Diet and Skin Conditions

Diet and skin conditions have been a hot topic in the last decade among dermatologists. This article is a summary of a 2018 overview published in SkinTherapyLetter: Skin and Diet: An Update on the Role of Dietary Change as a Treatment Strategy for Skin Disease. We focus in on acne, atopic dermatitis, psoriasis, rosacea, and aging skin, and the effects that diet may have on people with these conditions.

The relationship between diet and skin conditions has long been debated. Traditionally, the dermatology community has been more skeptical about the relationship between diet and skin conditions than the general public, partly due to a lack of clinical data and the challenge of isolating data from numerous other factors. Today, more evidence is emerging that supports the idea that diet plays a role in influencing various skin conditions. This study provides a comprehensive overview of recent literature on the role of diet on five common skin conditions: Acne, Atopic Dermatitis, Psoriasis, Rosacea, and Aging Skin.

Acne

Dietary change has long been considered an essential factor in acne – both for triggering acne and treating acne. While this link was viewed with skepticism in the dermatology community for some time today, it is finding new attention. At DermLetter, we have an article that summarizes the seminal study that linked acne and diet.

Triggers:

• The strongest evidence supporting the relationship between diet and acne is with high glycemic foods exacerbating acne symptoms.
• A low glycemic diet for 12 weeks has been tried in clinical trials and has shown some evidence of efficacy.¹
• Skin inflammation and sebaceous gland size were decreased in a histopathological examination after a 10-week random control trial.²
• There is some evidence of a link between acne and dairy consumption.³

Treatments:

• Despite a plethora of anecdotal claims, studies are currently largely limited to in-vitro studies and animal studies.⁴ Human studies are extremely limited.
• A few substances are mentioned as being of potential interest for further study: Omega 3 fatty acids, probiotics, and zinc.⁵

Atopic Dermatitis:

The evidence for direct and causal links between diet, allergies, and atopic dermatitis is strong. Food allergies are another area where the diet is connected with atopic dermatitis, especially in children and in patients with severe cases.

Triggers:

• Food allergies are strongly connected with atopic dermatitis.
• Foods may trigger atopic dermatitis flares through 3 mechanisms: IgE or Type I sensitivity (minutes to hours), late eczematous triggered reactions (48 hours), T-cell mediated reactions, also called systemic contact dermatitis (which can be found via patch testing).⁶

Treatments:

• Synbiotics (probiotics + prebiotics) show promise in treating atopic dermatitis. Probiotics are live bacteria similar to those found in the body. Prebiotics are nondigestible carbohydrates that stimulate the growth of probiotics in the intestine.
• Vitamin D has not shown any promise except when patients may be deficient or in patients with frequent bacterial infections.⁷
• Primrose oil, borage seed oil, Chinese herbal medicine has shown little to no efficacy,⁸ while the research on fish oil supplements is limited.⁹

Psoriasis:

Psoriasis and diet have long been associated, but the more clear relationship is between psoriasis and high body mass index (BMI). The reasons for this are multifactorial, and obesity likely predisposes to psoriasis and vice versa.¹⁰ Currently, the focus is on weight loss – the exact mechanisms of the link between weight and psoriasis are still unknown.

Triggers:

• Weight is an important factor in psoriasis. Diabetes, hypertension, and cardiovascular disease are all associated with psoriasis, unusually severe psoriasis. Dietary change leading to weight loss has improved treatment efficacy and PASI (psoriasis area severity index).
• Smoking and alcohol intake is also associated with psoriasis and psoriatic arthritis.¹¹
• Gluten sensitivity may play a factor in some psoriasis patients. One meta-analysis found a 2.2 fold higher risk of celiac disease compared to controls in psoriasis patients.¹² More research will be needed, but checking for celiac antibodies may be warranted in some patients.

Treatments:

• Weight loss intervention is effective, and the evidence supporting it is strong. It also increases the therapeutic efficacy of systemic therapy and biologics.
• In terms of nutritional supplements, fish oil and oral vitamin D shows the most promise, while the evidence for vitamin B12 and selenium is limited at this time.
• At this time, there are no specific dietary guidelines established.

Rosacea:

Dermatologists generally accept that diet is frequently a trigger for rosacea flares. Most rosacea patients corroborate this from their personal experience. In a survey from the National Rosacea Society, 78% had altered that diet, and 95% of this group reported a subsequent reduction in flares.¹³

Triggers:

• Spices (75%), hot sauce (54%), wine (52%), hot beverages like coffee (33%) and tea (30%), tomatoes (30%), chocolate (23%), citrus (22%)¹³ are frequently cited triggers that worsen rosacea symptoms.
• The mechanism for triggers is unknown, except that TRP (transient receptor potential) channels may play a role.
• Capsaicin and cinnamaldehyde, which act on these channels, stimulate an increase in skin blood flow. These are found in spices, cinnamon, tomatoes, citrus, and chocolate and maybe the reason for triggering symptoms.

Treatments:

• Gut bacteria and skin may have a connection in rosacea. Supporting this are correlations with rosacea and celiac disease, Crohn’s disease, ulcerative colitis, Helicobacter pylori infection, and small intestinal bacterial overgrowth (SIBO).¹⁴
• The exact causative link is unknown at this time. Some studies found rosacea patients were far more likely to have small intestinal bacterial overgrowth (SIBO).

Aging Skin:

Aging skin affects everyone. It is the most general of skin concerns, in a sense. Although sun damage is by far the most important environmental factor for skin aging, the influence of diet on skin aging has long been recognized.

Triggers:

• Lifestyle factors have long been recognized as being connected with skin aging. The most commonly discussed factors are sun protection, but dietary factors may also play an important role.
• High blood sugar levels can produce advanced glycation end products, leading to a loss of elasticity in the skin.
• Certain cooking processes like deep frying can also be detrimental, as it creates advanced glycation end products.¹⁵
• Glucose level increases correlate with perceived age increase.

Treatments:

• There is strong evidence from laboratory and animal studies for the beneficial effects of antioxidants in foods ranging from vegetables, fruits, tea leaves, and seeds, limiting UV damage. The data is more limited in human studies.¹⁵
• Diets high in phytonutrients can limit photodamage. One study reported a higher intake of vegetables, legumes, and olive oil protects against actinic damage.¹⁶
• Dietary sources of antioxidants appear to function differently from those found in supplements.
• Diets high in potassium and vitamin A and C are correlated to fewer wrinkles.

Discussion:

That’s a lot to unpack, as this study is a very general overview of the recent literature relating to diet and skin conditions. There are few conclusive and specific recommendations based on skin conditions, as it is challenging to isolate something as general as food intake from other factors that play a role under clinical conditions.¹⁷ What works for one patient may not work for another. However, for patients with specific skin conditions, this provides a great starting point to experiment with to potentially reduce symptoms.

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¹⁷http://fivethirtyeight.com/features/you-cant-trust-what-you-read-about-nutrition/