By Carol A. Kemper, MD, FACP

Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center

Dr. Kemper reports no financial relationships relevant to this field of study.

Think You Don’t Smell?

SOURCE: Fleming A. ‘I don’t smell!’ Meet the people who have stopped washing. The Guardian Aug. 5, 2019.

The eco-revolution has spawned some interesting theories and crazy ideas. Not only do we have the paleo diet, but now we have paleo bathing or, rather, non-bathing. Concerns have been raised that soaps are harmful to the skin, its natural odors, and its natural microbiome, leaving skin open to diseases such as acne and eczema and even bacterial super-infection. Indeed, certain soaps and the overuse of hot water can lead to dry skin and alter its pH.

Not only are a growing number of people forgoing deodorants and soaps, some have gone from washing once a day to once a week or have stopped bathing altogether. Several companies are answering the call for “natural” skin care products intended to restore the normal skin oils and bacteria, including a burgeoning probiotic skin care industry. One French company uses heat deactivated lactobacillus in a lotion, while another United States-based company suspends microorganisms in a gel product.

After watching horses rolling in the dirt, one inventor harvested dirt samples from a local farm, attempted to analyze their function, and concluded that certain strains of bacteria that convert ammonia to nitrogen are necessary for maintaining a pleasant body odor. He created a “Motherdirt” mist spray containing a designated strain of ammonia-oxidizing bacteria to restore natural body odor. Now there are even “pre-biotics,” which are intended to nurture the skin’s existing microbes.

What is interesting is that many of these non-bathers claim they don’t smell. However, our brains literally filter out our own body’s odors and its byproducts. That is why the bathroom always smells worse after someone else uses it. Of course, these non-bathers have an odor; they just don’t smell it themselves!

It is true that many mammals and birds survive without a hot shower and instead take “dust baths,” the purpose of which has been debated for years. Studies suggest these may be one way to thermoregulate or rid the body of ectoparasites by literally knocking them off or smothering them with dust. Birds may use dust or dirt baths to remove excess oils from feathers so that they are fluffier and provide better insulation. But after watching my chickens roll around in the dirt, I can testify that they are not any cleaner, and they most certainly smell.

Although showering with hot water and harsh soap daily may not be optimal, studies have found that regular bathing with good soap and water reduces the risk of infection in individuals colonized with Staphylococcus aureus. I routinely advise daily baths with a good lye-based soap, a clean washcloth, and lots of sudsing, especially to those areas where bacteria accumulate (axilla, perineum, groin, gluteal crease). With simple hygienic measures and freshly laundered clothing, many patients with methicillin-susceptible S. aureus or methicillin-resistant S. aureus folliculitis or boils improve. Besides, showers are one of the clear pleasures of the modern world. As the fictional time-traveling Claire Fraser of the “Outlander” series says, in choosing between the attractions of her 23-year-old husband in the 18th century and the benefits of living in the 20th century, hot showers almost won.

One-Fifth of Adults Have a Food Allergy

SOURCE: Gupta RS, Warren CM, Smith BM, et al. Prevalence and severity of food allergies among US adults. JAMA Netw Open 2019;2:e185630.

Are 19% of United States adults really allergic to a food? This survey, conducted by the non-partisan and objective research organization NORC at the University of Chicago from 2015-2016, is an extension of a national survey of food allergies conducted in children from 2009-2010. The primary outcome measure was the prevalence and severity of a convincing food allergy, based on the presence of at least one symptom on a stringent symptom list in adults in the United States. Food intolerance or symptoms not included in the expert panel’s list of stringent symptoms were excluded. The survey was completed by 40,443 adults, with a mean age of 46.6 years.

Remarkably, 19% of adults reported at least one convincing or non-convincing food allergy. Among adults with a convincing food allergy, nearly half (48%) reported developing at least one food allergy in adulthood, whereas the other half developed their allergy before 18 years of age. Slightly more than half (51%) reported “severe” food allergies, and 45% reported allergies to multiple foods. One-third reported at least one food allergy-related emergency department visit in their lifetime. Roughly half were told by a physician that they had a food allergy, and one-fourth had a prescription for epinephrine.

Women were nearly twice as likely as men to have current food allergies, and twice as likely to have developed a food allergy as an adult. The most common allergies were to shellfish (2.8%), milk (1.9%), peanuts (1.8%), tree nuts (1.2%), and fin fish (0.9%). The prevalence of food allergies did not appear to differ significantly between ethnicities, regions of residence in the United States, or household income.

Interestingly, earlier data suggested that approximately 10.8% of adults would report food allergy. This would correspond to approximately 26 million adults. Yet, this survey suggests that nearly twice as many people believe they have a food allergy to at least one food, and one-third of them have visited an emergency department for an allergic reaction to food. That’s a lot of emergency department visits.

Much remains to be learned about the frequency and consequences of food allergies in adults, which are more common than previously believed. Or at least a lot of people think they have a problem. The obvious question is whether all these people have true allergies, or just think they do or, worse, were convinced by a physician that their symptoms are the result of a food allergy and they are unnecessarily restricting their diet.