This piece was written in partnership between founder of The Food Medic and nutritionist – Dr Hazel Wallace; and our resident dietitian – Maeve Hanan.
There are many messages about how to improve our skin through our diet or supplements. This article will explore evidence-based advice for the role of nutrition in keeping our skin healthy, as well as the role of nutrition in specific skin conditions (acne, eczema, rosacea and psoriasis).
Eating well for healthy skin
A number of different factors impact our skin, including genetics, age, hormones, medication, stress, sleep, movement, skincare routine, exposure to UV rays, pollution and smoking.
Nutrition is one of these factors, as good nutrition plays a role in keeping all of our organs healthy, and our skin is the biggest organ in the body. However, the role of nutrition is sometimes overstated when it comes to skin health. For example, even though eating well supports healthy skin, it won’t alter genetic predispositions, reverse UV damage or prevent the natural ageing process.
With that being said, there are a number of nutrients that play an important role in skin health (1, 2):
- Protein: Dietary protein provides amino acids which the body uses to make proteins that play an important role in the structure of our skin, such as keratin, elastin and collagen. Good sources include; meat, poultry, seafood, eggs, dairy, beans, pulses, nuts (including nut butter!), seeds and soya-based products like tofu, and protein supplementation (e.g. whey or vegan blends). Collagen is an important protein that is found in our skin. Some recent studies have suggested that taking hydrolysed collagen supplements may help to reduce wrinkles and improve skin health, however this evidence is currently quite weak. Check out this article for more information about collagen supplements.
- Essential fatty acids (omega-3 and omega-6 fatty acids): Found in oily fish (like salmon, mackerel, herring, trout, sardines and pilchards), walnuts, flaxseeds, chia seeds, vegetable oils and tofu. These are involved in building our outer layer of skin, which helps to form our skin’s barrier and maintain moisture in the skin (3). Omega-3’ has anti-inflammatory properties which may also benefit skin health (4).
- Vitamin C: Found in oranges, strawberries, kiwis, peppers, tomatoes, broccoli and potatoes. This vitamin is involved in creating collagen which provides structure to the skin. It is also an antioxidant and is involved in wound healing (5).
- Vitamin E: Found in a variety of nuts and seeds, leafy green vegetables, sunflower oil, safflower oil and in certain fortified foods. Vitamin E protects the skin as it is an antioxidant, it may offer some protection against UV rays (6).
- Vitamin A: Present in the form of retinol in liver, dairy products, eggs, salmon and in the form of beta-carotene in green leafy vegetables, carrots, peppers, sweet potato, apricot and mango. This vitamin is an antioxidant and is also needed for cell growth and turnover. Note: if you’re pregnant, you should avoid liver or liver pâté, because these are very high in vitamin A, and having large amounts of vitamin A can harm your unborn baby. For this reason you should avoid supplements containing vitamin A also.
- B-vitamins (including riboflavin, niacin, biotin and vitamin B6): These vitamins are found in a variety of foods such as wholegrains, nuts, seeds, meat, offal, poultry, seafood, dairy, eggs, vegetables and fortified foods. A lack of these B-vitamins can lead to inflamed skin, dermatitis, rashes and cracks in the skin at the corners of the mouth.
- Zinc: Found in red meat, oysters, crab, lobster, poultry, dairy products, beans, nuts, wholegrains and fortified breakfast cereals. Zinc plays an important role in wound healing and reducing UV damage (2, 7).
- Selenium: Found in meat, poultry, seafood, eggs, dairy products, Brazil nuts, seeds and wholegrains. Selenium protects the skin by acting as an antioxidant.
Underfuelling by not eating enough overall calories is also linked with skin issues such as dry and itchy skin, dermatitis and delayed wound healing (8).
Therefore, a balanced diet that contains enough energy and a variety of fruit, vegetables, grains, nuts, seeds, vegetable oils, fish, meat, pulses, eggs and dairy should provide all the nutrients for good skin health (1). This way of eating reflects a Mediteranean-style diet, which has also been found to have numerous health benefits for other organs such as our heart and brain.
Hydration is really important for healthy skin. Water, milk (or plant-based alternatives), tea and coffee are all great sources of fluid. Juice also counts towards our fluid intake but we are recommended to limit this to 150ml per day. Alcohol should only be consumed within the recommended low-risk limit for overall health, and to avoid dehydrating the skin (1).
There is ongoing research into the impact of a variety of supplements on skin health; but the current evidence is very limited in this area (9). So unless you have a nutrient deficiency, the only supplement that most people in the UK need to consider taking is vitamin D (which has also been found to play a role in healthy skin), especially during winter and for those who get limited sunshine exposure. Similarly, the evidence base related to gut health, prebiotics, probiotics and skin health remains limited; although this is an emerging area (10, 11). A balanced and varied diet will provide a good intake of prebiotics to promote gut health, and hence overall health — including skin health. Research related to supplements, probiotics and specific skin conditions will be discussed below. Check out this article for more information about probiotics.
Diet and acne
Despite a limited amount of high-quality research related to diet and acne, there are a lot of messages and diet myths related to this.
A common concern is that dairy causes acne. There are a few studies that have found a possible link between dairy and acne, but there have only been a few studies to investigate this and they don’t prove a ‘cause and effect’ link (12, 13). Interestingly, there may be a higher risk of acne with skimmed milk consumption as compared with whole milk (12, 13). So there is a possibility that milk may impact acne risk for some people, but this risk seems low. If you are making changes to your diet like trying a dairy exclusion, it is best to do this with support from a dietitian to ensure your diet remains balanced.
Another common message is that sugar causes acne. Some observational studies have found that frequently spiking blood glucose levels (i.e. a high glycaemic index/glycaemic load diet) may increase acne risk due to impact on insulin, insulin-like-growth factor-1 and acne.
However the results of these studies have been mixed, so although there may be a potential link between glycaemic load or sugar intake and acne, we certainly don’t have enough evidence to say that ‘sugar should be avoided’ (13, 14, 15). A black-and-white food rule like this can also become restrictive and obsessive, and there are other ways of reducing the glycemic load of our food such as having having sugary foods alongside foods that contain, fibre, protein and/or fat; for example, having a handful of nuts along with a few squares of chocolate.
A Mediterranean-style diet is likely to support overall skin health as discussed above. Although few studies have investigated the specific link between acne and the Mediterranean diet, the anti-inflammatory and gut-healthy properties of this way of eating may provide additional benefits in terms of acne risk and management (16, 17).
A NOTE ON GLYCAEMIC INDEX AND GLYCAEMIC LOAD
The glycemic index (or GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar (glucose) levels after eating. Glycemic load is a measure that takes into account the amount of carbohydrate in a portion of food together with how quickly it raises blood glucose levels. In general, high-GI foods are simple and refined carbohydrates, such as white bread, sweets and dried fruit, and low-GI foods are usually complex carbohydrates, like oats, brown rice and rye bread. The GI of a food also depends on the type of food, ripeness, processing, storage, cooking method and other foods that it is eaten with. It’s important to note that this is *not* a scale of how healthy a food is — high GI foods can be very nutritious e.g. a baked potato has a high GI, while a chocolate bar has a lower GI due to the fat content. So focusing on eating just low GI foods may not be beneficial for your health overall.
Diet and Eczema
Atopic eczema is associated with food allergies (i.e. when the immune system reacts unusually to the protein found in a specific food). The most common food allergies occur in response to: cow’s milk, eggs, soya, wheat, nuts or seafood. Food allergies can only be diagnosed by a qualified doctor, and should be managed with support from a registered dietitian. For those who don’t have eczema as a symptom of a specific food allergy, there is no strong evidence to support diets that eliminate common allergens (18).
For some people who experience an eczema flare-up in response to touching certain substances (like nickel, propylene glycol, chamomile, formaldehyde or Balsam of Peru), consuming food and drinks that contains these substances, either naturally or as additives, may also trigger symptoms (19). A handful of studies have also found a possible link between eczema flare-ups and foods that contain histamine; a chemical found in certain foods (like cured and aged meats and fermented food) that also interacts with our immune system (20, 21). However this evidence is very limited. If certain foods or additives are suspected as triggers for an eczema flare up, exclusion diets should only be trialled with the support of a registered dietitian.
A few studies, which have mainly focused on infants and children with eczema, have found that Lactobacillus or Bifidobacterium-containing probiotics may lead to a small improvement in symptoms (22). The results of these studies were mixed, but found no negative side-effects from trying probiotics.
As inflammation plays a central role in eczema flare-ups, a diet that contains anti-inflammatory foods like the Mediterranean diet may be helpful, although there isn’t much evidence to back this up (23). As discussed throughout this article, this Mediterranean-style diet is also good for skin health in general, as well as overall health. There is also limited evidence that antioxidants and fish oil supplements may lead to some improvement in eczema symptoms, but more studies are needed (24, 25).
Diet & Rosacea
Many people with rosacea report individual dietary triggers, although there is a lack of robust evidence to support this (26, 27, 28). A survey of 400 Rosacea patients in 2005 from the National Rosacea Society reported “78% [of participants] said they had to alter their diet to avoid rosacea flare-ups” (29). Spice was found to be the most common trigger, impacting roughly 75% of those in the survey. Other commonly reported dietary triggers for rosacea include: hot foods and drinks, alcohol, citrus fruits, peppers, chocolate, cinnamon and high-histamine foods (28, 30). A recent Chinese study also found that consuming tea and high-fat food more often was linked with a higher risk of rosacea, whereas more frequent dairy consumption was linked with a lower risk (31).
Some observational studies have suggested that promoting gut-health by consuming a high-fibre, prebiotic-containing varied diet may via the gut-skin connection (27). More studies are needed to investigate whether probiotics have a role to play.
Again, the skin-healthy, gut-healthy and anti-inflammatory effects of the Mediterranean diet may be beneficial, although direct evidence related to rosacea is lacking. There is also some limited evidence that omega-3 and zinc may have a role to play in reducing symptoms of rosacea (27).
Diet & Psoriasis
As psoriasis is an inflammatory skin condition, anti-inflammatory foods and dietary patterns may be helpful (yup, the Mediterranean diet again!) (32). In fact, the medical board of National Psoriasis Foundation recommend that adults with psoriasis should consider trialing the Mediterranean diet and increasing their intake of unsaturated fats and fibre, while consuming less saturated fat, refined carbohydrates and overall energy; although they highlight that this is based on weak evidence (33).
Based on the available evidence in 2018, the National Psoriasis Foundation do not recommend supplementing with fish oil or vitamin B12 supplements but do advise (33):
- Those with confirmed coeliac disease should follow a gluten-free diet, and those with serological markers of coeliac disease can trial a 3-month gluten-free diet, alongside standard medical treatment.
- Those with psoriatic arthritis and a BMI above 25 kg/m2 may benefit from weight reduction with a low-calorie diet, alongside standard medical treatment (please note: BMI isn’t a very accurate marker of body composition, and the pursuit of weight loss isn’t helpful for everyone).
- Those with psoriatic arthritis should try taking a daily vitamin D supplementation (containign 0.5 μg alfacalcidol or 0.5-2.0 μg calcitriol) alongside standard medical treatment.
- There is not enough evidence to give a recommendation related to selenium supplements or combination micronutrient supplements.
Consuming a lot of alcohol has also been linked with more severe and a higher risk of psoriasis, as this may interfere with inflammatory pathways and the skin’s barrier function (34). There is also some emerging research that has found probiotics may be useful in the management of psoriasis (35, 36). But more studies are needed to investigate the possible impact of alcohol and probiotics in relation to psoriasis.
Summary
From a nutritional point of view, we can support the health of our skin by following a varied Mediterranean-style diet, consuming enough energy, staying hydrated and not drinking too much alcohol. There are a number of dietary considerations for the management of acne, eczema, rosacea and psoriasis — but a lot of this advice also comes back to a anti-inflammatory, gut-friendly way of eating, like the Mediterranean diet. Importantly, there are a number of factors that impact our skin beyond diet, so always follow individualised advice for your medical needs.
References
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