Slugging, beef tallow and salmon sperm: A dermatologist answers your questions

There's plenty of noise out there about the effectiveness of urea, beef tallow and skin creams that penetrate 10 layers deep - but how much of it stacks up?

Dermatologist Dr A. J. Seine, who is in private and public practice in Hamilton and Tauranga and is a spokesperson for the NZ Dermatological Society, looks at the evidence.

He turned mythbuster on Sunday Morning as host Jim Mora, and listeners, peppered him with questions.

An advert for a skin care product promises to lock in moisture 10 layers deep? Can creams do this?

“I think the thing to remember is when you talk 10 layers deep, our skin is probably about anywhere 10 to 20 cells or layers deep anyway before you start getting to anything more significant down to the dermis.

“So, when you're saying that you're penetrating 10 layers deep, you're really only getting down maybe a few micrometres. I'm never entirely sure what they mean and what level they're specifically saying when they're talking they get down that deep.”

It's a catchy marketing line rather than having any true basis in science, he says.

“We know that in order to deliver these type of topical treatments that have a meaningful effect, you can use fractionated treatments. So, there's lasers and other things like radio frequency micro-needling that can create little channels within the skin and that enables products to penetrate deeper."

How much science is there to support injecting tiny fragments of DNA from salmon sperm into the dermis to stimulate the skin?

“Surprisingly, it's not just science fiction, there's actually evidence behind it. It's a new class of treatments known as biostimulators, and that's largely where we're seeing the cosmetic industry heading towards.

“It stimulates the fibroblasts, fibroblasts are like the builders within your skin, their job is to put down collagen and get the hyaluronic acid, the compound that holds and binds water, to give your skin that plump look. It also can downregulate inflammatory cytokines, so things that are causing inflammation within the skin."

Urea from the urine of Japanese bush warbler birds to brighten and soften skin, any evidence?

“You can buy urea in safe, sterile, formulations. Urea is a very powerful tool to use in dermatology. So, in low concentrations, 5 percent to 10 percent, it acts as a humectant -in other words, it binds water.

“But you don't need to be walking in the bush and finding an animal, and please don't go and use your own urine on your face. There's too many other things in there that will cause risk and irritation to your skin.”

Is beef tallow good for your skin?

“Everyone wants to use the natural things, don't they? And look, beef tallow, no doubt it will have moisturising properties.

“It is thick, it's got sort of fatty acids to try and mimic what our natural oils and fats are doing in our skin. But the problem is it's an unregulated product at the moment, so, we don't know which formulation is right.

“We don't know where the source of the beef tallow is coming from. If you're using it in areas like on your face, it will occlude the face and so it can trigger acne quite badly to occur. It can go rancid.”

Dermatologists are advising stay away from it for now, he says.

Does slugging, the trend to thickly coat your skin with stuff like zinc oxide at night, work?

“I think the problem with slugging comes where if you're putting too many heavy and greasy things onto your skin with the aim to try and lock in moisture, that you are only going to cause more irritation.

“You can cause occlusive folliculitis, which is where you're sort of trapping things around the hair follicle and they get inflamed.

“If you have dry skin, then look for a single product that can mimic the natural skin, so the skin ceramides, which are part of the fatty acids and oils that are in our skin, that can provide deep hydration, but you don't necessarily go put layer upon layer of different products on that might cause problems for you.”

Listener questions:

I'm a 76-year-old male for the past six months, my skin has itched, mainly on back and thighs. I've tried cutting out eating nuts, changed soaps and washing powder, no longer wear microfibre fabrics, two antihistamine a day is the only thing keeping it at bay?

If there is an outward sign, such as a rash, see your GP, Seine says.

“To try and figure out what's causing that, because inflammation of the skin will lead to itch.”

If there's nothing to see on the skin, it is one of the most frustrating conditions to treat for the person and dermatologist alike, he says.

“If you just have itch and there's nothing to see on your skin, it's usually a nerve issue. Something has gone on in the skin or with your nerves as part of the ageing process to cause some sort of disruption.

“And what ends up happening is the nerves might be misfiring or malfunctioning compared to how they should. And the brain then starts to rewire and misinterpret that as itch.”

Non-sedating antihistamines can help, he says, as does making sure the skin barrier is intact by using soap-free washers to not dry the skin out and irritate it further.

“Don't use antibacterial soaps. We know there's increasing problems with those in terms of developing antibiotic resistance and skin irritation. And then moisturising. Getting on a good moisturiser a couple of times a day, top to toe, to again try and reduce the amount of water that your skin is losing and reduce the risk of that irritation.”

If that's not cutting it, then you might need to be referred to a dermatologist, he says.

“To talk about how we can try and get those nerves to retrain themselves.”

Is it possible to get rid of rosacea without an application of Rosex everyday?

Rosacea is a chronic problem, he says, and there are two different types: erythematotelangiectatic which is redness from chronic inflammation and papulopustular caused by a more acne-type problem.

“Rosex is a topical antibiotic known as metronidazole and I generally don't use it. I find that it tends to cause a bit of irritation and not really fix things.

“I think the important thing to understand in the first instance is that rosacea is a chronic problem and we don't have a good cure.”

If you have the redness part, then lasers and intense pulsed light (IPL) seal off blood vessels, he says.

“There are also some really good ways to restore the skin barrier - using a soap-free wash, using a moisturising lotion to make sure that your skin's not drying out to reduce that inflammation.”

He recommends azelaic acid in formulations of 15 to 20 percent.

“You can pick those up at the pharmacy that you can use a couple of times a day.”

If you've got the pimple variety of rosacea, prescription medications are the go-to treatments, he says, so check in with your GP.

Are barrier creams better than moisturisers?

“A lot of the simple moisturisers that you buy form a seal on the top of the skin to try and reduce the water loss. And that can work quite nicely if you've just got some mild or normal skin to lock in that moisture.”

For extremely dry skin, natural skin ceramides might be the answer, he says

“There are products out there that have antimicrobial peptides which are helping to reduce inflammation, rebalance the skin microbiome to help that skin barrier repair itself.

“There are also other ones that have simple anti-inflammatory properties, again, to interact with that immune system, seal that skin, and help that skin microbiome recover as well.”

My skin was damaged young when I sunbathed, I often used coconut oil on it. I have Māori ancestry, so more melatonin protection than Pākehā. I'm 69, and there are so many face creams on the market. What would you recommend?

Sun damaged skin is going to be a less effective barrier, he says.

“It's not going to hold onto moisture as well, and you also have broken down the collagen and the elastin, so those supportive fibres within the skin.

“A very good moisturiser is going to be key to help lock in that moisture. You don't have to go spend hundreds and hundreds of dollars if you don't want to. There are good brands out there, like I said, natural skin ceramides, they can do a great job for your skin.”

And keep using sunscreen, he says.

“SPF 50+, broad spectrum UVA and UVB, getting it on every day with all the other sun smart behaviour, covering up, seeking the shade - that's really important.”

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