Beware the Hidden Allergens in Nutritional Supplements

Consider popular nutritional supplements as a potential source of allergic reactions if the cause of the reaction is otherwise unknown, Alison Ehrlich, MDsaid at the annual meeting of the American Contact Dermatitis Society.

Dr Alison Ehrlich

Allergens may be hidden in a range of supplement products, from colorings in vitamin C powders to some vitamins used in hair products and other products.

“In general, our patients do not tell us what supplements they are taking,” said Ehrlich, a dermatologist who practices in Washington, DC. Antiaging, sleep, and weight loss/weight control supplements are among the most popular, she said.

Surveys have shown that many patients do not discuss supplement use with their healthcare providers, in part because they believe their providers would disapprove of supplement use, and patients are not educated about supplements, she said.

“This is definitely an area that we should try to learn more about,” she added.

Current regulations regarding dietary supplements stem from the Dietary Supplement Health and Education Act of 1994 (DSHEA), which defined dietary supplements as distinct from meals but regulated them as a category of food, not as medications. Dietary supplements can be vitamins, minerals, herbs, and extracts, said Ehrlich.

“There is not a lot of safety wrapped around how supplements come onto the market,” she explained. “It is not the manufacturer’s responsibility to test these products and make sure they are safe. When they get pulled off the market, it is because safety reports are getting back to the FDA.”

Consequently, a detailed history of supplement use is important, as it may reveal possible allergens as the cause of previously unidentified reactions, she said.

Ehrlich shared a case involving a patient who claimed to have had a reaction to a “Prevage-like” product that was labeled as a crepe repair cream. Listed among the product’s ingredients was idebenonea synthetic version of the popular antioxidant known as Coenzyme Q.

Be Wary of Vitamins

Another potential source of allergy is vitamin C supplements, which became especially popular during the pandemic as people sought additional immune system support, Ehrlich noted. “What kind of vitamin C product our patients are taking is important,” she said. For example, some vitamin C powders contain coloring agents, such as carmine. Some also contain gelatin, which may cause an allergic reaction in individuals with alpha-gal syndrome, she added.

In general, water-soluble vitamins such as vitamins B1 to B9, B12, and C are more likely to cause an immediate reaction, said Ehrlich. Fat-soluble vitamins, such as vitamins A, D, E, and K, are more likely to cause a delayed reaction of allergic contact dermatitis (ACD).

Ehrlich described some unusual reactions to vitamins that have been reported, including a systemic allergy associated with vitamin B1 (thiamine), burning mouth syndrome associated with vitamin B3 (nicotinate), contact urticaria associated with vitamin B5 (panthenol), systemic allergy and generalized ACD associated with vitamin E (tocopherol), and erythema multiforme–like ACD associated with vitamin K1.

Notably, vitamin B5 has been associated with ACD as an ingredient in hair products, moisturizers, and wound care products, as well as B-complex vitamins and fortified foods, Ehrlich said.

Herbs and spices can act as allergens as well. Turmeric is a spice that has become a popular supplement ingredient, said Ehrlich. Turmeric and curcumin (found in turmeric) can be used as a dye for its yellow color as well as a flavoring but has been associated with allergic reactions. Another popular herbal supplement, ginkgo bilobahas been marketed as a product that improves memory and cognition. It is available in pill form and in herbal teas.

“It’s really important to think about what herbal products our patients are taking, and not just in pill form,” Ehrlich said. “We need to expand our thoughts on what the herbs are in.”

Consider Food Additives as Allergens

Food additives, in the form of colorants, preservatives, or flavoring agents, can cause allergic reactions, Ehrlich noted.

The question of whether food-additive contact sensitivity has a role in the occurrence of atopic dermatitis (AD) in children remains unclear, Ehrlich said. However, a study published in 2020 found that 62% of children with AD had positive patch test reactions to at least one food-additive allergen, compared with 20% of children without AD. The additives responsible for the most reactions were azorubine (24.4%), formic acid (15.6%), and carmine, cochineal red, and amaranth (13.3% for each).

Common colorant culprits in allergic reactions include carmine, annatto, tartrazine, and spices (such as paprika and saffron), said Ehrlich. Carmine is used in meat to prevent photo-oxidation and to preserve a red color, and it has other uses as well, she said. Carmine has been associated with ACD, AD flares, and immediate hypersensitivity. Annatto is used in foods, including processed foods, butter, and cheese, to provide a yellow color. It is also found in some lipsticks and has been associated with urticaria and angioedemashe noted.

Food preservatives that have been associated with allergic reactions include butylated hydroxyanisole and sulfites, said Ehrlich. Sulfites are used to prevent food from turning brown, and it may be present in dried fruit, fruit juice, molasses, pickled foods, vinegar, and wine.

Reports of ACD in response to sodium metabisulfite have been increasing, she noted. Other sulfite reactions may occur with exposure to other products, such as cosmetics, body washes, and swimming pool water, she said.

Awareness of allergens in supplements is important “because the number of our patients taking supplements for different reasons is increasing” and allergens in supplements could account for flares, Ehrlich said. Clinicians should encourage patients to tell them what supplements they use. Clinicians should review the ingredients in these supplements with their patients to identify potential allergens that may be causing reactions, she advised.

Ehrlich has disclosed no relevant financial relationships.

American Contact Dermatitis Society Annual Meeting: Presented March 16, 2023.

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