions that serve to build proteins, promote brain function, regulate metabolism, and boost immunity.⁸

Biotin can be naturally found in foods such as egg yolk, liver, cereals, vegetables, and rice.⁹ Biotin is also created as a byproduct by bacteria in the gut microbiome.¹⁰ For adults, the Food and Nutrition Board of the Institute of Medicine recommends a dietary intake of 30 mcg/d.⁹

Biotin deficiency is very rare in healthy patients who eat a balanced diet. Patients may become deficient in biotin when consuming too many egg whites, receiving parenteral nutrition without biotin supplementation, or taking medications such as antiepileptics, oral antibiotics, or isotretinoin.⁹ Biotin deficiency is also more common in individuals with chronic alcohol consumption.¹¹ A deficiency of biotin presents as hair thinning, brittle nails, and scaly facial rash.⁹ Biotin toxicity is rare as it is a water-soluble vitamin that can be excreted via the urine.¹²

Evidence

There is some evidence to suggest that biotin supplementation may be beneficial in individuals who have alopecia as a side effect of valproic acid therapy, with case reports and studies suggesting 10 mg/d may be helpful.^13,14 In a clinical trial of 75 pediatric patients with seizures treated with valproic acid, a dose-dependent decrease in biotinidase was noted, and of the 29 patients with dermatologic side effects, 12 had resolution of symptoms with biotin supplementation.¹³ A separate study comparing pediatric patients treated with valproic acid, carbamazepine, and healthy controls did not find significant differences in biotinidase activity, but for all 3 patients out of 57 who had alopecia, supplementation with biotin of 10 mg/d resolved hair loss at 3 months.

In healthy individuals with no underlying deficiencies, there appears to be very limited evidence that biotin has a positive impact on hair, skin, and nails. Most of the evidence appears to be limited to case reports in patients with underlying pathology causing hair loss, such as congenital biotin deficiency, brittle nail syndrome, or uncombable hair syndrome.¹⁵ A more recent randomized controlled trial of 10 healthy male participants did find that the concomitant use of topical minoxidil and oral biotin daily for 14 days increased the speed of hair growth and percentage of skin covered by hair compared to the use of biotin or minoxidil alone.¹⁶ However, this study is limited in duration, number of participants, lack of formal measurements of hair density, and the exclusion of female patients.

Concerns

Biotin supplementation can interfere with laboratory findings such as thyroid hormone levels, troponin levels, β-subunit of hCG gonadotropin (β-HCG) testing, HIV serologies, vitamin D levels, and other Western Blot assays that use biotin technology.^17–19 The FDA issued a warning that biotin can result in elevated or diminished troponin levels and interfere with the diagnosis of heart attacks.²⁰ It is recommended that patients abstain from taking biotin at least 48 hours before laboratory tests to prevent interference.²¹

A study analyzing consumer perceptions of biotin demonstrated that “biotin supplementation is prevalent and perceived as helpful despite limited evidence of improvement.”²² Biotin deficiency is rare, making supplementation unnecessary. Although biotin does not commonly have side effects or toxicities, most biotin users are unaware of how biotin can interfere with their laboratory results and potentially impact the care they receive, including unnecessary follow-up testing, or more concerning, interference with serious diagnoses such as a myocardial infarction.²²

Nicotinamide

Nicotinamide, also known as niacinamide, is a form of vitamin B3 and a nicotinamide adenine dinucleotide (NAD+) precursor. The use of nicotinamide for antiaging has been an increasing area of interest. It is often discussed alongside its analogs, nicotinamide riboside, nicotinamide mononucleotide, and niacin (also known as nicotinic acid), which are also NAD+ precursors. NAD+ is important in intracellular redox reactions; however, levels decrease with age and lead to decreased cellular metabolic function. Nicotinamide and its analogs are metabolized in the body into NAD+, thus replenishing decreased NAD+ levels.²³

Evidence

In vitro studies have supported the therapeutic potential of this mechanism to reduce signs of skin aging. Treatment of keratinocytes with nicotinamide was found to inhibit reactive oxygen species (ROS) generation.²⁴ Additionally, treating dermal fibroblasts from donors aged 60 and older restored age-related decreases in mitochondrial function and oxidative phosphorylation.²⁵

Oral nicotinamide was observed to be effective in reducing transepidermal water loss, an indicator of epithelial barrier function.²⁶ Additionally, nicotinamide has been studied regarding the prevention of skin cancer in individuals with sun-damaged skin, which is particularly relevant in patients who experience cumulative sun damage. The administration of 500 mg of nicotinamide daily decreased actinic keratoses in immunocompetent patients.²⁷ Similarly, a twice-daily 500 mg dose in a different clinical trial of participants with a history of skin cancer showed a reduction in both the prevalence of actinic keratoses and incidence of nonmelanoma skin cancers.²⁸ On the other hand, a systematic review found that oral nicotinamide did not play a significant role in preventing nonmelanoma skin cancers; however, it included studies on both immunocompetent and immunocompromised patients.²⁹ Nicotinamide is also often used topically and is a popular ingredient in the cosmetic industry to improve skin tone and signs of aging. A topical application has been shown to be effective in reducing the appearance of wrinkles.³⁰

Concerns

There are limited clinical trials that support the role of oral nicotinamide in reducing the appearance of aging, as research has been limited to animal and in vitro studies. Additionally, while nicotinamide is generally safe and well-tolerated, hepatotoxicity has been reported when taken above 3,000 mg/d. Diarrhea has also been reported at doses of 1,000 mg/d or more, resolving with dose reduction. For patients with end-stage renal disease, nicotinamide can lead to thrombocytopenia, which will resolve with discontinuing the supplement.³¹

While there is promising data regarding nicotinamide’s efficacy in skin health for the older population, more research is required.

Hyaluronic acid and collagen

In the body, both hyaluronic acid (hyaluronan, HA) and collagen are essential components of the extracellular matrix. During the aging process, their abundance in the skin decreases, which can lead to the loss of skin integrity. Both are popular ingredients in cosmetic products, often sold as topical formulations. There is some evidence that these topical products can reduce signs of aging by keeping the skin moisturized.^32,33 However, the size of the collagen peptide may not allow it to penetrate properly into the skin.³⁴ Oral supplementation of HA and collagen is of interest due to the potential for more systemic benefits compared to topical application.

Evidence

HA is a glycosaminoglycan, so the use of HA is thought to have antiaging effects due to its ability to retain water in the skin, which can reduce the appearance of wrinkles. Clinical studies have supported its efficacy in decreasing transepidermal water loss, improving levels of skin moisture, and decreasing wrinkle depth and volume.^35–37

Collagen supplements are widely available in pharmacies and are increasingly popular for hair, skin, and nails. Supplementation has been shown to induce collagen synthesis, reduce collagen fragmentation, and increase glycosaminoglycan synthesis in the skin.³⁸ Changes in the skin have also been observed through the improvement of the appearance of wrinkles, as well as skin density, elasticity, and hydration.^33,39 Additionally, collagen use can potentially improve brittle nails.⁴⁰ There is a wide range in dose recommendations due to the different types of collagen formulations used in studies—intact or hydrolyzed.⁴¹ No adverse events in these studies have been reported.

Concerns

Clinical trials supporting the use of collagen and hyaluronic acid remain limited, so it is difficult to generalize its efficacy across patients. Additionally, a significant proportion of the literature that was found on both collagen and HA is funded by cosmetic industries, raising concerns about potential conflicts of interest in these clinical studies.^36,37,39 Additional evidence from independent studies is required to draw additional conclusions about collagen and HA supplementation.

Zinc

Zinc is a trace metal found naturally in the human body that helps with wound healing, immune system function, and metabolism. It is primarily absorbed by the small intestine, and its absorption can be decreased by iron, fiber, and alcohol intake, as well as chronic diarrhea or inflammatory bowel diseases.⁴² Zinc deficiency has also been reported due to increased urinary loss of zinc caused by diuretic medications.⁴³ Zinc deficiency is rare but can present as a dermatitis with erythematous, scaly, and dry patches located on the face, anogenital area, and extensor surfaces, which can resemble psoriasis. Additionally, zinc deficiency can cause hair loss, poor wound healing, and immune deficiency.

The recommended daily dietary intake for adults is 11 mg for men and 8 mg for women.⁴⁴ About 45% of American adults have an inadequate zinc intake, and those aged 60 years and older can have zinc intakes of less than half of the recommended daily allowance.⁴⁵

Evidence

There is limited evidence to support the efficacy of zinc supplementation in healthy individuals without zinc deficiency. However, in limited case studies, zinc supplementation has been shown to increase the duration of botulinum toxin effects when used for medical and cosmetic treatments.⁴⁶

Concerns

Over-supplementation is common and can be harmful, as the FDA recommends 40 mg per day as the tolerable upper intake level. Zinc toxicity consists of general gastrointestinal symptoms and possible renal toxicity in rare cases.⁴⁷ Elevated levels of zinc can result in a copper deficiency.⁴⁸ Zinc supplementation can also decrease the efficacy of antibiotics and penicillamine used to treat rheumatoid arthritis.^49,50

Inadequate zinc intake can occur among geriatric patients, but routine supplementation is not required for nondeficient patients and may result in adverse effects.

Dehydroepiandrosterone

Dehydroepiandrosterone (DHEA) is an androgen-like product of the human adrenal gland and is responsible for producing testosterone and estrogen. DHEA naturally decreases with age—in premenopausal women, DHEA levels can range between 1.12 and 7.43 ng/mL, decreasing to 0.6 to 5.7 ng/mL after menopause.⁵¹ Patients with DHEA deficiency can present with weakness, skin dryness or atrophy, low bone density, dyspareunia, genitourinary syndrome of menopause, and mood imbalances.

Evidence

Oral supplementation with 5 mg/d has been shown to increase skin hydration, thickness, and pigmentation, as well as improve libido with no reported adverse effects, although further studies with oral supplementation have been limited.⁵² Topical DHEA application has also been shown to stimulate collagen synthesis in the skin of postmenopausal, suggesting an antiaging effect and is available as prasterone, a prescribed intravaginal topical medication for the treatment of dyspareunia caused by vulvar or vaginal atrophy.⁵³

Concerns

DHEA supplementation can have female-specific effects due to the increase in testosterone, such as hirsutism and acne.⁵⁴ Because the body uses DHEA to make estrogen and testosterone, it can cause a theoretical increase in the risk of hormone-sensitive cancers such as breast and ovarian cancers.^55,56 Data is limited to the benefits of DHEA, but potential risks may outweigh the benefits for most individuals when taken for just skin concerns.

Prebiotics and probiotics

The skin’s microbiome plays an essential role in protecting against pathogens and activating both innate and adaptive immune responses.⁵⁷ The microbiome diversity tends to decrease with age, and limited data show it possibly plays a role in skin aging and declining skin health.⁵⁸ Products that strengthen the microbiome may contain prebiotics, which are nutrients that promote microorganism growth, and probiotics, which are live microorganisms that are introduced directly into the microbiome.⁵⁸

Evidence

Limited studies have found that specific probiotics may regulate the skin’s pH, prevent UV-induced photodamage, and improve skin barrier protection.⁵⁷ Randomized controlled trials of limited prebiotics, such as galactooligosaccharide, and probiotics, including Lactobacillus johnsonii, showed benefits such as reduction in transepidermal water loss and early UV-induced photodamage.⁵⁹ Products emerging in this space also include probiotics within topical skin care products to create healthier skin microbiomes for antiaging effects.⁶⁰

Concerns

Currently, there are limited data and interventional studies regarding the benefits and side effects caused by oral and topical prebiotic and probiotic supplementation for skin care in geriatric patients.

Antioxidants

Many antioxidants have been studied for skin health, including vitamin C, vitamin E, coenzyme Q10, flavonoids, polyphenols, vitamin A, and carotenoids (beta-carotene, lycopene, and lutein). Vitamins C, E, and A are the most commonly used supplements.

Common mechanism of action for antioxidants

Both photoaging from UV light and chronological aging have been shown to activate the same oxidative stress pathways. Skin exposed to UV light generates ROS that can accumulate and contribute to photoaging. The age-related reduction in antioxidant mechanisms in aging skin also contributes to more ROS being present. This activates pathways that cause degradation of collagen, damage to elastin fibers, and depolymerization of hyaluronic acid, resulting in wrinkles, loss of laxity, and skin dryness.⁶¹ As antioxidants are able to prevent and also repair the damage caused by free radicals and reduce oxidative stress, there is great interest in whether topical or oral supplementation of antioxidants would help prevent these changes.

Antioxidants—vitamin C

Vitamin C (ascorbic acid) helps with the synthesis of ceramides-lipids in the stratum corneum and thus helps with maintaining skin hydration. It is required for collagen synthesis, and the absence of vitamin C in humans results in scurvy. However, if a patient is not deficient, it is not clear that high doses of vitamin C help.

Evidence

Studies have also indicated that vitamin C can be a photoprotectant and reduce inflammation of the skin, and it is typically found in all layers of the skin, especially the epidermis. Oral vitamin C was shown to increase the free radical-scavenging activity of the skin within 2 weeks of supplementation, and topical applications have been seen to improve the appearance of photodamaged skin by clinical examination.^62,63

Concerns

However, increasing vitamin C levels in the skin is challenging. Vitamin C is water-soluble, and even high oral doses do not increase skin levels appreciably. Topical vitamin C is not very stable, losing its antioxidant ability as soon as it is exposed to air. Derivatives are not easily absorbed, and specialized stabilized serum formulas have a very short shelf-life.⁶⁴

Vitamin C is not a benign supplement. High doses of vitamin C can result in gastrointestinal side effects and an increased risk of kidney stones due to increased urinary oxalate and uric acid excretion. Recommended amounts of vitamin C are 90 mg for men and 75 mg for women daily, but most supplements have several times this amount of vitamin C in each dose. The maximum recommended is 2,000 mg daily as a supplement.⁶⁵

Antioxidants—vitamin E

Vitamin E (α-tocopherol being the most active form in humans) is a fat-soluble antioxidant that must come from the diet. The stratum corneum of the skin has very high levels of vitamin E coming from the sebum. It is well-absorbed when applied topically since it is lipid-soluble.

Evidence

Studies of Vitamin E have shown improvement in signs of photoaging and reduction in UV-induced damage, but it is not clear that supplementation helps with patients who are not deficient, and true deficiency is rare.^66,67 Yellow nail syndrome is 1 condition in which vitamin E (in combination with fluconazole) has been shown to be efficacious.⁶⁸

Concerns

High-dose supplementation can lead to increased risk of death, increased bleeding risk (especially hemorrhagic stroke), and drug-drug interactions, including interference with antiplatelet or anticoagulant medications. The recommended daily intake of vitamin E is 15 mg. It is not recommended to take more than 1,000 mg of Vitamin E (1,100 IU of synthetic vitamin E). Care must be taken to review other sources of vitamin E due to polypharmacy, as many older patients take other supplements containing vitamin E, such as Age-Related Eye Disease Study (AREDS) supplements to slow progression or prevent age-related macular degeneration, which typically have 400 IU of vitamin E.

Antioxidants—vitamin A and carotenoids

Vitamin A (retinol) is a fat-soluble vitamin and must also be dosed carefully. Vitamin A deficiency causes follicular hyperkeratosis and changes in epithelial tissues, replacing simple epithelial cells with stratified keratinizing epithelium. However, excess vitamin A causes hair loss through effects on the hair cycle, as vitamin A’s metabolite is retinoic acid, which is toxic in high levels. UV radiation is known to cause a decline in retinoid levels in skin cells and affects both melanocytes and keratinocytes.

Evidence

Retinol (vitamin A) is in many over-the-counter topical skin products, but has not been shown to be very effective as it slowly oxidizes into active retinaldehyde or retinoic acid. It does have some UV-light blocking abilities for shorter wavelength UV light (325 nm). A number of studies show that prescription topical retinoids are effective for treating photoaged skin but can cause irritation and peeling.⁶⁹ Topical retinoic acid is many times more potent and thus is used in dermatology as prescription medication for the treatment of conditions such as acne vulgaris, but its potency can be irritating. Tretinoin (all-trans retinoic acid) has been used at low doses to help with photoaging and fine wrinkles. Retinaldehyde, a precursor to retinoic acid, is less irritating and may help with wrinkling. Third-generation retinoids such as tazarotene are also less irritating.^70,71

Concerns

It is recommended that adults receive 900 mcg of retinol-activity-equivalent vitamin A for men and 700 mcg for women. Vitamin A deficiency is very rare in the United States due to the supplementation of many foods. The maximum dose is 3,000 mcg daily. High-dose Vitamin A can result in gastrointestinal side effects, vertigo, blurry vision, liver problems, and birth defects. In extremely high doses (>100 Recommended Dietary Allowance), increased Cerebrospinal fluid pressure, coma, or death can result.

Conclusion

The marketing of supplements often promises a reversal of skin aging, but the evidence supporting these claims is limited. There is aggressive marketing around supplements, unchecked claims of benefit, and potential harm when patients surmise that just because a supplement is “natural,” it is also safe. Although there are some supplements that may be helpful in prevention, such as nicotinamide and active forms of vitamin A for photoaging, the evidence is weak for most supplements other than in patients who are truly deficient. Moreover, the lack of regulation of the supplement industry poses concerns about the quality of the supplement ingredients. Supplements can even cause harm in their interference with laboratory tests and other medications, and may result in adverse health impacts. It is essential that the clinician is aware of these concerns when counseling patients and should educate patients about the dearth of strong evidence for the use of most supplements for hair, skin, and nails.

Conflicts of interest

None.

Funding

None.

Study approval

Not applicable.

Author contributions

All authors contributed to all phases of this manuscript, including conception/design, analysis/interpretation of data, drafting of the paper, revising, and final approval of the version to be published, and agree to be accountable for all aspects of the work.

Data availability

Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Human subjects

This narrative review did not involve any research subjects.