Inside-out skincare: nutrition for skin health

In this blog our guest writer, Fiona Lawson – a nutritionist, researcher and skin specialist – shares her nutrition advice for supporting skin health.

We knew that diet affected skin before we could even define nutrients. In the mid-18th century, British sailors dreaded the bleeding gums, skin haemorrhages and bruising that could develop on long voyages. In one of the earliest clinical trials recorded, Scottish physician James Lind determined that giving sailors a ration of citrus fruit would help prevent these symptoms from appearing. It would be another 181 years before vitamin C was isolated and identified, but now we know this condition to be scurvy and vitamin C – rich in citrus fruit – to be the cure.

This connection is just one example of how changes in nutritional status can alter skin structure, function and appearance. Research on this topic has ramped up since the turn of this century— and we now have a much clearer picture of how nutrition can influence our skin health.

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Structure and function of the skin

Most of us know that the skin is our largest organ, but few of us realise it encompasses up to 15% of our body weight.² That means that an average 70kg woman can carry around a staggering 10.5kg of skin.

This mass of skin comprises three layers:

• The epidermis: the uppermost layer, which is responsible for many of the skin’s barrier functions. The epidermis renews itself approximately every 28 days.²
• The dermis: the middle layer, which gives the skin structure and contains the blood and lymph vessels that provide nutritive The dermis varies from 0.3mm to 4mm thick, depending on the body site.³
• The hypodermis: the lower layer, also known as the subcutaneous This layer stores energy and helps to provide insulation.

In a healthy state, these three layers are perfectly designed to fulfil a range of functions. These include:⁴

• Providing immune defence
• Harbouring free radical detoxifying enzymes and antioxidant molecules
• Controlling thermoregulation
• Preventing excessive water loss
• Allowing sensory input via mechanoreceptors
• Enabling endocrine and metabolic mechanisms, such as the production of vitamin D

These many functions require a constant flow of energy and nutrients.² Crucially, skin that functions properly is also aesthetically pleasing—giving skin a healthful appearance. As captured by Boelsma et al., “The skin plays a pivotal role in the feeling of well-being and physical attractiveness.”⁵ Research consistently shows that if our skin looks and feels less than healthy—as is the case with conditions such as acne or psoriasis—it profoundly impacts our quality of life.^6,7

The good news is that optimising your diet can dramatically influence your skin health and appearance.

Dietary patterns and skin health

Before delving into individual nutrients, it’s worth looking at the broader dietary trends that influence skin health. Research suggests that these encompass many of the foundational principles of nutritional therapy, including:

1. Prioritise nutrient-rich foods

An observational study of more than 4,000 US women aged 40–74 found that diets rich in vitamin C and linoleic acid were associated with healthier, younger-looking skin.8 In the same study, a 50g daily increase in carbohydrates was associated with an increased likelihood of a wrinkled appearance.

A further study of Anglo-Celtic, Greek and Swedish people living in either Australia or their native countries echoes these findings. This observational study showed a high intake of vegetables, olive oil and legumes (and a lower intake of sugar) were protective against cutaneous actinic damage.⁹

1. Eat the rainbow

In a cross-sectional study of 716 Japanese women, a higher intake of green and yellow vegetables was associated with less severe crow’s feet wrinkles.¹⁰ Building on this, a further pilot study hypothesised that nutrition accounts for up to 30% of wrinkle formation in Japanese women.¹

1. Be mindful of sugar intake

Glucose is the primary fuel for skin cells, so it follows that aberrant glucose handling affects skin structure and appearance.¹² It is generally accepted that consuming too much sugar can promote wrinkles, mainly due to the production of advanced glycation end products (the helpfully dubbed ‘AGEs’). ‘AGEs’ develop when a glucose molecule binds to collagen in the skin and other organs. They make collagen skin stiff, vulnerable and difficult to repair, leading to what’s known as ‘sugar sag’.¹³

In one fascinating study, higher serum glucose levels were associated with higher perceived age.¹⁴ Put more simply: the higher people’s blood-sugar levels, the older they looked to others.

It is important to note that, as with any epidemiological research, findings are equivocal and often contradictory. For example, a higher fat intake was associated with more wrinkles in the US study, while the Japanese study found the opposite.^8,9 Diet is complex, and food matrices, nutrient synergies and individual responses have influence outcomes.

Despite this, clear trends in the research to date have emerged. We can infer that eating plenty of fruits and vegetables, prioritising non-processed, low-GL sources of carbohydrates and consuming sufficient essential fats are all important for skin health and function.

Top 10 nutrients for healthy skin

In addition to general dietary patterns, research has focused on specific nutrients and nutritive compounds that promote a clear, healthy complexion. Here are ten of the most potent:

• Vitamin C

We already know that eating a diet rich in vitamin C can contribute to younger-looking skin,⁸ and it is not surprising when you consider the multifaceted functions of this nutrient.

In the epidermis, vitamin C acts as a powerful antioxidant, combatting the free radicals produced by UV rays. In the dermis, it is used as a co-factor producing and maintaining collagen.² As a key contributor to the innate and adaptive immune response, vitamin C also plays an important role in barrier integrity and wound repair—whether the skin is compromised by an acute paper cut or chronic psoriasis plaque.¹⁵

The best food sources of vitamin C include peppers, berries and (as Dr James Lind surmised) citrus fruit. In supplemental form, vitamin C is most effective when supplied with co-antioxidants.⁵

• Omega-3 fatty acids

Omega-3 fatty acids appear to play a regulatory role in the skin.

Through serving as precursors to anti-inflammatory eicosanoids, the long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can attenuate the inflammatory response.⁵ They offer a promising therapeutic tool for inflammatory skin conditions, with interventional studies suggesting that EPA/DHA supplementation can improve acne,¹⁶ and psoriasis when combined with other treatments.¹⁷

Through the same potential to suppress the inflammatory response, omega-3 fatty acids can also confer a degree of photoprotection.¹⁸

• Omega-6 fatty acids

Omega-6 fatty acids seem to have more of a structural role in the skin.

They are the most abundant polyunsaturated fatty acids in the epidermis, where animal studies suggest they contribute to the production of ceramides.^19,20 These ceramides serve as the ‘mortar’ to the keratinocyte’s ‘bricks’, maintaining the skin’s structural integrity and promoting healthy barrier function.

It makes sense that omega-6 fatty acids can help to reduce skin sensitivity. In one interventional study, 40 men and women received either 1.5g evening primrose oil (rich in the omega-6 fatty acid GLA) or placebo. After 12 weeks, those receiving evening primrose oil had significant improvements in skin moisture, elasticity, firmness and trans-epidermal water loss (a measure of barrier integrity) compared to placebo.²¹

• Zinc

This trace mineral has several roles in skin health, including processes involved in repair and maintenance.

It is so important that up to 6% of the total body concentration of zinc is found in the skin (particularly the epidermis) and, with no mechanism for long-term storage, a regular dietary intake is essential.⁴

Zinc is perhaps most well-known for its use in acne, with two reviews concluding that supplemental zinc is an effective intervention for inflammatory acne lesions.^22,23

• Vitamin D

Skin is the site of vitamin D production, but vitamin D status can also influence skin health. This pro-hormone regulates keratinocyte proliferation and differentiation, which are critical processes in skin renewal and replenishment.²⁴

Vitamin D also modulates inflammation and immune function—and vitamin D deficiency has been associated with increased risk of inflammatory skin conditions including acne,^25,26 psoriasis,²⁷ and atopic dermatitis.²⁸ Some, but not all, interventional trials suggest that supplementing with vitamin D can lead to improvement in these conditions.²⁴

• Collagen

Collagen is the most abundant protein in the human body and is responsible for structure, strength and stability in the skin.

In women, collagen synthesis declines by 30% during the first four years of menopause—and decreases by a further 2% every year after that—leading to wrinkles and other signs of ageing.²⁹ Supplementing with collagen peptides may help.30 These have a dual action in the skin: they provide the building blocks for collagen, and bind to fibroblasts in dermal layers to stimulate the synthesis of collagen, elastin and hyaluronic acid.³¹

Marine collagen tends to be the most absorbable form, with trials suggesting that 2.5–5g daily is an effective dose for skin health.^32,33

• Carotenoids

We all know excessive sun exposure can lead to skin laxity, thickening and wrinkling.³⁴ However, not all of us realise that increasing antioxidant defences in our skin cells can limit this photodamage.

Dietary carotenoids such as beta-carotene and lycopene are powerful antioxidants and, remarkably, they accumulate in the skin where they are needed most.^35,36 In one skin-analysis study, subjects received 25mg total carotenoids for 12 weeks.³⁷ At the end of the intervention, there was a 0.7-fold increase in carotenoids in dorsal skin (exposed to less light) and a 17-fold increase in carotenoids in the back of the hand (exposed to more light).

Upping your carotenoid intake is not an excuse to skip the sunscreen, but it can help confer an extra degree of full-body protection.³⁸ You can supplement with carotenoids, but they are also abundant in red, yellow, orange and green fruits and vegetables.

• Astaxanthin

Astaxanthin is another carotenoid with skin-supporting action.

This red pigment gives salmon and lobster their colour—it has a potent antioxidant effect when consumed. Randomised, double-blind, placebo-controlled trials have shown that supplementation with 4–12mg astaxanthin daily can reduce signs of ageing such as fine lines and wrinkles.^39,40

Emerging evidence also suggests that astaxanthin can block the 5-alpha-reductase enzyme, which means it may help address androgen-dependent cases of acne too.⁴¹

• MSM

Methylsulfonylmethane (MSM) is an organosulphur compound that naturally occurs in some green vegetables, including alfalfa, cabbage and Swiss chard, and other foods such as dairy and chicken. It has long been popular as a joint supplement, but newer research suggests it can also have an impressive effect on skin health.

One pilot trial showed that ingestion of 1–3g MSM daily for 16 weeks reduced signs of ageing such as facial wrinkles and skin roughness.⁴² Mechanisms for its action are still being explored, but it is likely due to its ability to support collagen production and restore levels of the key antioxidant enzyme, glutathione.⁴³

• Probiotics

With the recent explosion of research into the gut-skin axis, we now know that gut dysbiosis is associated with a range of skin conditions, including acne,⁴⁴ atopic dermatitis, psoriasis,⁴⁶ and rosacea.⁴⁷

While specific probiotic strains have been shown to have specific effects on these conditions, there is also a role for a broad-spectrum probiotic in supporting general skin health.⁴⁸ Various

Lactobacillus and Bifidobacteria strains can reduce inflammation,⁴⁹ alleviate oxidative stress,⁵⁰ and improve skin barrier recovery⁵¹—all of which positively impact your complexion.

Considering these actions, it is not surprising to learn that probiotics have also been found to have an anti-ageing effect. One randomised, double-blind, placebo-controlled trial showed that 41 to 59–year-olds who took Lactobacillus plantarum HY7714 had shallower wrinkles after 12 weeks compared to those taking placebo.⁵²

Lifestyle considerations for healthy skin

Nutrition is a critical aspect of your skin’s exposome—but it is not the only one.53 For skin health, it is also important to consider:

Sun exposure. Increased signs of ageing have been linked to sun exposure in both Caucasian and Chinese populations.^54,55 Practise sensible sun exposure and use sunscreen when necessary.

Smoking. Smoker’s skin has altered hue, radiance, and more prominent facial wrinkling.⁵⁶ If you smoke, get the help you need to stop.

Pollution. A large epidemiological study of Caucasian women showed that exposure to traffic- related particulate matter contributes to skin ageing.⁵⁴ Pollution refers to the contamination of both indoor and outdoor environments by any chemical, physical or biological agent—so reduce your toxic load where possible.

Sleep. An experimental study found that restricted sleep led to hanging eyelids, dark circles under the eyes, more wrinkles and fine lines and droopy corners of the mouth.⁵⁷ For the sake of your skin, prioritise your sleep.

Stress. Chronic stress can exacerbate most skin conditions because it affects your skin’s ability to repair itself.⁵⁸ We cannot eliminate stress from our lives—but we can learn relaxation techniques that improve our response to stressful situations. Find out what works for you.

Skincare. Cosmetic products can disrupt the skin’s natural pH and negatively affect the skin’s microflora.^59,60 Treat your skin gently by choosing pH-balanced products and slimming down your skincare routine.

Looking after your skin is both a science and an art. As Dr James Lind discovered, you do not need to identify nutrients to realise that food has an effect—but adopting a pattern of eating that promotes nutrient-rich foods will serve your skin now and in years to come.

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About the author

Fiona Lawson
Nutritionist, researcher and skin specialist
BA (Hons), MSc, DipCNM, mBANT, AFMCP

Fiona Lawson is a former national magazine editor turned registered nutritionist. She holds an MSc in Nutritional Medicine and a BANT-registered post-graduate qualification in Nutritional Therapy. Fiona specialises in skin health, working with brands and individuals in her private nutrition consultancy. She is also the author of the acclaimed book, The Happy Skin Solution.

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If you have questions regarding the topics that have been raised, or any other health matters, please do contact our team of Nutritional Therapists.

nutrition@cytoplan.co.uk
01684 310099

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Last updated on 10th November 2022 by cytoffice