Dr Linia Patel (PhD), RD explores the role of nutrition and lifestyle on your skin and the gut-skin axis, particularly gut microbiome.
As skin deep as it sounds, first impressions count. That’s probably why so many of us put healthy, youthful, blemish-free skin at the top of our wish lists. Worrying about what to put on your skin is only half the answer to helping skin stay healthy. What you nourish your body with from the inside is just as important. As is lifestyle. Let’s explore more.
Skin physiology1,2
Your skin is the largest organ of the body, weighing in at approximately 3.6kg in adults and covering an average of around 25 square metres. It serves multiple functions. Firstly, it serves as a semi-permeable, physical barrier protecting all your organs from the external environment and from injury. It also plays a role in temperature regulation.
Very simply put, there are three layers to your skin: the epidermis, dermis and the hypodermis (fat tissue). The epidermis, the outermost layer of your skin, is a waterproof barrier, but it also creates skin tone. Underneath the epidermis, the dermis contains tough connective tissue, hair follicles and sweat glands. This layer of the skin is involved in transporting the blood. The hypodermis is the subcutaneous fat and the deepest layer of the skin. The entire skin is supported by a dense network of blood vessels, nerves and immune cells. It also includes hair follicles, sebum and sweat glands.
Is good skin in your genes?3,4
Genetics are largely responsible for your skin type (like if you have dry or normal or oily skin) and, to some extent, the speed at which your skin ages. However, even if you won the genetic lottery for your skin, environmental factors also directly influence how your skin looks and how, over time, your genes will be expressed – all factors that influence your skin’s overall health and appearance.
Your skin changes with age just as consistently as the rest of your body. Over time, skin cell turnover slows down and collagen production declines, leading to thinning, drying skin and uneven pigmentation. At a functional level, your skin becomes less effective at healing wounds and at acting as a protective barrier as you age – it loses its volume and plumpness.
They say wrinkles tell the story of how you have lived out your life; however, how skin ages is one aspect where genetics does come into play, as some differences are seen across ethnicities. For example, those with darker skin tones, such as Black Africans or South Asians, have more melanin, which provides some protection against UV radiation and often results in fewer wrinkles and a slower appearance of fine lines over time.
In contrast, those with lighter skin, such as Caucasians, tend to show signs of ageing earlier, including wrinkles, age spots and a loss of elasticity, due to less melanin and a thinner dermis. East Asian skin, like Chinese or Japanese, often ages gracefully with minimal wrinkling, but they may develop age spots and pigmentation issues over time. However, regardless of the genes, it’s important to remember the impact and importance of environmental factors.
Nourishing your skin from the inside: the gut-skin axis5,6,7
Your skin can be one of the first hints of your inner health. Scientists for a long time have linked some skin conditions to gut issues and vice versa. For example, people who suffer with inflammatory bowel disease may also experience atopic dermatitis (eczema) and psoriasis. Similarly, people who have celiac disease have a higher risk of developing psoriasis, eczema or rosacea too. In more recent years, research has shown that the link is through a complex gut-skin axis. Although scientists are confident of the existence of this axis, exactly how your skin and gut communicate and how this in turn impacts overall health is still an evolving field. However, there have been some theories proposed.
“There is no strong evidence to show that chocolate causes acne”
The first theory involves inflammation. The bacteria in your gut play an important role in regulating your immune system and inflammation is part of your immune system’s first line of defence. If inflammation becomes chronic (i.e., continues for a long period) it can cause damage. Many skin conditions like acne, eczema and psoriasis involve chronic inflammation.
Reducing inflammation therefore becomes an important aspect of ensuring good skin health. And this is where another theory comes in. Short-chain fatty acids (SCFAs) are produced as a byproduct of the bacteria in your gut feeding on a type of fibre found in foods called prebiotics. One SCFA called butyrate has an anti-inflammatory effect. SCFAs have a wide range of beneficial effects throughout the body, including healthier skin. However, scientists still don’t know how much of the gut’s SCFA reaches the skin and how this varies from person to person. Add to this the fact that bacteria in your skin’s microbiome are also thought to produce SCFAs too, which makes it all the trickier to unpick how much influence SCFA from your gut might have on your skin.
While the field continues to evolve, what we do know is having a healthy, varied gut microbiome is good for your overall health and might also benefit your skin in some ways, particularly if you have inflamed skin.
The science on nutrition for your skin7,8,9,10
The food you eat has an important role in providing your skin with the right nutrients and plays a role in indirectly managing skin conditions. Both what we eat, and our overall body fat, also play a role in sebum production, hormones and inflammation, which can then influence your skin.
Some evidence also suggests that following a whole food diet that is rich in plant-based foods may help slow down skin ageing. A balanced and nutritional diet that is rich in antioxidants, vitamins and minerals provides nutrients that help fight free radicals that break down the skin’s elastin, produce collagen and repair skin damage.
One recent study looking a group of 50 male and female subjects with psoriasis found that following a Mediterranean diet more closely was linked to having fewer flare-up symptoms. Researchers have also hypothesised that diet may play a part in the pathogenesis of acne vulgarus. A study including 32 participants with mild-moderate acne demonstrated the importance of eating whole food wholegrain carbohydrates.
Subjects in the group were randomised to either a low-glycaemic index diet (i.e., whole food, whole grain carbohydrates) or a high-glycaemic load diet (i.e., refined carbohydrates or food with added sugar) for 10 weeks. Those on a low-glycaemic load diet were found to have a significant reduction in lesion counts, more minor sebaceous glands, decreased inflammation and reduced acne severity grading overall.
“Sleep increases blood flow to the skin and this rebuilds collagen”
This study is in line with many others that suggest that a diet that is excessively high in refined carbohydrates and added sugars raises blood glucose levels which then can cause the body to produce more insulin, which in turn stimulates sebum production and sebaceous cell proliferation, which trigger acne. The good news for chocolate lovers is that there is no strong evidence to show that chocolate causes acne. That said, milk chocolate is high in fat and sugar, so should always be eaten in moderation.
The role of dairy products in skin health is highly debated. It is thought that dairy may aggravate acne on several levels through increased oil production and inflammation; however, overall, the jury is still out as there appears to be significant person-to-person variation, possibly linked back to the gut-skin axis. A meta-analysis of 14 observational studies that have looked at the relationship between milk and dairy products and acne development did find a positive relationship between all dairy milk consumption (whole milk, low fat and skimmed milk) and acne.
The analysis reported no significant relationship between yogurt and cheese and acne development. However, other research appears to show no link! Overall, recommendations point to further investigations, including the gold standard randomised controlled trials, to fully understand the links.
In supplement terms, one of the most common ones linked to skin has been collagen. As we age, the production of collagen slows down and we also produce lower quality collagen. This process starts in our late 20s and is probably most noticeable in our skin as fine lines and wrinkles begin to appear. Other noticeable signs of collagen degradation include less agile and achy joints (as the cartilage degrades), brittle hair and nails, digestion issues and perhaps more pronounced cellulite.
Women during the menopause will experience these changes more profoundly due to changes in hormones, particularly oestrogen. As collagen is a new topic of study, the first thing to point out is that the research on it is limited. Human studies are lacking, but some recent randomised controlled trials have found that collagen supplements improve skin elasticity. What is important to note is that the supplements given in this study included other nutrients like vitamin C, zinc, biotin and vitamin E, so it could have been the collagen peptides or all the nutrients together having a positive effect on the skin. What’s more, it is still very unclear what dose of collagen is optimal. It also seems to be that, once you pop collagen supplements, to keep the benefits you must keep popping!
Lifestyle factors8,9,10,11
What you eat matters; however, so does how you live. A study comparing almost 200 sets of identical twins showed that sun damage, pollution and smoking can add years to your skin. You therefore also need to think about feeding your skin from the outside too.
One of the most important things you need to consider is protecting yourself from the sun. While ultraviolet light is invisible, the powerful rays radiate from the sun and can damage the collagen and elastin in your skin, causing your skin to look less supple and more wrinkled. UV exposure is responsible for 80% of visible facial ageing signs like deep fine wrinkles and pigmentation. Wearing sunscreen is a good way to protect your skin from sun damage.
Smoking is not good for your health, including your skin. Smoking speeds up the normal ageing process of your skin. Toxins in the smoke stop the skin from producing as much collagen, which then contributes to wrinkles. Protect your skin by stopping smoking.
Similarly, studies have shown that too much stress can affect your skin health too. Divorced women in one study appeared 1.7 years older than their identical twins, possibly due to stress. Some research suggests that people with acne have an over-active cortisol (stress hormone) secretion system, one that is particularly expressed in sebaceous glands. Thus, stress (plus inflammation) can make acne or psoriasis worse.
Beauty sleep is a real thing! Poor sleep means the skin ages faster. It doesn’t recover so well from stresses like sun damage and dehydration because the regeneration isn’t happening. When you sleep well, the epidermis, the layer under the skin, gets regenerated. Sleep increases blood flow to our organs, particularly the skin, and this rebuilds collagen, which then plumps up the skin and reduces the damage done by sun exposure. Being active also improves blood flow to the skin’s surface and will give your skin a rosy glow.
Five steps to nourish your skin
The outer layer of your skin, called the epidermis, renews itself every 28-31 days. The turnover of skin cells requires adequate hydration and enough lean protein, wholegrain carbohydrates and healthy fats, as well as a variety of micronutrients, vitamins and antioxidants. Here are ways to ensure that you nourish your skin:
1. Stay hydrated.
Healthy skin needs good hydration. Dehydrated skin is more likely to develop wrinkles as it stops being so elastic. Aim to drink 1.5-2 litres of water per day.
2. Find your balance.
No one food group can supply all the nutrients that your skin and body need; therefore, the key is to eat a balanced, nutrient-rich diet, which is rich in antioxidants, vitamins and minerals. Vitamins A, B2, B3, B6, C, D, E, Zinc and selenium are important for optimal skin health and function.
3. Go easy on the booze.
Too much alcohol can dry out your skin. If you choose to drink, you should always have enough water alongside alcohol. Drink in moderation and stay below the government guidelines. Spread your drinking over three days or more if you drink as many as 14 units per week.
4. Eat the rainbow.
Diets rich in antioxidants will help fight free radicals that break down the skin’s elastin, produce collagen and repair skin damage; however, there is also exciting work around topical antioxidants.
5. Add in healthy fats.
Fats found in foods like avocado, extra virgin olive oil, nuts and seeds help to moisturise and protect your skin. Omega-3 fatty acids found in oily fish and in plant sources, such as flaxseed, linseeds, walnuts and rapeseed oil, are also known to be anti-inflammatory, which may be beneficial for inflammatory skin conditions like eczema and psoriasis.
Dive into Dr Linia Patel’s blog post on longevity through nutrition.
References
- Cao C et al (2020), Diet and Skin Aging. From the perspective of food nutrition, Nutrients, 12: 870.
- British Dietetic Association Fact Sheets: Skin. Accessed here: https://www.bda.uk.com/resource/skin-health.html#:~:text=Feeding%20your%20skin%20from%20the%20inside&text=So%2C%20eating%20a%20balanced%20nutritional,cause%20medically%20recognised%20skin%20problems, accessed on 24 October 2024.
- Makrantonaki E et al (2012), Genetics and skin aging, Detmatoendrocrinol., 1: 4(3): 280-384.
- Flament F et al (2013), Effect of the sun on visible clinical signs of aging in Caucasian skin, Lin Cosmet Investig Dermatol., 6: 221-232.
- Ying et al (2014), Brain-skin connection: Stress, inflammation and skin ageing, Inflamm Allergy Drug Targets, 13(3): 177-190.
- Pessemier B et al (2021), Gut-Skin Axis: Current knowledge of the interrelationship between microbial dysbiosis and skin conditions, Microorganisms, 9(2): 353.
- Solway J et al (2020), Diet and Dermatology: The role of a whole-food plant-based diet in preventing and reversing skin aging – a review, J Clin Aesthet Dermatol., 13(5): 38-43.
- Barrea L (2015), Nutrition and psoriasis: Is there any association between the severity of the disease and adherence to the Mediterranean diet? Journal of Translational Medicine, 13(18).
- Guyuron et al (2009), Factors contributing to the facial aging of identical twins, Plastic and Reconstructive Surgery, 123(4): 1,321-31.
- Ristow et al (2011), Extending life span by increasing oxidative stress, Free Radic Biol.
- Me Bolke L, Schlippe G, Gerß J, Voss WA (2019), Collagen supplement improves skin hydration, elasticity, roughness, and density: Results of a randomized, placebo-controlled, blind study, Nutrients, 11(10): 2494.d. 51:327-36.
