So far we’ve seen there’s a variety of products that share the aim of increasing collagen levels to fight skin ageing. These range from supplements and cosmeceuticals actually containing broken down collagen, to skincare products containing vitamins C, E, B3 and retinoids. Another group of molecules with potentially big impacts are phytoestrogens… at least, amongst post-menopausal women or other people with low oestrogen levels. Here we look more closely at different types of phytoestrogens, how they work, and the best way to use them.
- A deficiency in oestrogen post-menopause accelerates the ageing process, including loss of collagen from the skin.
- In cases of deficiency phytoestrogens appear to boost collagen levels, and to be safer alternatives than oestrogen replacement.
- Eating plenty of fruit and vegetables, nut and seeds can ensure your body receives the whole spectrum of phytoestrogens, from flavonoids, stilbenes, coumestans to lignans. However, the question over how much reaches the skin has to be answered.
- Use of phytoestrogens in topical skincare products may be beneficial, but we need more scientifically rigorous research to clarify this, and to be sure of their long term safety.
The fight for collagen: oestrogen versus phytoestrogens
It’s not something I had given much thought to before, since I’m still in the stage of begrudging my regular fluctuations in oestrogen- but this hormone is very valuable to skin condition. The skin is full of oestrogen receptors. Importantly, when oestrogen binds to these receptors, a series of events occur which help fibroblasts (collagen-producing cells) function normally. It also helps skin cells retain moisture, for example by preserving hyaluronic acid.
Once menopause hits women, oestrogen deficiency means the ageing process accelerates. It is estimated that each year post-menopause 2% of collagen is lost, and skin becomes 1.13% thinner. In the first five years post-menopause, up to 30% of collagen types 1 and 3 (the principal components of skin) are believed to be lost. The use of oestrogen replacement therapy can reduce the impact of ageing, but they also place women at elevated risk of breast and uterine cancer. That’s where phytoestrogens come in.
Phytoestrogens are plants’ answer to oestrogen. i.e. they are molecules found within fruit and veg, nuts and seeds, even wine, tea and botanical supplements. They are polyphenols that have similar chemical structures to human oestrogen (estradiol). Thus they bind to oestrogen receptors and have similar anti-ageing effects on the skin- seemingly without the associated risks (although more research should be done to allow us to be certain about this). Thus they’re valuable among post-menopausal women, and presumably others who are oestrogen deficient. This gives me a new understanding of why, as a teen, I’d see senior women in my life chowing down on soy and linseed bread. I just thought it was delicious.
Delving deeper: phytoestrogens and their impact on collagen
Phytoestrogens seem to increase or maintain the collagen content of the skin by increasing synthesis of precursors (procollagens), inhibiting collagen-degrading enzymes (MMP’s), acting as antioxidants and offering some protection from UV damage. At least they have these effects in animal and cell culture studies, with all their inherent limitations in applicability to us.
However, not all phytoestrogens are the same. Different scientific authors use conflicting classification systems. For the sake of simplicity and clarity, we’re going to divide them into four groups, each of which has its own unique chemical structure: flavonoids, lignans, stilbenes, and coumestans.
Flavonoids are colourful antioxidant molecules giving plants their distinct hues, and have skin enhancing effects. They can be further subdivided into smaller groups of phytoestrogens including flavones, flavonols, flavanones, isoflavones, neoflavonoids, flavanols (or flavan-3-ols or catechins), anthocyanins, and chalcones. Here we’ll look at three key ones.
Isoflavones include glycitein, genistein, daidzein, formononetin, and biochanin A.
Soybeans are one of the most renowned sources of isoflavones such as genistein and daidzein. Fermented soy foods often contain higher amounts. Genistein’s structure is very similar to humanoid oestrogen, which may explain why it seems to be most potent of phytoestrogens.
Other legumes such as lentils and red clover provide some isoflavones.
Animal studies have shown that dietary isoflavones from soy have increased collagen lay down, increased collagen fibre thickness, inhibited matrix metallopeptidases (MMP’s), had antioxidant effects, and reduced wrinkling upon UV exposure. Red clover extracts have also been seen to increase collagen synthesis in animals. Unfortunately human evidence is mainly limited to small human studies, which only suggest a general improvement to the appearance of the skin after a period of isoflavone supplementation. One small randomised controlled trial among women aged 45-55 specifically examined effects on collagen: it showed that topical genistein increased types 1 and 3 collagen over 24 weeks, albeit to a lesser degree than topical oestrogen. Unfortunately there is a notable lack of the stringent clinical studies that are expected in other fields.
It’s also interesting that while research has shown that low levels of genistein stimulate collagen synthesis, high levels can hinder it. This may be related to the observation that phytoestrogens don’t have uni-directional effects. As well as mimicking the effects of oestrogens, in some situations they block natural oestrogen from doing it’s thing… by occupying the oestrogen receptor.
A molecule by the name of equol has also received increased attention recently as a potent antioxidant and a stimulator of types 1 and 3 collagen, and inhibitor of MMP’s. The isoflavone daidzein can be converted into equol within the gut. Alternatively, it can be obtained from white cabbage.
Flavonols (or catechins)
Green tea contains a variety of healthful nutrients and phytochemicals, but it is their antioxidant flavonols that are thought to be responsible for a collagen-enhancing effect. Fresh leaves are approximately 30% flavonols (by dry weight). Epigallocatechin gallate (EGCG) is the most common, comprising approximately 50-80% of the flavonols in green tea.
Several studies, in animals and cell cultures, suggest that green tea supplementation increases collagen content, inhibits MMP production, and may increase the viability of collagen-producing fibroblasts. Exactly how this is accomplished is not known.
Green tea may also protect from UVB damage. A cell culture study has shown that green tea extract delivery, prior to UVB exposure, has increased fibroblast viability by 71%. Applying green tea topically has been seen to reduce sunburn and DNA damage in human studies, although the direct effect on collagen was not assessed.
Another form of flavonoid, anthocyanins are concentrated in plant foods including blackcurrants. Delivery of blackcurrant extract and 4 types of anthocyanins to fibroblast cell cultures obtained from healthy women were all seen to stimulate expression of collagen. The blackcurrant extract also decreased expression of an MMP. The authors noted that this supports the use of blackcurrant extract and anthocyanins in the diet. However, delivery of a substance to cells in a culture, and its subsequent actions, does not necessarily reflect what would happen within the body. Each person may absorb and metabolise phytoestrogens differently, thanks to differences such as diet and gut microbiome.
The most well-known stilbene is resveratrol, which is found in the skin of grapes, as well as peanuts. Plants produce stilbenes upon stress or microbial infections. As with other phytoestrogens, resveratrol has been seen to act on oestrogen receptors and can be seen to increase collagen production, and inhibit its breakdown by MMP’s.
Coumestans occur in the sprouts of legumes such as alfalfa, mung bean and soy. They include coumestrol. Coumestrol is generally considered as good at binding to oestrogen receptors as genistein, for binding with oestrogen receptors, whereas some researchers suggest they even exceed genistein and daidzein in oestrogenic activity.
Flaxseed (i.e. linseed) and sesame seeds are good sources of lignans. They can also be found in other seeds, whole grains, beans, fruit and vegetables. Examples of lignans are enterolactone and enterodiol.
To eat or apply to the skin?
As mentioned above, the use of phytoestrogens is considered a good alternative to oestrogen replacement therapy among post-menopausal women. There appear to be some benefits to phytoestrogen-containing cosmeceuticals, but there may also be risks that are as yet beyond the grasping hand of confirmed scientific knowledge.
One reason that might support the use of applying phytoestrogens to the skin is the observation that it takes the body less than 24 hours to excrete isoflavones, once they’ve been ingested. I was also unable to find clear information on how phytoestrogens are delivered to the skin, via the gut and bloodstream. A controlled multicentre study within Europe found that a cosmeceutical containing isoflavone increased collagen synthesis and reduced collagen breakdown by MMP’s, thus reducing facial wrinkles by 22% and skin thinning by 24%.
However, most products have not been tested in randomised controlled trials, and so the information we have is incomplete at best. We still don’t know enough about the risks and benefits of using phytoestrogens as active ingredients in skincare products, especially over the long term. There have in fact been some studies suggesting topical application may have carcinogenic risks, although others dispute this.
In contrast, most epidemiological and experimental evidence points to high dietary intake of phytoestrogens having either no association or a negative association with hormone-dependent cancers. So eating may be the preferred course of action, with potential collagen-enhancing and other effects.
Animal and cell culture studies support a role for phytoestrogens in increasing collagen levels amongst oestrogen-deficient people, although additional robust human studies are greatly desirable. In general, use of phytoestrogens in skin care products remains controversial, so you should tread with caution. It is particularly recommended that people with a history of breast cancer avoid using phytoestrogen containing skincare products, in case they stimulate growth of existing tumours. In general, oral consumption seems to have reasonable effects, so you should aim to have a high intake of plant foods such as fermented soy products, fruit and vegetables, nuts and seeds. This will give you countless benefits beyond any impact on your skin’s collagen.
Where do you get your dietary phytoestrogens?
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