Getting to Know Your Skin
Did you know that the skin is the largest organ in the body and it comprises about 15% of our bodyweight! Indeed, the total skin surface of an adult ranges from 12 to 20 square feet. That’s a lot of skin! The skin is composed of about 70% water, 25% protein and 2% lipids with 3 main layers that include the epidermis, dermis and subcutaneous tissue.
The epidermis is the top most layer of the skin. It has no blood supply, but it is nourished by the blood vessels in the dermis. The thickness of the epidermis is usually 0.5-1mm, but this is dependant upon where about on the body we are looking. For example, we have thicker skin on soles of our feet and palms of hands.
The dermis is the middle layer of the skin and it is the thickest of the skin layers comprising of a tight, sturdy mesh of collagen & elastin fibres. These fibres are important proteins, as collagen is responsible for structural support and elastin for the resilience of the skin. The dermis is the layer responsible for the skin's structural integrity, elasticity and resilience. Wrinkles arise and develop in the dermis.
Subcutaneous tissue is the innermost layer of the skin located under the dermis consisting of connective tissue and fat molecules. Subcutaneous fat acts as a shock absorber and heat insulator protecting underlying tissues from cold and mechanical trauma. The loss of subcutaneous tissue, which is typically associated with ageing, leads to wrinkles and sagging of the skin.
Functions of the Skin
What is Skin Aging?
Skin aging is a complex process that is determined by both internal and external factors which results in a progressive loss of structure and function. The changes that occur in the skin over time are much more related to the interaction of the skin with the environment than to genetic predisposition. Therefore, in humans, it can be said that skin aging is related to personal lifestyle as well as the chronological clock.
Internal or intrinsic skin aging is driven by factors such as genetics and the natural consequence of physiological changes over time as well as oxidative stress. However, there is not much we can about our genetics so we need to focus on the factors that are within our control. Intrinsic aging is clinically characterised by loss of elasticity and fine wrinkles as well as skin atrophy and prominence of vasculature.
External or extrinsic skin aging is driven to a large extent by environmental factors and external stressors such as ultraviolet radiation (UVR), pollution and lifestyle factors which have been shown to stimulate the production of free radicals and generate oxidative stress. Extrinsically aged skin is characterised by deep wrinkles, rough texture, telengiectasia and irregular pigmentation. Telangiectasia is a condition in which tiny blood vessels called venules widen and cause threadlike red lines or patterns on the skin. These patterns, or telangiectases, form gradually and often in clusters. They're sometimes known as “spider veins” because of their fine and web like appearance. The severity of extrinsic aging depends on skin type, with the features being more prominent in type I or II skin and less noticeable in type III or higher skin. The following table shows the different skin types:
Table 1. The Fitzpatrick skin phototypes
Factors That Accelerate Skin Ageing
We know that skin aging is related to personal lifestyle. It is known, for example, that smoking or excessive exposure to solar radiation and low air humidity causes the appearance of wrinkles. In addition, poor diet and excess alcohol intake, as well as some diseases such as Type II Diabetes can significantly accelerate the premature ageing of the skin.
Throughout our lifetime, we accumulate damage generated by sun exposure or UV radiation. UV causes inflammation, immune changes, and DNA damage that promotes cellular ageing in our skin. Research shows that frequent episodes of serious sunburn can increase your risk of developing skin problems in later life, such as aging (wrinkling) and skin cancer.
DNA absorbs UV light, and the absorbed energy can result in damage to DNA – our genetic material. What happens is that excessive ultra violet radiation (UVR) exposure can break bonds in the DNA. Most of the DNA breakages are repaired by proteins present in the cell, but if the amount of damage is too great, the alterations to the DNA may remain as permanent mutations. The unrepaired genetic damage of the DNA can lead to skin cancers. Of course, we know that staying out in the sun too long gives us sunburn. This is an acute inflammatory reaction that follows excessive exposure of the skin to ultraviolet radiation. Inflammation and the resulting accumulation of reactive oxygen species (ROS) play an important role in skin aging.
UVR consists of both UVA and UVB radiation. It is UVB that is primarily responsible for producing sunburn but because the solar energy reaching the earth is primarily UVA, it also contributes to sunburn and other harmful effects of UV radiation. Most of us are exposed to large amounts of UVA throughout our lifetime. UVA rays account for up to 95 percent of the UV radiation reaching the Earth's surface. Although they are less intense than UVB, UVA rays are 30 to 50 times more prevalent. They are present with relatively equal intensity during all daylight hours throughout the year, and can penetrate clouds and glass.
UVA, which penetrates the skin more deeply than UVB, has long been known to play a major part in skin aging and wrinkling (photoaging), but until recently scientists believed it didn’t cause significant damage in areas of the epidermis (outermost skin layer) where most skin cancers occur. Studies over the past two decades, however, show that UVA does indeed damage skin cells in the basal layer of the epidermis, where most skin cancers occur.
There is extensive evidence indicating that oxidative stress induced by free radicals otherwise known as Reactive Oxygen Species (ROS) play an important role in the process of skin ageing.(1) In fact, the aging process in the skin is driven by ROS to an extent that is not attained in any other organ. Ultraviolet radiation, cigarette smoke exposure, environmental pollutants, and the natural process of ageing contribute to the generation of free radicals and ROS in the skin.
UVR plays a primary role in generating ROS in skin cells which leads to DNA damage as discussed previously.
Advanced Glycation End-Products (AGE’s)
In the recent years, the role of advanced glycation end products (AGEs) has been increasingly discussed in skin aging, and the potential of anti-AGE strategies has received high interest from pharmaceutical companies for the development of novel anti-ageing cosmeceutical compounds.
Advanced glycation end products (AGEs), also known as glycotoxins, are a diverse group of highly oxidant compounds. The formation of AGEs is a part of normal metabolism, but if excessively high levels of AGEs are reached in tissues and the circulation they can become pathogenic which essentially means they cause disease.
When glucose molecules and other sugars such as fructose attach themselves to proteins, it is called glycation. The binding of sugar to protein causes cross linking of proteins. Cross linked proteins cause more damage by reacting with free radicals and other toxins to create Advanced Glycation End products (AGEs). These AGEs bind to cells at special attachment sites called RAGEs (Receptor for AGEs) and this results in the production of several harmful chemicals damaging tissues. Unfortunately the process of glycation is what damages the surface of the skin by weakening collagen.
Collagen glycation impairs its function in various ways. Inter-molecular crosslinks of adjacent collagen fibres change its biomechanical properties leading to stiffness and a decrease in flexibility. Collagen glycation also makes it resistant to degradation which inhibits its removal and replacement by newly synthesized and functional collagen. As a result, tissue permeability and turnover is impaired. These AGE’s also affect elastin and fibronectin which contributes further to what is known as dermal dysfunction.
As we discussed earlier, AGE’s or glycotoxins are produced in the body, however, they also exist in foods. AGEs are naturally present in uncooked animal-derived foods, and cooking results in the formation of new AGEs within these foods. In particular, frying, roasting, grilling, searing and broiling propagate and accelerate new AGE formation.
The fact that the modern diet is a large source of AGEs is now well-documented. Because it had previously been assumed that dietary AGEs (dAGEs) are poorly absorbed, their potential role in human health and disease was largely ignored. However, recent studies clearly show that dietary AGEs are absorbed and contribute significantly to the body’s AGE pool. These dietary AGE’s are known to contribute to increased oxidant stress and inflammation, which, as we know, accelerates skin aging. They are also linked to the recent epidemics of diabetes and cardiovascular disease. Here is a table of foods with the highest level of AGE’s.
Table 2. Foods with High Levels of AGE's
How to Stop Premature Skin Aging
In these modern times, we are constantly bombarded with all manor of fancy potions with the next sparkly new ingredient that promise to keep us young forever. Sometimes this means that we forget about the basics which may seem a little boring, however, they are tried and tested and highly effective. In the next few sections, we'll take a look at some of the basics that we can implement quickly and easily.
Managing Sun Exposure
Even if you live in a very sunny place, we need to balance the health benefits of sun exposure with the risks of skin cancer. Over the years, the confusion about the ideal levels of sunlight has increased, with different advice being issued by various organisations. In 2010, a group of seven British health organisations issued a ‘consensus statement’ to provide some guidance on sun exposure and vitamin D. This brings together the latest evidence on vitamin D and provides some clarity on what has been a controversial issue. The consensus is that short and frequent spells in the summer sun, several times a week, can increase your vitamin D levels and benefit your health. More specifically, going outside in the sun for 10 to 15 minutes, several times a week, is optimum for increasing vitamin D levels and represents a safe balance between adequate vitamin D levels and any risk of skin cancer.
Our skin has several internal defense mechanisms against UVR. These include melanin and antioxidants. Melanin, the pigment deposited by melanocytes, is the first line of defense against DNA damage at the surface of the skin. It’ job is to scatter and absorb UVR but it cannot totally prevent skin damage.
UVR exposure causes DNA oxidation and the generation of Reactive Oxygen Species (ROS) or free radicals. When these free radicals exceed our capacity to combat them, we get oxidative stress. The reduction of oxidative stress can be achieved on two levels: by lowering exposure to UVR and/or by increasing levels of antioxidant defense in order to scavenge these free radicals. Antioxidants combat oxidative stress and attenuate the damaging effects of reactive oxygen species (ROS). They impair and even reverse many of the events that contribute to toxicity or disease in the skin.
However, chronic exposure to UVR can overwhelm the skin’s antioxidant capacity, leading to oxidative damage, premature skin aging and skin cancer. There are numerous antioxidants in the skin as follows:
Dietary antioxidants play a major role in maintaining the homeostasis of the oxidative balance and we get most of our antioxidants through diet, however, UVR exposure affects the skin antioxidants. Vitamin E, GSH, SOD, catalase, and ubiquinol are all depleted in both the dermis and epidermis layers of the skin when exposed to UVR. Research shows that the oxidation caused by UVR exposure can be prevented to a large degree by prior antioxidant treatment. There have been many studies performed with different antioxidants or combinations of antioxidants and phytochemicals that have found evidence that free radical damage can be prevented to a significant degree. Lets take a closer look.
Many studies have shown that it is possible to delay skin aging and to improve skin conditions through diet and certain nutritional supplements. Nutritional antioxidants act through different mechanisms and in different compartments, but are mainly free radical scavengers.
Since oxidation steps are crucially involved in formation of many AGEs, substances with antioxidative or metal chelating properties, may also have anti-glycating activities. As a result, there is a lot of interest directed towards nutrients and supplements or so called “nutriceuticals,” as natural tools against AGEs and skin ageing. Previously, we discussed that some foods are high in AGE’s and that high temperature cooking methods can increase the AGE content in a food. In contrast, Table 3 below shows foods that have significantly less AGE’s.
Table 3. Foods with Lower Levels of AGE's
It is interesting to note that when chicken is steamed or cooked with lemon, how the AGE is content is much lower. We’ll talk more about cooking methods later in this article.
Eating more fruit and vegetables is a good way to reduce AGE consumption. Dietary phytonutrients, which are found in the pigments of various colourful fruits and vegetables are responsible for this. One type of phytonutrient in particular, called iridoids, which are found in deeply coloured blueberries and cranberries, can lower AGEs in the body.
As we’ve seen previously, free radicals cause damage in the skin at a cellular level. Our natural defences for these free radicals are antioxidants, however, when the free radicals outnumber the antioxidants, they take over and start to cause havoc. That is why it is important to keep our antioxidant levels topped up. Lets take a closer look some of the antioxidants that can help to prevent skin aging.
Vitamin C, also named L-ascorbic acid, is water soluble, photosensitive and is not naturally synthesized by the human body. Therefore, adequate dietary intake of vitamin C is required and essential for a healthy human diet. Vitamin C can be used orally and topically for skin benefits as it helps to stablise the structure of collagen.(2,3) It also plays a role in cholesterol synthesis, iron absorption and increases the bioavailability of selenium.
Vitamin C deficiency can result in impaired collagen synthesis and is also known for causing scurvy, a disease with some manifestations such as fragility, skin lesions, gum bleeding, ease of developing bruises or slow wound healing. Fresh fruits and vegetables such as citrus fruits, blackcurrant, rose hip, guava, chili pepper or parsley are rich in vitamin C.
The vitamin E complex is another important group of antioxidants consisting of a group of 8 compounds called tocopherols. These are potent antioxidants that scavenge free radicals and work synergistically with Vitamin C. Higher amounts of tocopherols are found in vegetables, vegetable oils like wheat germ oil, sunflower oil, safflower oil and seeds, corn, soy and some sorts of meat. The intake of natural vitamin E products helps against collagen cross linking and lipid peroxidation, which are both linked to aging of the skin. However, we need to be careful with the consumption of oils that are high in Omega 6 such as sunflower oil as this can tip the balance of the Omega 3/Omega 6 ratio. Too much Omega 6 is inflammatory and we are ideally looking for a ratio of 2:1 Omega 3 to Omega 6. However, in the US, this ratio is the other way round with Omega 6 consumption far greater than Omega 3 at up to 20:1. This is a highly inflammatory level.
Carotenoids are organic pigments that are produced by plants and algae, as well as several bacteria and fungi. These include beta-carotene, astaxanthin, lycopene and retinol, which are all highly effective antioxidants and have been documented to possess photo-protective properties.
Beta-carotene is the most prominent member of the group of carotenoids. Compared with other carotenoids, the primary role of beta-carotene is its provitamin-A activity but it also a potent antioxidant that combats free radicals. Carrots, pumpkin, sweet potatoes, mangos and papaya are rich sources of beta-carotene.
Supplementation with beta-carotene can enrich the skin and help protect against photo-ageing from UVR and numerous studies show that it is effective in helping to prevent sunburn.(4) In these studies, the supplementation lasted for 7 weeks, with doses greater than 12 mg/d. Treatment periods of only 3–4 weeks, studies reported no protective effect.
Asta what? How do you pronounce that I hear you say! Asta-Zan-Thin is a naturally occurring carotenoid or pigment found primarily in marine organisms such as salmon, krill, shrimp as well as micro-algae. This carotenoid is the pigment that gives salmon their pink color.
Astaxanthin is a very potent anti-oxidant and anti-inflammatory. In fact, it is the strongest antioxidant known and has many other health benefits for the eyes, central nervous system, brain, skin, immune system, exercise capacity and recovery ability. Studies have shown that Astaxanthin showed a significant photo-protective effect and counteracted UVA-induced alterations significantly. The uptake of astaxanthin by fibroblasts was higher than that of beta-carotene, which leads to the assumption that the effect of astaxanthin on photo-oxidative changes was stronger than that of the other carotenoids. A study showed that astaxanthin could interfere with UVA-induced matrix-metalloproteinase-1 and skin fibroblast elastase expression. Indeed, there are numerous studies showing that topical or oral administration of Astaxanthin can prevent or at least minimise the effects of UVA radiation, such as skin sagging or wrinkling.(5-9)
This is a polyphenol found in numerous plant species including grapes, peanuts, fruits, red wine, and mulberries. Studies have shown resveratrol to possess the ability to protect the skin from harmful UV-induced effects because of it’s potent antioxidant, anti-inflammatory, and anti-carcinogenic properties.
The biggest challenge that resveratrol researchers are currently facing is its poor bio-availability. Resveratrol is very quickly metabolized, usually within 30–60 minutes after consumption. Researchers are currently looking at ways to address this problem and to potentially use resveratrol as a viable treatment for skin cancers and diseases, It's early days yet but certainly one to watch out for.(10)
Another compound with strong antioxidant properties is coenzyme Q10 or ubiquinone. This compound is found in every living cell of an organism. It plays an important role in the mitochondria, which are the powerhouses of our cells generating energy. One the mechanisms of ageing is the result of mitochondrial damage caused by free radicals. Coenzyme Q10 activates defense mechanisms, protects body cells from oxidation, and stimulates metabolism and regeneration. It accelerates cell renewal and delays the aging process.
In a double-blind, placebo-controlled study, 33 healthy subjects were given 50 and 150 mg of CoQ10 daily for 12 weeks. The results showed that the intake of CoQ10 limited seasonal deterioration of visco-elasticity and reduced some visible signs of aging. The study also determined significantly reduced wrinkles and improved skin smoothness. Supplementation with CoQ10 did not significantly affect skin hydration and dermis thickness.(11)
Recently, there has been a lot of interest in green tea because of reported health benefits. Tea leaves contain varying amounts of polyphenols, particularly flavonoids. There are four main flavonoids as follows:
A review of numerous studies with Green tea has concluded that both oral consumption and topical application of green tea protects against inflammation and chemical or UV-induced carcinogenesis. Research on epigallocatechin-3-gallate has also revealed promising results in reducing AGE-induced pro-inflammatory changes.(12)
The content of AGEs in food is highly dependent on the method of preparation, like cooking time and temperature. Fried food contains far higher amounts of AGEs than boiled or steamed food as can been seen in Table 2 above. Whether on the grill, in a skillet, or in the oven, browning or charring foods is an indication that AGEs are present.
Approximately 10–30% of ingested AGEs are absorbed in the circulation and dietary AGEs directly correlate with serum levels of AGEs and inflammatory markers in healthy human subjects, respectively. The formation of new dietary AGEs during cooking can be significantly reduced by cooking with moist heat, using shorter cooking times, cooking at lower temperatures, and by use of acidic ingredients such as lemon juice or vinegar. Lets take a closer look at some tips we can use for reducing for reducing AGE’s
Marinate meats in acidic compounds such as lemon, vinegar or wine. The acids will inhibit the formation of AGEs. For example, beef marinated for an hour in a mixture of lemon juice and vinegar will produce fewer than half the AGEs when cooked compared to unmarinated meat.
Chicken or beef cooked in a pot at a lower heat will have significantly less AGE’s than if it was roasted or fried. Just don’t brown the meat first. Another benefit of using a slow cooker is that more nutrients are retained compared with many other cooking methods, and recipes tend to include more vegetables. It can also be more convenient.
Keep It Moist
Steam, stew, poach and braise meats instead of roasting, frying, grilling or broiling. Poaching or steaming chicken cuts AGEs by more than 80% compared to roasting or broiling.
More Home Cooking
Preparing a meal at home gives you more control on the ingredients and how it is cooked. Heavily processed foods tend to contain more AGEs than whole and minimally processed foods.
We’ve covered some ground in this article focusing on the prevention of skin aging and how we can combat aging from the inside with nutrition and cooking methods to reduce AGE’s and oxidative stress that cause premature skin aging. In the next article, we’ll take a look at how we can protect our skin from the outside with topical lotions containing natural antioxidants.
Sports & fitness nutritionist, researcher and author on a mission to improve the human condition. Focusing on evidence-based and outcome-based nutrition, training, mindset & environment