Which extracts do you need in your products?
There are dozens of products promising to reverse the effects of aged skin and restore collagen, but most are not formally tested and trialed. Below is a list of the most commonly hyped ingredients, their trial results and their effectiveness on collagen synthesis.
The skin protects itself with naturally occurring antioxidants, such as vitamins A, C, and E, squalene, and coenzyme Q-10. These natural antioxidants become depleted with age and especially UV exposure. UV radiation also forms thymine dimers in the DNA. These are usually repaired by the body, but if the damage continues, there is ever more chance of carcinogenesis.
The best-tested skincare staples include the following: (This does not cover SPF ingredients and concentrates mainly on collagen and UV-damage repair).
Vitamin A naturally occurs in skin. Retinoic acid is the biologically active form and applying this topically has been shown to improve collagen metabolism, but it can be very irritating. However all vitamin A derivatives are converted into retinoic acid on the skin (retinol, retinaldehyde, and retinyl palmitate). Fewer trials have been carried out on these, but a 1% retinol cream was shown to increase collagen synthesis. Another trial on retinyl palmitate, after two weeks application, found an increase in protein and collagen, with the same cellular changes observed in retinoic acid, without the same irritation (Glaser DA – PubMed. 2004)
These have had far fewer trials carried-out, but the results are encouraging, albeit not directly on collagen synthesis. Topical Niacinamide for 12 weeks significantly improved wrinkles and elasticity. Nicotinamide, in in-vitro studies increased the synthesis of ceramide. DMAE, another B vitamin, applied at 3% improved both wrinkles and sagging skin.
Again, this has been comprehensively studied and topical vitamin C- L-ascorbic acid – has proven to be a cofactor for collagen synthesis. A 12 week study revealed an increase in the Grenz zone collagen, (just under the epidermis) and type I collagen. A 5% vitamin C solution applied for 6 months resulted in measurable increases of elastin, type I and type III collagen. A 3% solution had similar results.
Vitamin E (tocopherols and tocotrienols)
This scavenges free radicals, preventing their ability to damage the lipid cell membrane and is protective. But there is little evidence that it can improve collagen directly. However, it does seem to have a synergistic effect when combined with Vitamin C.
Alpha lipoic acid (ALA)
This is an antioxidant that is not naturally found in the skin but is used in anti-ageing treatments. It has been found to repair oxidative damage ( in vitro). A 0.5% solution increased collagen synthesis in the dermis and epidermis (in animals trials). In a randomised, double-blind trial, 5% alpha-lipoic acid was applied twice daily for 12 weeks and showed 50% decreased skin roughness compared with 40% on the placebo, (both creams also contained 0.3% coenzyme Q-10 and .03% acetyl-L- carnitine.) Self-assessment by patients reported an excellent subjective improvement.
Alpha-Hydroxyl Acids – these must not be used at above 10%, unless by a doctor.
AHAs: (glycolic acid, lactic acid, malic acid, citric acid, tanoic acid, alpha-hydroxycaprylic acid).
The most commonly used are glycolic acid and lactic acid. AHAs thin the stratum corneum by reducing corneocytes – the top layer of surface skin cells- and speed up the normal process of skin cell exfoliation. At high concentrations (20%) they can cause increased epidermal thickness, increase hyaluronic acid, improve the quality of elastic fibres and increase collagen. At concentrations below 8%, the results are still significant, with less irritation. These findings have been reproduced a number of times, but mainly on animal studies. A double-blind clinical trial, in which 8% glycolic acid or 8% L-lactic acid creams were applied twice daily to the face for 22 weeks, demonstrated a significant number of patients had at least one grade of facial improvement in photo-damage compared with placebo (1996, Stiller et al).
A subfragment pentapeptide – palmitoyl-lysine-threonine-threonine-lysine-serine (pal-KTTKS), a synthetic peptide, now patented, is designed to improve collagen and has had excellent results. In randomised t rials, it was found to significantly increase production of type I and type 3 collagen in dermal fibroblasts. It was linked to palmitic acid to enable it to penetrate skin effectively.
Plant polyphenols are responsible for the antioxidant properties found in botanicals. These can be divided into several classes of chemicals: antho-cyanins, bioflavonoids, proanthocyanidins, catechins, hydroxy-cinnamic acids, and hydroxy-benzoic acids. Bioflavonoids are antioxidant, anticancer, and anti-inflammatory. They also inhibit UV-induced connective tissue damage in skin. Anthocyanins, a group of flavonoids, have been shown to decrease UVB-induced DNA damage and decrease cancer formation. Proanthocyanidins inhibit the production of free radicals and inflammatory pathways, such as histamine and prostaglandins. Whilst in-vitro trials are plentiful, few human trials have been conducted on commonly used botanicals. However, anecdotal evidence is encouraging and there is reason to be optimistic about the efficacy of botanicals.
These contain occlusives, humectants, and emollients.
Occlusives prevent transepidermal water loss (TEWL) and are comprised of oils, butter and fats.
Humectants attract water and have a low-molecular-weight (so are easily absorbed). Natural moisturising factors are naturally occurring humectants.
Emollients do not have hydrating properties, but soften desquamating corneocytes, giving a smooth skin surface.
Hydration is important for the overall well-being of the skin. The stratum corneum (SC) contains corneocytes held together by a lipid bilayer. These restrict TEWL and are made up of cholesterol, ceramides and free fatty acids (mostly linoleic acid). Corneocytes contain water-soluble molecules – natural moisturising factors (NMF) and these allow the skin to bind to water. It is this combined action, binding water and preventing water loss, that maintains skin hydration and allows the stratum corneum to be soft and flexible.
As skin ages, there is a discernible decrease in the lipid content of the stratum corneum. This is vital for the skin barrier to repair effectively, so good quality moisturisers are designed to replace these lipids. Most studies are on aged or damaged, dry skin, so the findings may be different for well-hydrated, normal skin. A number of active ingredients can be added to moisturisers to increase their effectiveness. A study demonstrated that Nicotinamide at 2% in a moisturiser, markedly increased stratum corneum hydration when applied on skin with eczema, with a higher desquamation and decreased TEWL. There was also increased biosynthesis of ceramide and essential lipids.
All the ingredients described above can be found in moisturisers, serums and elixirs. Some are very effective and others less impressive, so close examination of the ingredients list is essential before buying a moisturiser. Decide what difference you want to see and how much suffering you are prepared to endure before reading what a product promises. These ingredients are often expensive and you may not need all that you are being sold. If you know what you are looking for, you are less likely to be drawn down a meandering path of promised eternal youth!