Many people take them to boost gut health, but now probiotics — or ‘friendly’ bacteria — are being put in creams and sprays to treat skin conditions such as eczema and acne.
It’s well known that our guts harbour millions of bacteria, but our skin is host to huge numbers, too, which are all thought to contribute to skin health.
‘There are about 100,000 bacteria per square centimetre on the surface of the skin, and these are made up of 200-300 different types of bacteria,’ says Richard Gallo, a professor of dermatology at the University of California San Diego, and a leading researcher in this field. ‘The theory is that when the skin is diseased, there is less diversity of bacteria — as happens with the gut.’
This can lead to an imbalance in the bacteria population, or microbiome.
‘Treating’ the problem with good bacteria reduces the number of harmful bacteria possibly linked to skin complaints. Professor Gallo is currently testing an eczema cream that contains good bacteria taken from a patient’s own skin.
He developed it after discovering people with eczema had lower levels of bacteria that combat Staphylococcus aureus (S. aureus), a type of bacterium known to aggravate eczema. People with healthy skin had higher levels of the protective bacteria, known as S. epidermidis and S. hominis.
In a study reported in the journal Science Translational Medicine last month, he and his team isolated samples of these protective bacteria from the arms of five volunteers with eczema and mixed them into a cream. This cream was then rubbed onto the patients’ skin. Professor Gallo found that adding back these beneficial bacteria via the cream ‘drastically’ reduced the levels of S. aureus. He is now running larger trials.
But Professor Gallo stresses that this doesn’t mean the bacteria is the sole cause of eczema.
‘We think that atopic dermatitis is caused both by genes [that make the skin more prone to flare-ups] and by the balance of bacteria,’ he says.
It may be that the skin of people prone to eczema doesn’t encourage the growth of the beneficial bacteria, so the S. aureus is able to take hold. Such findings are very significant, says Dr Miriam Wittmann, an associate professor of inflammatory skin diseases at the University of Leeds, where the role of topical probiotics in eczema is also being researched.
‘I think the potential for this kind of treatment is not a cure per se, but once you have stabilised the skin, it might help prevent flare-ups,’ she says.
‘That is useful as flare-ups can lead to the need for treatment with antibiotics — yet there is a growing issue of antibiotic resistance, so the less we use them the better. Another option for a severe flare-up is immunosuppressants, but these can have side-effects.
‘Using someone’s own bacteria, on the other hand, is much safer.’
Probiotics are also being investigated as a treatment for acne. A paper in the Journal of Cosmetic Science in 2012 found that applying a solution of 5 per cent lactobacillus (a bacteria often found in yoghurt) to the skin helped combat mild acne.
And U.S. firm AOBiome is carrying out trials of a good bacteria spray to treat mild acne. Sold under the name Mother Dirt, it is already on sale in the U.S., but the company hopes to be able to sell it in Europe later this year.
Dr Carsten Flohr, of the British Association of Dermatologists and consultant dermatologist at London’s Guy’s and St Thomas’s Hospital, says similar probiotic-based treatments work differently depending on the skin complaint.
‘Whereas with eczema we think the bacteria might have a preventative role, with acne, the bacteria play a different role.
‘The inflammation that occurs with acne is partly due to the presence of bacteria and the skin overreacting to that. However, there are other factors — such as hormonal changes in adolescence that increase the amount of oils produced in the skin.’
He points out that these treatments have to be more sophisticated than simply smearing yoghurt on your face.
‘The skin is a very complex environment,’ he says. ‘And the balance of bacteria that live there is very well suited to that environment, which is why it is better to use bacteria that normally exist on the skin rather than introducing different types.
‘The use of bacteria to help with these skin complaints is definitely realistic,’ he adds.
But since a balance of bacteria can help our skin, should we be avoiding frequent washing of our hands and face?
Professor Gallo says not, as studies show ‘standard hygiene doesn’t alter the microbiome’.
‘The microbiome of the skin is so important. We would not have evolved so that when you jumped into a lake you washed it off.’