Salmon sperm to bird droppings: The science behind bizarre skincare trends

A flurry of bizarre beauty therapies are trending on social media. But does the scientific research suggest they can be taken at face value?

At the You & I Clinic in Seoul, South Korea, one of the most requested skin texture treatments involves injecting tiny fragments of DNA from salmon sperm into the dermis, the skin's thick middle layer which houses the blood vessels, nerves and glands.

"The goal is not volume, like a filler, but skin priming or biostimulation, which involves supporting a healthier dermal environment and recovery," says Kyu‑Ho Yi, an aesthetic physician at the clinic and an adjunct professor at Yonsei University.

The idea might seem bizarre, but Yi says the concept actually originates from the world of regenerative medicine and wound healing, where DNA fragments from fish gained attention for their potential to stimulate tissue repair in people with facial scars from combat injuries. 

Scientific data remains relatively sparse, but some studies suggest that the treatments – which harness the salmon sperm's purified polynucleotides – may help reduce the appearance of fine lines.

They've been shown "to help improve skin hydration, plumpness, texture and wrinkles", says Joshua Zeichner, associate professor of dermatology at Mount Sinai Hospital, in the US, who has also worked for skincare companies as a consultant. "It's unclear how someone first decided to try this as a skin treatment, but nonetheless, it's being used."

With South Korea now viewed as a trendsetter in aesthetics – otherwise dubbed as the K-Beauty craze – the supposed benefits of salmon and other fish sperm injections have spread around the globe, encouraged by a flurry of celebrities ranging from Charli XCX to Jennifer Aniston. Their popularity has risen alongside a collection of other odd-sounding treatments, which include facemasks made of bird droppings and blood-sucking vampire facials. 

But do these unusual, trendy skincare regimens actually work?

Ancient beauty

A quick glance through the history books shows that skincare has a long and storied history of seemingly odd practices. The Egyptian queen Cleopatra is rumoured to have bathed in sour donkey milk. In Myanmar, women have applied a paste known as thanaka to their faces for centuries, made from ground tree bark, both as a decorative practice, and to shield their skin from sun damage. One notorious Roman remedy for blemishes involved grinding up the guts of a small crocodile. 

Yet modern skin science suggests that at least a few of these ancient beauty therapies have stood the test of time, with ingredients like turmeric, tiger grass and seaweed popping up in modern-day products thanks to their anti-inflammatory and skin-hydrating effects.

In 2022, a study examined various skincare practices from 12th-Century Italy that had been cited in the writings of a famed female medieval medical practitioner called Trota of Salerno. The researchers noted that many of the suggested ingredients, such as fava beans and vinegar, are now considered to be effective for facial cleansing, exfoliating, and treating dry skin. An extract of tartar oil called tartaric acid, for instance, is now a common ingredient in modern skincare.

Geisha facials and menstrual masking

It's not just plants, herbs and minerals found in nature. The so-called "Geisha Facial" involves taking excrement from nightingale birds, sanitising it using powerful ultraviolet light, mixing it with other chemicals such as an exfoliant and a brightener, before applying it like a face mask. This coprocentric technique originates from a centuries-old Japanese discovery that the droppings of Japanese bush warblers, a type of nightingale, could be used as a dye remover in fabrics. This then led to the droppings being used by Japanese female entertainers for skin whitening and removing their heavy makeup.

Nowadays, it's popular in various clinics around the world as a way of brightening the skin, and again, there could be some sound science behind it. According to Zeichner, nightingales leave particularly high concentrations of urea in their droppings, a chemical with such potent skin softening qualities that it's commonly incorporated into moisturisers. 

It also contains high concentrations of the amino acid guanine. "Amino acids have been shown to have hydrating and brightening benefits," says Zeichner. "But it's important to say that these [treatments] use purified, modified nightingale droppings. You shouldn't just scoop up bird poop off the street and rub that onto your face." 

Another important point to note here is that many studies into these treatments have been funded by the beauty industry or conducted by scientists directly employed by these companies. 

Researchers are less enthused, however, about another supposed DIY skincare treatment which has been doing the rounds on TikTok, namely menstrual masking – or period blood face masks. While one 2018 study suggested that plasma derived from menstrual fluid might be capable of enhancing wound healing, compared with regular blood plasma, Beibei Du-Harpur, a dermatology researcher at King's College London, isn't convinced. 

"No clinician would ever recommend that," says Du-Harpur. "I think this is just one of those TikTok trends which has emerged because of the shock factor and people wanting to get views."

Vampire facials and platelet-rich plasma

Du-Harpur is more optimistic about the potential of platelet-rich plasma (PRP) injections, sometimes dubbed the "Vampire Facial", for skin rejuvenation. 

This procedure involves taking the patient's own blood and using a centrifuge to separate it into fractions. This process helps to concentrate the numbers of growth factors – a special group of proteins which instruct cells to grow, divide and repair – in the plasma, before injecting the blood back into the facial skin using microneedles.

Serenity Strull/ BBC/ Getty Images

The potential of harnessing the body's own growth factors in a regenerative fashion is generating active interest across various areas of medicine, from treating osteoarthritis and other joint problems to alopecia and wound healing. While the evidence for skin health remains mixed, some studies have found that it enhances skin elasticity in people in their 50s and 60s, and reduces wrinkles and pigmentation.

"There's quite a lot of variability in how successful PRP is for people," says Du-Harpur.

She says that this is due to differences in the machines used for the centrifuge process, and because some people might have higher or lower concentrations of growth factors, or different types of growth factors naturally concentrated in their blood. 

"So sometimes it's shown to be quite effective, sometimes less so," says Du-Harpur.

The future of skin care

While even the most bizarre of skincare routine fads may have some scientific backing, scientists think that options for the next generation of skincare therapies will involve, among other things, finding new ways to optimise collagen supplementation.

One recent industry-funded study used supplements with amino acids that had been specially engineered for collagen replacement. It elicited not only improvements in skin texture, hydration, and elasticity over the course of six months, but also an average reduction in biological age of 1.4 years, according to DNA tests on the patients' saliva. The researchers concluded that collagen supplements containing this particular balance of amino acids could potentially not only improve skin health, but also other aspects of health.

The findings chime with research showing that the skin has a hitherto under-recognised role in the body's overall health, through processes such as inflammation, but the study still concluded that a lot more research is required on the processes involved. (Read more about the curious ways your skin shapes your health.)

Other new therapies are exploring novel ways of manipulating the skin microbiome, the populations of invisible microbes that live on our faces and contribute heavily to the inflammation present in our skin. The potential treatments include prebiotics designed to nourish the useful bacteria within our skin microbiome, and also postbiotics, the chemicals naturally produced by the bacteria, says Zeichner. Last year, researchers in South Korea published the discovery of a bacteria found in blood which produces potentially useful postbiotics capable of reducing inflammation, oxidative stress and collagen damage in skin cells, albeit only in petri dishes. 

But to become established treatments, Zeichner says, any new skincare regime must ultimately prove it is more effective than any of the tried-and-tested solutions commercially available for decades.

"The question still is, do the fad treatments truly deliver better benefits than the traditional skincare products that we have on the market?" Zeichner says. "That's still a bit of an open question." 

Rather than spending $500 (£375) on a facial for a one-time improvement in hydration and glow, Zeichner would much prefer someone stick to a consistent routine with sunscreen in the morning to protect the skin from environmental damage, he says. And hydration and repair in the evening with a night moisturiser and a collagen-stimulating ingredient like retinol. 

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