Skin conditions have plagued humanity since time immemorial--and while our knowledge about these diseases have advanced in leaps and bounds, there is still so much we don’t know. Among these is the highly debated question: how does nutrition affect skin health?
Let’s start with what we do know: that maintaining the health and integrity of the skin requires sufficient dietary supply of nutrients. We know that the lack of certain vitamins and minerals can manifest as a dermatological problem. And we know that eating healthy, well-balanced meals will go a long way in keeping the health and appearance of skin (as well as the rest of the body).
But the connection becomes murky when we start talking about the effects of specific types of food on the skin. But how can we tell what’s fact from fiction when there are so many people and companies claiming to have the secret to smooth, youthful, even-toned skin. With the constant barrage of directives to buy this supplement, avoid that ingredient, or follow this diet, how do we cut through the noise?
Your best bet lies in evidence-based, peer-reviewed research. Here are some facts science can tell us about to the connection between nutrition and common skin conditions:
Acne
There are many food myths surrounding acne, but not enough methodologically-sound studies to support or debunk them. The observation that there is a lower prevalence of pimples among certain ethnic groups is thought to be caused by the difference in diet. Ethnic food is usually fresh, local, and cooked in healthier methods than the typical high-sugar, high-fat diet of Western societies. However, diet is not the only factor to consider. It is difficult to create a study that controls the other differences that exist between groups of people, including pollution, genes, stress, and sun exposure.
Dairy products and chocolate have long been thought to exacerbate acne. From a biological perspective, this makes some sense. We know that overactive sebaceous glands contribute to the development of zits, and that the activity of these glands is increased under the influence of dihydrotestosterone. Milk contains hormones that are precursors of dihydrotestosterone, and hormones that increase levels of dihydrotestosterone. In the process of digesting and absorbing cow’s milk, these hormones can influence the formation of acne.
But the studies that tried to confirm this cannot guarantee that drinking milk definitely causes acne. For one, many of the studies that linked dairy to acne were based on memory of what food the participants ate and self-assessment about acne. It is difficult to confirm how much of the information given is accurate. There is also research that appears to disprove the theory: One study found that only 7.7% of the participants who reported drinking 2-3 glasses of milk per day had acne. Another study found that breakouts were more prevalent among those who drank skim milk--but the hormones that were thought to influence pimple formation via dihydrotestosterone are present in the fatty portion of milk, the very same portion that is removed when skim milk is produced.
People have also pointed the finger at high-glycemic index diets and chocolates as causes of acne. There are animal and human studies that appear to show increased fat and carbohydrate intake leads to more oil production. However, the few studies that delve deeper into the issue were not able to establish that eating a high-glycemic index diet invariably leads to more clogged pores and acne. Again, the search for answers is thwarted by difficulty in controlling the influence of other food, the duration of study, follow-ups with participants, and ethical considerations in feeding a diet that has known risks to overall health.
Psoriasis
Psoriasis is an inflammatory condition that leads to skin thickening, erythema, and dryness. The existing evidence shows that it is an autoimmune disorder influenced by both genetic and environmental influences. The bad news is, there is no drug or therapy that will guarantee complete resolution of the disease. In addition, research shows that psoriasis patients are more likely to have other health conditions compared to the general population. This includes arthritis, inflammatory bowel disease, obesity, diabetes, hypertension, liver problems, pustulosis, and gout.
While changing one’s diet will not rid a patient of their psoriasis, it does provide several benefits. Three separate studies found that a low-calorie diet improved response to conventional psoriasis medical treatment. Gluten-free diet was found to significantly lower the severity and extent of lesions in psoriasis patients who tested positive for gluten autoantibodies. Consuming a vegetarian diet has been shown to alleviate symptoms. Researchers hypothesize that the increased antioxidant intake through plant-based food helps control damage from psoriasis-related inflammation. In addition, avoiding meat helps decrease the formation of pro-inflammatory eicosanoids that could trigger the condition.
Psoriasis patients would likely benefit from dietary intervention as a supplement to conventional medical therapy. It is important to consult a doctor prior to starting any new diet to make sure it is appropriate to the patient’s condition, existing comorbidities, and current medication.
Rosacea
Rosacea is an inflammatory condition that can be triggered by a wide variety of stimuli--including food. Based on anecdotal evidence and large-scale surveys among rosacea patients, it appears that certain types of foods can induce flare-ups. In a study done by the National Rosacea Society, the most common culprits include hot drinks, alcohol, spicy food and condiments, and food that contains cinnamaldehyde (including citrus fruits, cinnamon, tomatoes, and chocolates).
One of the pillars of rosacea management is minimizing exposure to triggers. Dietary intervention by avoiding the above-mentioned foods can help decrease incidence of flare-ups.
Prompted by the observation that rosacea patients are often diagnosed with Helicobacter pylori infection, small intestinal bacterial overgrowth, and inflammatory bowel disease, researchers are currently delving into the possible connection between gut health and rosacea. All these conditions point to imbalances in the gut microbiome, so there may be some benefit to taking supplements that address these issues. These include prebiotics, probiotics, and increased dietary fiber.
Eczema
Eczema, also known as dermatitis, is a group of skin conditions that are characterized by inflamed skin that can be caused by anything from direct contact with an allergen or chemicals, friction, bacterial or fungal infection, among others. There is also atopic dermatitis, which is influenced by both genetics and environmental factors.
The connection between food and eczema appears to be more plausible in infants and children rather than in adults. Pediatric eczema is known to occur in tandem with other inflammatory conditions, including food allergies.
There are several ways that food can trigger eczema episodes--it can be facilitated by immunoglobulins or white blood cells, symptoms can occur immediately or can be delayed, it could be caused by eating the food or touching it. In some children, food may exacerbate the condition, while in others, food may be the direct cause of it.
Food allergens can differ from child to child, but some common triggers include citrus fruit, tomatoes, eggs, dairy, peanuts, and tree nuts. Prick allergen tests and IgE tests in combination with physician-supervised food trials can help parents find what their child is reacting to.
In some cases of pediatric eczema, going on a diet that eliminates the allergen can help improve symptoms. However, proper diagnosis and medical supervision is essential. Children need a complete and balanced diet to feed their growing bodies. This makes them susceptible to medical issues caused by nutritional deficiencies.
This content is for general information only and is not a substitute for medical advice.
References:
Davidovici, B. B., & Wolf, R. (2010). The role of diet in acne: facts and controversies. Clinics in dermatology, 28(1), 12–16. https://doi.org/10.1016/j.clindermatol.2009.03.010
Duarte, Gleison & Barbosa, Luan & Rosa, Maria. (2012). The management of psoriasis through diet. Psoriasis: Targets and Therapy. 2012:2. 45-53. 10.2147/PTT.S24755.
Katta, R., & Schlichte, M. (2014). Diet and dermatitis: food triggers. The Journal of clinical and aesthetic dermatology, 7(3), 30–36.
Pappas A. (2009). The relationship of diet and acne: A review. Dermato-endocrinology, 1(5), 262–267. https://doi.org/10.4161/derm.1.5.10192
Passi, S. & Pità, O. & Cocchi, Massimo. (2004). Psoriasis and diet. Progress in Nutrition. 6. 231-247.
Weiss, E., & Katta, R. (2017). Diet and rosacea: the role of dietary change in the management of rosacea. Dermatology practical & conceptual, 7(4), 31–37. https://doi.org/10.5826/dpc.0704a08
