For all the time and energy (and, let’s be honest, money) that goes into keeping your hair healthy, it’s a little unsettling to think that your scalp is crawling with teeny tiny organisms — bacteria, fungi, yeasts. But by this point, you likely know your entire body is crawling in all sorts of microbial bugs — a single square centimeter of skin can host up to a billion microorganisms — and this is a good thing.
The microbiome — the ecosystem of the trillions of bacteria, fungi, yeasts, and other bugs that help keep your body’s vital systems in balance — has become of particular interest in research labs and beauty aisles alike for all that it does to impact your health. When this ecosystem is in balance (i.e. there are more “good” bugs than “bad” bugs), the microbiome helps keep everything running smoothly: Your gut microbiome impacts everything from digestion to mental health; your skin microbiome helps protect you from pathogens and supports a healthy immune system; your genital microbiome helps keep you infection-free.
Essentially, every part of your body has a microbiome working to keep things in harmony. Including your scalp.
What is the scalp microbiome?
The scalp microbiome (as you can probably guess) is vital for keeping your scalp and hair healthy. Like the skin microbiome, it provides the first line of defense against harmful pathogens. The main difference between the two ecosystems is essentially what type of microbes live in each area, explains William Gaunitz, FWTS, a certified trichologist and founder of Advanced Trichology. “The scalp has a prior propensity for yeast whereas the skin and other locations have a higher level of bacteria than yeast,” he says.
Signs your scalp microbiome is unbalanced
The most noticeable role of your scalp microbiome is how it keeps your scalp and hair healthy — or not. “Common symptoms of an out-of-balance scalp microbiome are dandruff, flaking, itching, irritation, and white bulbs attached to hairs ejected from the scalp,” says Gaunitz, which is a sign that the strand was lost from the root, not simply snapped or broken off. An out-of-whack scalp microbiome can also inhibit new hair regrowth and lead to dry, brittle strands.
Maintaining the right balance of yeast and bacteria is particularly important for preventing inflammatory conditions like eczema on the scalp, adds Gaunitz.
How to keep your scalp microbiome healthy
There are a lot of factors that keep the scalp microbiome happy and living in harmony, but “diet and nutrient levels in the blood have the highest influence,” Gaunitz says. “Nutrients such as vitamin D3, iron, and zinc play a large role in the ability of the body’s immune system to fight off microbes that are unbalanced on the scalp.”
This means a scalp-healthy diet includes lots of dark leafy greens and cruciferous veggies like broccoli; meat or meat alternatives like beans and tofu; and plenty of nuts and seeds. “Different diets that include low meat or total meat elimination, those that are low omega fats, and those that are high in sugar, will all contribute to an exacerbation of an out-of-balance scalp microbiome,” Gaunitz says. (If you’re concerned your diet may be the culprit behind your scalp woes, a blood test measuring iron, ferritin and vitamin D3 can confirm. Talk to your doctor or dermatologist to come up with a testing and treatment plan.)
This doesn’t mean that going vegan will doom you to an unhealthy scalp. But it is a reminder that minding your nutrient balance is important for every single system in your body. “Supplementation including vitamin D3, highly absorbable iron, and omegas would be ideal for these types of situations,” Gaunitz says. (Sugar also feeds yeast, which can trigger inflammatory flare-ups like eczema, so reducing sugar and alcohol consumption can also help.)
Probiotics and prebiotics — supplements that help keep your body’s microbiome healthy by seeding it with “good” microorganisms and the fiber they feed on — can also be helpful for hair and scalp health. But only when taken as a supplement, Gaunitz warns. “Topical use of probiotics will have no impact,” so be wary of “probiotic” shampoos and serums.
Wash with the right stuff
While nutrition is huge for scalp microbiome health, it isn’t the only thing that can influence it. “Other lifestyle factors like not washing your hair regularly or adding oily tinctures to the scalp can influence it further,” Gaunitz says. In that case try an AHA/BHA-infused, rinse-off serum to clarify the scalp of product buildup, excess oil, dead skin, and pollution for a cleaner, healthier-looking scalp and refreshed hair.
Importantly, once your scalp microbiome is out of balance, it becomes easier to further irritate, so sticking with a scalp healthy routine is key. Gaunitz recommends washing your hair every 48 hours with a shampoo containing neem oil or tea tree oil, both of which are anti-fungal and will help support the healthy microbiome balance of bacteria and yeast on your scalp.
Coconut oil (also anti-fungal) might be particularly powerful for keeping your scalp microbiome in balance. A study published in 2021 examined how the topical application of coconut oil impacted the scalp health of 140 women, half of whom had dandruff and half of whom did not. After applying coconut oil to their scalps for 12 weeks, the researchers found a significant decrease in dandruff for those who had it and a boost in microbiome balance across the board.
Get a healthy amount of sun
In the short, dark days of winter, lack of sun exposure can cause vitamin D deficiency, which can trigger a host of health problems (seasonal affective disorder, osteoporosis, and heart disease) including poor scalp health. “Getting out in the sun for 15 minutes per day helps support healthy vitamin D3 levels,” Gaunitz says.
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