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There's folic acid (also known as vitamin B9), castor oil (now found in countless hair treatments) and TikTok's new favourite, rosemary oil. Just how many of these things are actually proven to work, and which ones rely solely on anecdotal evidence?
Firstly, what causes hair loss, thinning and slow hair growth?
It's totally normal to lose hair (we tend to shed 50-100 strands a day) and usually it's nothing to be worried about — unless it's getting you down.
Angela explains that stress is the number one cause of hair loss. "Stress causes your body to constantly be in survival mode," says Angela, "and that has a long-term effect on your hair, since it isn't prioritised by the body when it comes to survival." But hair loss or thinning can often be a sign of a medical condition, such as alopecia areata (unpredictable patches of hair loss). Weight loss, iron deficiency, polycystic ovary syndrome and illness are just a handful of other causes of hair loss and thinning. It's best to visit your GP or a registered trichologist for tailored advice.
Is rosemary oil good for hair growth?
On TikTok there are 119.6 million views for #rosemaryoil, with the majority of videos talking about it in relation to hair health and accelerated growth. Hannah says she "swears by" the ingredient for reducing hair fall, and lots of anecdotal evidence suggests that massaging rosemary oil into the scalp on a regular basis helps to fill out the hairline and encourages growth in sparse patches. But at the moment, it's just that — anecdotal.
"So far [the benefits of rosemary oil for hair growth] has not been scientifically proven on humans," says Angela, referring to a study on mice, where rosemary oil was used to speed up hair growth. Angela explains that there has been a human study, albeit only on 28 people, each one of whom had a scalp condition called alopecia areata (an autoimmune disorder which results in patchy hair loss). Hair loss caused by alopecia areata is very different from other types of hair loss or slow growth so the findings were limited. "So far, when it comes to science there is no proof," says Angela of rosemary oil.
All is not lost, though. It could be that the act of regularly massaging oil into the scalp is the catalyst that stimulates new hair cells. Hannah praises scalp massagers in particular. "You can use rosemary oil by massaging it into your scalp for five minutes and leaving it on for a minimum of 15 minutes," she says. Hannah also rates rosemary oil for its antibacterial benefits for the scalp and hair. Plus, it can be very nourishing on dry hair strands. That's why so many brands are infusing it into shampoos and conditioners. When it comes to hair growth, however, the science just isn't there.
Is castor oil good for hair growth?
Castor oil is a vegetable oil derived from castor beans. It has highly moisturising properties — particularly for natural hair, which tends to be drier — but Hannah and Angela agree that it will not stimulate hair growth. There is no scientific evidence to suggest otherwise, despite TikTok coming through with countless anecdotes. If your hair is very dry, Hannah says that occasionally using castor oil can help maintain its health but the oil is notoriously thick and can create buildup, causing your lengths and scalp to become greasy quickly.
If you're still swayed by the ingredient, try it in a pre-wash treatment designed to be used before shampoo to ensure the lather doesn't strip your hair and scalp completely, like Fable & Mane HoliRoots Hair Oil, $87.12. R29 also rates Shea Moisture Jamaican Black Castor Oil Strengthen & Restore Hair Treatment Mask, $18.86, and Philip Kingsley Elasticizer Deep Conditioning Treatment, $72.75, which are both rinse-off treatments and condition hair deeply.
Are peptides good for hair growth?
Peptides are little proteins, and proteins can regenerate both skin and hair. There are lots of different peptides, some that work on the hair and some that are better for the skin. In haircare, you're likely to hear buzz around copper peptides and pea protein in particular.
"Certain peptides fight inflammation," explains Hannah. "When inflammation occurs on the scalp, it can impact the growth phase of your hair." Some peptides can soothe this inflammation, nipping hair loss in the bud. Hannah rates pea peptides in particular for helping to smooth the hair follicle and providing fullness, making hair soft and shiny. "Pea protein has essential vitamins and minerals, such as iron and calcium," says Hannah, "which help boost hair quality and improve hair growth." She adds that the production of keratin, which makes hair strong, can be boosted with the help of pea protein. Not only will this repair the hair but it also promotes healthy new hairs and protects them from environmental aggressors like pollution and heat.
Try Philip Kingsley Density Thickening Protein Spray, $72, or VIRTUE Flourish Density Booster, $71. Hannah is personally a fan of OUAI Scalp Serum, $78, which features acetyl tetrapeptide-3, which studies conclude increases hair growth. R29 also rates The Ordinary Multi-Peptide Serum For Hair Density, $34.20, which boasts multiple peptides and caffeine to boost hair density. The incredible reviews speak for themselves.
Is argan oil good for hair growth?
Studies show that argan oil is effective at protecting hair from damage caused by environmental aggressors such as pollution and UV. It's why you'll spot the ingredient in so many hair products. But just like castor oil, there is hardly any data to suggest that it helps with hair growth.
For smooth, protected hair, opt instead for a leave-in conditioner containing argan oil, such as HASK Argan Oil 5 in 1 Leave-in Conditioner, $14.49. If your hair needs more moisture, treat your strands (not your scalp) to something like OGX Renewing+ Argan Oil of Morocco Penetrating Oil, $25.49, before styling or air-drying. It makes hair soft and smooth.
Angela agrees that using an oil to lock in moisture is the perfect way to give a nice coating to your hair, preventing damage. "It also makes the hair easier to manage," she says, "and gives it an amazing shine."
Is minoxidil good for hair growth?
You might've come across minoxidil in your hair growth endeavours. As it stands, this is one of the only scientifically proven ingredients to stimulate hair growth and, happily, it's available in various high street pharmacies, as well as online. So what exactly is it? "Minoxidil is a vasodilator," explains Angela, "and this means that it widens the blood vessels to deliver more oxygen-rich blood to the hair follicles."
Angela adds that lots of people who are dealing with hair loss need more oxygen to the affected areas to stimulate hair growth. She says that minoxidil is used to spot-treat areas of baldness or a receding hairline, since it stimulates those areas and slows down further balding. It's the active ingredient in popular over-the-counter product Regaine, which comes in the form of a solution and a foam.
Is folic acid good for hair growth?
Hannah says that folic acid — also known as vitamin B9 — is necessary for hair health. Angela explains that it is found in our food, such as spinach, beans, peas, citrus fruit, liver and grains. Unless you're deficient in the vitamin, you're probably getting enough from your diet. "Everything that you're adding to your diet will end up in your pee," says Angela of hair growth supplements which contain folic acid. "Your body only absorbs what it needs." If you're worried about deficiency, Angela suggests getting your bloodwork checked before self-diagnosing the condition of your hair using supplements.
The same goes for biotin (also known as vitamin B7). "There has been a huge trend for biotin in hair growth recently," says Angela. "The funny thing is, I've never had a client who ended up having a biotin deficiency. In fact, humans rarely have it."
Is washing your hair regularly good for hair growth?
Hannah believes that using a shampoo regularly helps to keep the scalp clean. In turn, removing oil and debris from the scalp can promote hair growth. Angela agrees that starting off with good scalp health — and particularly a clean scalp — is key. "Since the scalp is the soil your hair grows on, you want it to be in the best healthy state," she explains. Angela likes a gentle cleanser containing hyaluronic acid, which is an amazing ingredient to keep the scalp moisturised and supple.
Lastly, a leave-in conditioner is key to make sure your hair stays moisturised between washes, says Angela.