It has taken some time for food ingredients used for functional foods and supplements to enter the beauty sector. Anja Dahten & Joerg Gruenwald investigate the ingredients with potential to grow this market
There is increased awareness of the link between nutrition, health and physical appearance and the market for beauty supplements and beauty foods is growing. At the same time, consumers are increasingly demanding high quality products and scientifically substantiated efficacy. So-called nutricosmetics promise skin related health benefits via systemic action in the form of supplements, drinks and dairy products. The idea is not new, but new data supports the idea that dietary bioactives – such as vitamins, minerals and secondary plant ingredients, especially carotenoids and polyphenols – have beneficial effects on skin health and integrity.
Oral ingestion of bioactive ingredients has benefits over topical application in potentially metabolising and presenting substances in their active forms to the entire tissue. Furthermore, blood will continuously replenish the skin’s epidermis, dermis, subcutaneous fat and sebum. Topically applied ingredients often show low stability and penetration properties, but remember that substances have to pass the gastrointestinal tract and the intestinal barrier to reach the blood circulation, which could be a limiting factor for the efficacy of bioactive compounds taken orally.
The efficacy of a product ingredient complex is also affected by the fat and water soluble properties of several compounds. Moreover, some nutrients may indirectly affect skin properties via a secondary messenger pathway. For instance minerals and their derivates (eg zinc, copper) promote enzymatic scavengers, such as superoxide dismutase, catalases and peroxidases and provide a greater range of skin damage protection compared to a single compound. In contrast, beta-carotene, vitamins C and E have been shown to directly neutralize free radicals. We have to recognise that aside from analysing the particular ingredients used, at least the final formulation and mixture must be tested for real product efficacy. Claims are often based only on the individual ingredient data and/or only traditional use. Furthermore, in vitro data can provide the first indication of ingredient actions, but only placebo controlled clinical trials are able to substantiate a proposed health benefit.
ANTI-AGEING
Our skin is constantly exposed to pro-oxidant environmental stress resulting from air pollution, UV radiation, chemicals, microorganisms and ozone. In addition, unhealthy lifestyles (diet, alcohol, smoking) contribute to the assault on skin health and well-being. If the endogenous antioxidant defences decrease, oxidation of skin cell lipids, proteins and DNA structures may occur more rapidly. As consumers are more open to the idea of eating beauty the natural way, the purpose of beauty foods and supplements is to slow down the process of premature ageing via effective botanical ingredients based on their antioxidative properties.
Carotenoids – such as beta-carotene, lycopene, luteine or zeaxanthine – have been shown to be effective quenchers of reactive oxygen species (ROS), 80-90% of which are responsible for oxidative skin damage and typical signs of ageing, such as pigmentation, dryness, wrinkles and loss of elasticity. Studies have shown that dietary carotenoids measurably accumulate in skin after ingestion, without reaching a plateau over 12 weeks. High concentrations were measurable on the forehead and the palm of the hand. New spectroscopic data from the Dermatological Department at the Charité-University, Berlin indicates that a higher level of antioxidants in the skin (eg lycopene) are correlated with measurable and visible lower levels of skin roughness. New studies point to the fact that the antioxidant potential of the skin could be increased by the use of miscellaneous antioxidants, preferably in a combination of topical and ingestible formulations.
Vegetable oil, nuts, turnip greens and certain fruits (eg mango) are notable sources of the fat soluble vitamin E (tocopherol); of these isoforms, alpha-tocopherol is the most potent antioxidant. Skin vitamin E exhibits a gradient of concentration, with higher levels in the dermis compared to stratum corneum and several times greater levels in facial skin than in the skin of the upper arms. Vitamin E is used in topical and orally applied cosmetics to conservate fats/oils and fat-soluble antioxidants, such as beta-carotene and vitamin A. Furthermore, oral beta-carotene supplementation, in combination with vitamin E, significantly bolsters the skin’s antioxidant defences. But in vitro test applications of vitamin E also point to collagen stabilising effects.
LycoRed Ltd offers a natural tomato extract with lycopene, vitamin E and other secondary plant extracts with antioxidative potential. The product is claimed to provide year-round protection against free radical damage and is promoted to enhance beauty by increasing skin density, thickness and smoothness.
Vitamin C (ascorbic acid) is an effective antioxidant and essential cofactor in numerous enzymatic actions, and is claimed to protect skin against ageing by stimulating collagen formation. Mid-range ascorbate levels (30mg/kg BW) are detectable in human skin, but oral distribution in the epidermis and dermis has only been determined in animal models so far. It is known that the skin’s vitamin C pool can be selectively depleted; eg by UV radiation or in atopic dermatitis lesions. But man and primates have lost their ability to synthesise vitamin C by itself. While it has been thought that the skin is one of the most sensitive organs to vitamin C deficiency (scurvy), new data indicates that the skin can cope with marginal amounts in comparison to the brain and lungs. Indeed evidence of some beneficial effects exists, but data is lacking to substantiate these effects.
Plant extracts from green tea and mate, cocoa, berries, pomegranate, echinacea, grape seed or aloe vera have been widely used as topical applications for wound healing and anti-ageing treatments. These plants share one characteristic feature. They all produce flavonoid compounds with phenolic structures, highly potent for neutralizing free radicals. High quantities are found in certain fruits and tea. Polyphenols, such as catechins and anthocyanidins, have shown a variety of physiological effects in vitro, including antioxidative, immunomodulatory and anti-gentoxic effects.
Epigallocatechingallate (EGCGs) are the most abundant polyphenols in tea leaves and extracts. Mice consuming labelled EGCG show an equivalent radioactivity in the skin. Oral and topical application of brewed green tea, green tea extracts or green tea polyphenols (GTPPs) show significant protection against inflammation and UV or chemical induced carcinogenesis. In addition to skin protecting effects, oral green tea administration reduced dermal fatty tissue by increasing metabolic rate, which led green tea to being seen as a potential slimming ingredient. However, human studies are still controversial, presumably because human dermis provides a stronger barrier to vascular absorption and so murine data can’t be transferred to humans. This data gives useful indications of a nutrient with multifunctional potential in regard to antioxidant, UV protective and anti-inflammatory properties.
Pomegranate is also rich in polyphenol compounds, dominated by anthocyanins and tannins. Pomegranate extract has shown inhibitory effects on UV-induced skin pigmentation in a double blind, placebo-controlled clinical trial. A decrease in skin reddening and an increase in skin hydration has been shown after four weeks of supplementation with oligomeric proanthocyanidins (OPC) from grape seed extract. But it is often difficult to evaluate compound specific effects because a large number of antioxidants occur in plants and plant extracts and it is often the natural mixture that leads to the desired results.
Essential fatty acids, such as eicosapentaenoic acid (EPA) and docohexaenoic acid (DHA), are integral parts of all cell membranes, and are precursors of anti-inflammatory precursors. Essential omega-6 fatty acids, such as g-linolenic (GLA) acid, and omega-3 fatty acids, such as a-linolenic acid (ALA), and their metabolites can’t be metabolised de novo in humans and must be obtained from dietary sources. But our so-called western diet lacks sufficient ingestion of omega-3 fatty acids, which is correlated with skin related disorders, inflammation and allergy. In vitro DHA and EPA treatment has been shown to improve skin barrier function and collagen synthesis. However, trials of fatty acid supplementation have given inconsistent results so far and skin related clinical trials are necessary to prove the benefits of increased fatty acid ingestion.
Berries such as sea buckthorn, blackberries and blackcurrants are getting a lot of attention because they contain several polyphenols, carotenoids, vitamins (vitamins A, B, C and E) as well as essential fatty acids (omega 3, 6 and 9). A placebo controlled, parallel study has shown an increase of DHA in human skin after four months’ daily ingestion of 5g sea buckthorn seed oil.
Beauty supplements producer Oenobiol provides a line of supplements with well substantiated product claims. ‘Anti-age’ is claimed to significantly reduce imperfections on the skin’s surface. The main active ingredients are carotenoids (lycopene and lutein), vitamin E, omega-3 fatty acids and selenium. Its efficacy has been clinically and dermatologically tested in a mono-centric, placebo controlled, post-marketing study showing an 89% reduction in activity of free radicals after the first month of treatment. Imperfections in the skin surface are visibly reduced after three months of treatment. Observed parameters were skin density, skin thickness, skin surface (roughness) and serum concentration of antioxidants. Each observed parameter was improved in a statistically significant manner compared to placebo.
SUN PROTECTION
Because UV radiation is the main cause of the premature signs of skin ageing and skin cancer, sun protection is normal in anti-ageing and beauty products. As UV induced skin damage has been shown to be substantially caused by oxidative stress, it suggests the utility of antioxidants as dietary supplements as well as sunscreens. Carotenoids are the best researched bioactives offering measurable photoprotective benefits via absorption, reflection and/or scattering of visible and UV light. Clinical studies on the systemic use of beta-carotene have shown that a daily intake of 15-30mg over a period of about seven to 12 weeks increases protective skin properties against UV induced erythema and inflammation. A recent study of women aged 25-50 showed that a daily intake of 10mg lutein over a period of 12 weeks significantly increased skin hydration and elasticity. Carotenoids are often combined with antioxidative vitamins, such as vitamins C and E.
Ingredients supplier Cognis, known for innovative concepts for functional foods and dietary supplements, has used this knowledge to develop a useful formulation to boost skin elasticity and natural defence. ‘Holiday skin protection’ contains a useful antioxidant package including tocopherol (vitamin E) and carotenoids (beta-carotene, lutein and zeaxanthien). The benefit of such antioxidant complexes is in the ability to protect each other from autoxidation, increasing the antioxidant potential of the skin.
Nestlé and L’Oréal joint venture Innéov is a good example of a well substantiated product line. Innéov ‘sun’ for example offers complementary care for sun protection, combining a carotenoid complex and the patented natural extract Skin-Probiotic. The product is claimed to rapidly intensify the colour of a tan and to strengthen the skin, if taken daily four weeks before and during sun exposure. Product properties, such as a decrease in skin reddening, pigmentation and skin dryness after UV exposure, are reported to be verified in placebo controlled, double-blind, randomised clinical trials.
But while sun protection ingredients and supplements are often well substantiated, it is important to remember that they do not provide complete UV protection alone.
ANTI-CELLULITE
The claim of anti-cellulite properties is often included on skin care products, but can these products fulfil their promises? Cellulite is considered to be a hormone conditioned metabolic disorder causing alterations and structural changes in connective and subcutaneous adipose tissue. But the cause is still debated. Anti-cellulite creams can be sufficient to stimulate microcirculation and provide a smoothing skin feel, but to reach deeper skin layers, topical applications alone do not seem to be effective. Supplements use ingredients with slimming effects, such as green tea or caffeine. To improve lipolysis of adipose tissue, one of the most promising ingredients is conjugated linolenic acid (CLA) from safflower oil, such as Tonalin from Cognis. The ingredient’s ability to reduce body fat and lean body mass has been analysed in placebo controlled, double-blind randomised clinical trials (two to 12 weeks). Grape extract, known to limit fat absorption and accumulation by inhibition of lipase, could also be a useful ingredient for lypolysis.
Nivea is using CLA benefits in its Goodbye Cellulite capsules. The CLA is combined with mate leaf extract (EFLA 920) to boost thermogenesis and vitamin E to increase skin moisture. The capsules are to be used in combination with the gel-cream provided to modify the skin’s appearance. In an open clinical trial – including photo evaluation, expert scoring and volunteer self assessment – signs of cellulite were reported to be visibly reduced after four weeks of treatment.
BEAUTY FOODS
In addition to supplements, the launch of products from a beauty platform offers excellent perspectives for growth in the functional food sector. According to GNPD-Mintel over 600 new beauty food products were launched globally between 2004 and 2007 and these are predicted to grow at 10% a year. Products dominating the sector are non-alcoholic beverages (50%) – eg teas, fortified water and juices – followed by dairy products (18%) and confectionary (11%).
Asia has been the sector leader for a long time, but in Europe launches are now coming from the Netherlands, France and the UK. Among the most popular are the spoonable yoghurts – Beauty Case (Emmi) and Essensis (Danone) – claimed to nourish skin from the inside. According to Danone’s studies, eight out of ten women noted more beautiful skin after six weeks’ use of the product, which contains probiotics, green tea antioxidants, g-linolenic acids from borage and vitamin E. Beauty Case covers this claim with a formulation of aloe vera, green tea extract, milk serum, vitamins C and E, biotin and folic acid. The product is claimed to be particularly healthy for skin cells, leaving them hydrated, elastic and protected.
In Asia products tend to target skin care with ingredients such as aloe, collagen, co-enzyme Q10 and ceramides claiming to increase skin elasticity and whiten skin. The western market focuses more on anti-ageing and slimming benefits with plant derived antioxidants from fruits and herbs and vitamin fortification to smooth wrinkles and lines and rebuild collagen. More recently oral collagen application has been gaining interest on the global scene, primarily in dairy products, though there is as yet no proof that orally ingested collagen affects skin health and elasticity. However, it has been shown that daily ingestion of 10g collagen peptide affects properties of adult women’s skin, such as water absorption and hydration, and in animal studies an increased density of collagen fibrils has been observed. However, further investigation including clinical is required.
Origin as well as processing may influence the collagen-type action. For example, a new beverage from Nutrifood Indonesia contains collagen derived from cattle bones, which were certified as permissible by the Indonesian authorities, and Rousselot has come up with a new cocktail that includes a hydrolysed collagen similar to the skin’s type. But considering the side effects associated with increased sugar intake, the benefit of consuming collagen enriched marshmallows (Eiwa confectionary, Japan) or soft gummy candy (Meiji Seika Kaisha, Japan) is debatable.
Following two years of intensive research by Solbar, topical and orally applied soy isoflavones are the latest trend. Solbar reports clinical research showing that soy isoflavones help recover and reinforce skin elasticity and improve antioxidant activity. Furthermore, soy isoflavones have been shown to act synergistically with grape seed extract and lycopene, improving antioxidant activity and skin elasticity.
Cocoa is one of the richest sources of antioxidative flavanols, and the cocoa and chocolate market is predicted to show radical growth as a convenient oral delivery format for health and beauty. Because the ingestion of high flavanol cocoa has been shown to lead to an increase of skin density and hydration, modified manufacturing processes increasing the antioxidative potential of cocoa powder or extract make cocoa an even more valuble focus for skin health benefits.
There is encouraging scientific evidence for the effectiveness of several dietary bioactives in nutricosmetics, but the products often lack well controlled and skin related clinical trials. Because health and nutrient claims on foods, beverages and supplements have to be substantiated in accordance with the health claim directive (1924/2006), more proven scientific background on product usage is expected soon, improving the image of the nutricosmetics segment.
Since topical as well as orally applied dietary ingredients may improve the skin health by various mechanisms and to different degrees, the most efficient way to fully exploit the natural potential is to combine cosmetic and nutricosmetic benefits. In this way dietary supplements as well as functional foods seem to be useful substitutes or additions to currently available topicals. However, functional foods and supplements support but will never be a substitute for a healthy, active lifestyle with a diet high in fruits and vegetables.