Within an increasingly ageing population, methods used to prevent premature, functional, and aesthetic decline are becoming of increasing interest. Factors, such as, diet, lifestyle, environment, and physiological stress can impact the rate our tissues age biologically. As other internal tissues suffer the consequences of ageing, the skins appearance reflects this externally; communicating to the outside world the extent age has impacted overall health. As patients begin to witness skin ageing, they may seek anti-ageing methods that benefit whole systems, owing to this demand, research has begun to dig deeper into more integrative, and less risky, methods of preserving health and youthful beauty. In Part I, of this two-part series, the author discussed how the rate of skin ageing can be directly modulated by the supplementation of key nutrients and, therefore, help preserve its healthy attractiveness. In Part II, this article will discuss more sophisticated explorations of optimal skin nutrition, including how whole food combinations, the synergy of phytonutrients, strategic use of probiotics, and phytoestrogens components can support the preservation of skin health. Finally, this article discusses some of the most recent reports regarding key diet modifications when attempting to re-enforce skin resilience to ageing; climate, patient demographics, and collagen sensitising factors are also discussed.
According to Lui1, antioxidant activity from fruits and vegetables have been linked to many health benefits, including cancer prevention and functional decline associated with ageing. Analysis of certain fruits and vegetables have shown that most of the antioxidant activity comes from complex mixture of phytochemicals within them and that their health benefits are attributed to these nutrients. Phytochemical extracts from plants, fruits, and vegetables show strong antiproliferative and anticarcinogenic properties that may be beneficial for health and the skin.
Polyphenols are phytochemical antioxidants, which have shown benefit in preventing diseases associated with oxidative stress2. Polyphenols are one of the most abundant antioxidants in the human diet, they are present not only in whole fruits and vegetables, but sources such as olive oil, chocolate, coffee, tea, wine, and some cereals. Polyphenols can be divided into phenolic acids, flavonoids, stilbenes and lignans. Flavonoids have been extensively studied and have shown antioxidative, anti-inflammatory, cytoprotective, and photoprotective benefits. Flavoids can further be categorised as flavone, flavonol, flavanone, and anthocyanins. These antioxidants have been studied and proven to have anti‑inflammatory, antimutagenic, and free radical scavenger activities. Furthermore, polyphenols have been shown to be beneficial in wound healing, protecting capillaries, improving circulation, and protecting dermal collagen from degradation and crosslinking3. These benefits seem to be dose-dependent with both topical and oral supplementation1. Some of the best-studied polyphenols are discussed below and include those extracted from green tea, tree barks, grapes, and berry sources.
Green tea polyphenols (GTP) in vitro have shown the ability to decrease hyperplastic response, oedema, epidermal antioxidant depletion, and contact hypersensitivity4–5. Due to its properties, GTP may prevent cellular behaviour associated with skin ageing and skin cancer4. The topical application of Epigallocatechin gallate (EGCG), the most significant phytochemical of green tea, has also been specifically studied and shown to decrease ultraviolet-B (UVB)-induced inflammation, UV oedema, erythema, and antioxidant depletion in epidermis of mice6. In 2013, Gianeti et al7 published a human study describing the benefits of green tea extracts beyond its antioxidative properties. This study showed that single daily applications can result in improved hydration, skin roughness, and appearance.
Resveratrol is another well-studied stilbene polyphenolic compound6. This natural polyphenol is found in grapes, peanuts, and berries and has shown strong antioxidant potential8. Resveratrol acts as a chelating agent and a radical scavenger. Additionally, resveratrol also displays strong anti-inflammatory properties. When taken orally, resveratrol exhibits cardiovascular benefits, improved cellular longevity, and a dose-related cell proliferation and collagenases inhibition, favouring fibroblast activity and overall skin health6. In studies, dietary bioactive supplementation of resveratrol and oligomeric proanthocyanidins (OPCs), have been shown to reduce skin wrinkling, and reduce systemic and skin oxidative stress9. Additionally, resveratrol has phytoestrogen properties, protecting female endocrine decline from age-related collagen loss8.
Anthocyanins are a group of flavonoids that are known for their capacity to prevent diseases owing to their antioxidant capabilities10. Anthocyanins have been found to be beneficial to dermal integrity due to their antioxidative, UV-protective, and anti-inflammatory activities in skin. Oral supplementation of grape seed extract, rich in pro-anthocyanidins, has additionally shown to decrease solar-induced hyperpigmentation in women with melasma2. Flavonoids too have exhibited strong potential for the prevention of skin ageing and Schagen et al6 studied and identified silymarin, apigenin, and genistein as having benefits for skin. These can be naturally found in the bark of trees, such as pear, apple, and cherry varieties.
Polyphenol-rich plant extracts have been shown to decrease oxidative damage of UV irradiation in skin cancer cell proliferation10. An example of how poly-phenolic compounds may work to benefit skin ageing can be seen in a 2009 Korean study on edible bog blueberry (ATH-BBe); Vaccinium uliginosum) juice. This ATH-BBB was able to inhibit the accumulation of intracellular reactive oxygen species (ROS) in fibroblasts damaged by oxidative UVB induced stress in vitro. ATH-BBe attenuated inhibition of procollagen levels normally induced during UVB. Additionally, ATH-BBe suppressed the secretion of all three metalloproteinases (MMP) enzymes secreted in normal response to UVB irradiation. ATH-BBe attenuated these extracellular matrix (ECB) depleting enzymes in a dose-dependent way. ATH-BBe has also been shown to inhibit cytokine secretion in response to UVB exposed dermal fibroblast, showing anti-inflammatory effects10.
Supplements combining the benefits of various polyphenols have become of increasing interest to academics. Patients using high doses of a supplement of flavonols from green tea and cocoa (epicatechin/catechin) have shown endogenous photoprotective benefits2 as well as improved skin health and appearance. The women in this study displayed improved cutaneous blood flow, skin density, and hydration parameters. Topical use of plant extracts rich in the polyphenolic compounds including catechin, epicatechin, caffeic acid, ferulic acid, and procyanidins has shown strong potential in preventing UV-induced damage and hyperpigmentation.
Additional studies have looked into preventing signs of skin ageing by using supplements that combine the benefits of vitamins, minerals and various polyphenols3. Results from this study showed that after 12 weeks of such a mix of nutrients, patients had a 21% improvement in skin textures and fine lines.
Phytohormones are plant products that have oestrogen-like effects and are thus referred to as phytoestrogens11. Isoflavones, a subtype of phytoestrogens, are found in soy, beans, lentils, and red clover. According to Sator, genistein and daidecin are the most important isoflavones. Isoflavones, have shown promise in producing estrogenic effects. These phytoestrogens have shown ability to protect against UVB induced skin damage, improve immunity, display estrogenic effects in post-menopausal women, increase skin thickness, promote collagen synthesis, and display antioxidant activity in animals and in vitro5. The high phytoestrogen content of Asian diets is thought to explain why women do not suffer from symptoms of degenerative skin changes in these regions11. Sator’s studies have shown topical application of phytoestrogens can produce the proliferation of epidermis, support collagen synthesis, and reduce the impact of enzymatic degradation of collagen.
In a study reported by Humbert et al12, regular consumption of fermented dairy products can improve natural skin barrier function by decreasing transepidermal water loss and improve cosmetic appearance. Probiotics improve gut barrier function and, consequently, the immune system, and antagonise inflammatory alterations manifested in skin as atopic dermatitis12. Moreover, probiotics protect the cutaneous immune system function altered by solar simulated UV exposure6.
Optimising skin benefits with bimodal supplementation
A combination of systemic and topical supplementation of nutrients can work together to enhance health-producing efficacy5. It has been concluded that best practice includes combining a number of antioxidants at dosages close to their recommended dietary allowance (RDAs) in order to prevent pro-oxidative activity. Additionally, this method of supplementation exceeds any individual supplement’s antioxidative activity8. Systemic consumption of antioxidants has been proven to increase concentration on the skin surface14. Increasing the amount of antioxidants in the skin has shown to be an efficient anti-ageing strategy, decreasing skin roughness and appearance of wrinkles. Because topical antioxidants do not reach the deeper skin layers, systemic incorporation may be a better modality to protect deeper skin layers from functional and structural decline14. This said, topical application allows enhanced protection from extrinsic insults, further protecting skin appearance and possibly improving health by better preserving its endocrine and immune function14. Synergetic interplay with several antioxidants could be promising for the future of skin health preservation6.
Diet can play an important role in preventing disease, increasing life quality, and as seen above, improving skin function and appearance13. The role of diet may be proportional to its specific dietary elements, i.e., vitamins, antioxidants, and phytochemicals13.
Dietary philosophies that have shown to improve overall health usually include calorie and protein restriction, high fibre, low-fat, and vegetable-based eating. These methods have been shown by Marin et al15 to introduce benefits via decreasing oxidative stress, inhibiting inflammatory processes, promoting telomere length, and decreasing incidence of disease. Conversely, eating diets high in saturated fats and carbohydrates can accelerate ageing by inducing oxidative stress and resulting telomere attrition. Epidemiological studies have shown that the consumption of fruit and vegetables is positively correlated with low incidence of melanoma16. Another study showed that across the Italian population, eating green leafy vegetables three times a week or more decreased skin cancer incidence16.
In terms of specific skin ageing, diet has also shown to be beneficial17. In a study of over 4000 women, aged skin was recognised as ‘wrinkled appearance’ and correlated with signs of senile dryness and skin atrophy. When compared to the women without visibly wrinkled skin, those without wrinkled skin had lower intakes of protein and total dietary cholesterol, and higher intakes of phosphorus, potassium, vitamin A, and vitamin C. It was noted that senile dry skin correlated with lower intake of linoleic acid and vitamin C17. Additionally, women with marked skin atrophy had lower linoleic acid than those without skin atrophy. Sufficient dietary vitamin C intake alone was associated with 11% reduction in the odds of a wrinkled appearance and 7% reduction of senile dryness. A unit increase of linoleic acid on a log scale was associated with respective reductions of 25% and 22% in the odds of senile dryness and skin atrophy. A 17g increase in dietary fat and 50g increase in carbohydrates increased the risk of wrinkled appearance and skin atrophy. It can then be gathered that diets rich in vitamin C and linoleic acid and low in fat and carbohydrates, may decrease the risk of the signs of skin ageing (wrinkle appearance, senile dryness, skin atrophy17. Independent of age, lifestyle, body mass index (BMI), supplement use, or education, diets higher in vitamin C correlated with a lower incidence of wrinkled appearance and senile dryness17. Interestingly, supplement use was not associated with reducing the risks of skin ageing. An increased intake of vitamin C via diet was shown to help dryness and appearance but supplement source did not have the same impact.
A 2011 study, showed that diet may impact the degree of actinic damage inflicted on UV exposed skin12. Similarly, it was shown that those with diets high in vitamin C, retinol, and minerals also benefited as they suffered less from UV-induced ageing. Those individuals that consumed foods, such as dairy, butter, margarine, and sugar products, suffered from higher degrees of actinic damage12. Purba et al18 conducted another study, analysing the effects of diet on photo-related ageing. In this study, Purba and colleagues analysed diet among Caucasians of Swedish, Greek, and Anglo-Celtic ancestry living in Australia, analysing correlations between food groups and skin wrinkling. Across groups, those that consumed high intakes of vegetables, olive oil, unsaturated fats, and legumes and with low intakes of milk, sugar, butter, and margarine, suffered the least amount of skin wrinkling in sun-exposed areas. The authors proposed that the foods’ protective benefits were derived from high antioxidant content (vitamins A, C, E, lycopene), phytochemical content (fruit and vegetable derived antioxidants and phytoestrogens), and those nutrients promoting oxidative resistance, anti-inflammatory, and fat-soluble vitamin absorption benefits (olive oil, fish oil). Furthermore, the study found that skin-wrinkling incidence was positively correlated with increased intake of meat, full-fat dairy, cakes and pastries, while negatively correlated with intake of legumes, fish and fermented milk18.
In another study, green leafy vegetables and egg consumption have been correlated with lower incidence of skin wrinkling16. Furthermore, this study showed green leafy vegetable consumption to negatively correlate with skin cancer risk. Green leafy vegetables are sources of β-carotene, lutein, and numerous phytonutrients16. Eggs may provide benefits via protein, lutein, and essential fatty acid content.
Vranešić-Bender13 also reported that intakes of fruit and vegetables, tea, wine, coffee, dark chocolate, may substitute supplements of antioxidants in the hope of reducing ROS damage and potentially improving health and rate of ageing. Another study showed that 6 weeks of consuming a flavonol rich beverage protected subjects’ skin from UV-induced damage16. This same study found that after 6 weeks of consuming this flavonol beverage, skin was found to be denser, with improved hydration and skin texture.
Other dietary considerations
In addition to considering what to eat for healthy skin ageing, some new studies are now more interested in what not to eat. Calorie restriction (CR), without malnutrition, has been shown to limit the rate of free radical formation in the mitochondria6. In humans, CR is thought to beneficially alter:
- Hormone metabolism
- Hormone-related signalling
- Oxidation status
- DNA repair
- Dysfunctional inflammatory processes
- Oncogene expression4.
With CR, histomorphological changes resulting from intrinsic ageing processes were delayed or prevented. Improved collagen and elastic fibre values, fibroblast activity, and capillary strength have been noted in response to CR induction. Additionally, CR has shown to alter the expression of certain metabolic and biosynthetic genes to retard stress responses associated with ageing in animals4. Calorie restriction is thought to induce these methods by activating sirtuin enzymes and positively affect transcription factors, which are vital to the healthy dealings of stress19. Activating sirtuins has shown to improve ageing in various ways, including improving gluconeogenesis, lipid metabolism, and mitochondrial function8.
Additionally, avoiding high sugar diets and dietary Advanced Glycation End Products (AGEs) (ingested with those foods prepared at high temperatures without the presence of water) can protect the collagen, lipids, and proteins vital to skin health20,21. The higher the sugar in the diet, the higher concentrations of sugar found in the blood and skin20. Furthermore, according to Gkogkolou & Bohm21, dietary AGEs are directly correlated with serum levels of AGEs, as well as inflammatory markers in humans. AGEs are found in high amounts in diabetics and could explain premature skin ageing in this group19. In vitro, the presence of AGEs in human skin correlated with signs of skin ageing and include:
- A decrease in proliferation and enhanced apoptosis of dermal fibroblasts
- An increase in the expression of pro‑inflammatory mediators in keratinocytes
- A decrease in collagen and extracellular matrix (ECM) protein synthesis
- An inhibition of growth factors and proteins significant for cellular function
- A decrease in the viability of keratinocytes and fibroblast after UVA exposure21.
Moreover, dietary AGEs interact with cellular and extracellular components resulting in cross-linking proteins, inflammation, and contribute to intracellular oxidative stress20. The accumulation of AGE in the skin, ultimately contributes to ageing of the tissues and skin. Since oxidation is involved in the formation of many AGEs, antioxidants may have protective benefits against their formation21. In vitro, ascorbic acid, alpha- tocopherol, niacinamide, pyridocal, sodium selenite, selenium yeast, trolox, riboflavin, zinc and manganese have shown anti-glycation properties. Green tea, vitamins C and E, and a combination of N-aceylcystein with taurine and oxerutin showed promise of protecting collagen glycation in mice. In vitro, flavonoids, such as EGCG showed benefit in antagonising AGE induced inflammation. In human subjects, vitamin C and blueberry extract proved beneficial in reducing serum protein glycation and skin benefits21. Including certain spices in diet may help inhibit the formation of AGEs21. Cinnamon, cloves, oregano, allspice, ginger, and garlic have shown benefits in animals. No human study to date has shown a decrease in cutaneous AGEs via nutraceuticals21. CR may be effective in preventing AGE-accumulation in the body although dietary restrictions are not pragmatic practice in humans21. Most recently, resveratrol supplementation has been discussed to have ‘CR-like’ beneficial effects on sirtuin enzymes and, therefore, offer a more clinically applicable method of preventing glycation-associated health and skin effects19.
Special nutritional attention
Nutrients from food may be insufficient in cases of stress, adolescents, athletes, elderly, extreme weather (sun or cold/dry conditions), and in situations where one would want to promote healing12. Without attention to certain micronutrients, accelerated skin ageing may be noted12. As pro-oxidative toxicity is possible with systemic antioxidants, it is important to look for safe sources from food and complementary topical administration that has not shown harmful effects14. Since UV radiation imposes an important risk to accelerated skin ageing, the seasonal nutritional demands of the skin have been specifically studied. Some conclusions have been drawn regarding the special nutritional role of certain protective supplements and foods in limiting environmental extrinsic stress and associated ageing.
Carotenoids, essential fatty acids, probiotics, vitamin C, and vitamin E have all been studied and reported as beneficial for reducing the negative skin effects of UV radiation. Similarly, specific studies have shown that eating foods rich in carotenoids, tocopherols, vitamin C, and omega-3 fatty acids for 90 days before sun exposure could provide protection from harmful UV-induced signalling cascades and the oxidative effects associated with premature ageing and skin cancer12. Additionally, a study by Kopcke and Krutmann22 showed protective properties of β-carotenoid supplementation when used 10 weeks prior to sun exposure12. Another study suggested an alternative nutritional mechanism for protecting skin from UV damage. This study showed that a diet high in flavonoids (green tea, apples, and oranges), over a shorter time frame of 11 days, proved effective in providing anti-UVA benefits12. Since UV radiation is a major contributor to extrinsic ageing, proper supplementation of these nutrients could help preserve the skin’s youthful function and appearance.
Nutritional strategies have shown promise in terms of preventing skin ageing. Studies have shown correlations between healthy eating patterns and improved skin ageing and related these correlations to their impact on oxidative stress, inflammatory cutaneous cascades, glycation and possibly telomere length. Incorporating key wholefoods may be the safest way to promote whole body health and provide a multitude of key nutrients for optimal skin ageing. Wholefoods are an advantageous way to provide nutritional support; the risk of toxicity via food is unlikely and the tissues can benefit from both synergistic and complementary action of the variety of nutrients provided.
Nutraceuticals, both oral and topical, have proved to be beneficial to certain individuals’ abilities to resist extrinsic ageing and maintain a youthful appearance. In some cases, a visual sign of ageing might suggest nutritional deficiency (see vitamin C and oligoelements) while in other cases, certain risk factors may call for extra nutritional attention (see vitamin D and phytoestrogens). Seasonal climate extremes may be another occasion where advanced nutritional support may reduce skin ageing. In addition to traditional photoprotection guidelines (sunscreen and sun avoidance during peak times), it may be beneficial to discuss the benefits of a diet high in vitamins A, C, E and flavonoids with patients in order to prepare them for high UV seasons. For those with fragile skin, times of high sunshine may also call for additional nutritional support from an omega-3 fatty acid supplement and, possibly, a probiotic.
In general, vitamins C and E, essential fatty acids, and phytonutrients seem to have the most global value across sub-categories and populations. Despite mounting research supporting the benefits of supplementation, the challenge still lies in identifying which supplements provide quality ingredients, with safe, and effective physiological benefits. In ageing populations, vitamin D and CoQ10 supplementation may carry more importance for healthy skin ageing, as well as phytoestrogens for those women in menopause. Owing to vitamin D’s importance for health and skin ageing, supplementation may be considered appropriate to those ageing or at-risk individuals. Additionally, for those metabolically-challenged, attention to protein and oligoelements may need to be evaluated.
Certain diets may favour healthy skin ageing while others may accelerate it. Studies have shown eating diets low in fat and carbohydrates may favour better skin ageing. Additionally, as the evidence mounts of glycation’s impact on skin ageing and health, it may be best to avoid the formation, accumulation, and intake of AGEs. Avoiding AGEs means avoiding foods cooked at high temperatures and high on the sugar index.
Lastly, preventing skin ageing by means of CR has been postulated. More human studies are needed to understand how this may be used as a valuable method of anti-ageing. Certain nutrients have shown potential in simulating CR effects without the need for radical lifestyle modification. More studies are necessary to explore this field of research.