Will drinking milk give you spots? How much sun do I need to get enough vitamin D? What’s the best ointment for a burn? Everywhere you look there are articles, advertisements and health advice columns telling you how you should look after your skin — with often conflicting messages.
I’ve worked as a hospital dermatologist for nearly 20 years and based on my clinical experience — and close scrutiny of the scientific evidence — here I explain what really will help keep your skin healthy…
MOST PEOPLE DON’T NEED MOISTURISER
People who have normal skin generally don’t need body moisturisers — their skin is in its own natural balance and doesn’t need adjusting.
But even those with normal skin will notice that with age, skin becomes drier, especially on our hands and lower legs.
This seems to start from the age of 20 years onwards. That’s because we produce 1 per cent less collagen each year (so the skin retains less water); the surface cells (keratinocytes) tend to accumulate in clumps on the skin surface, leading to the appearance of dry flakes.
The fat cells underneath start to shrink and this leads to a reduction in water transferred from the blood into the upper skin layers.
Finally, from age 50 onwards the sebaceous (oil) glands start to shrink, leading to less oil in the skin. The areas of our skin with the smallest number of sebaceous glands are the most susceptible to this drying effect, namely the lower legs and hands.
So as we get older we want to try to preserve the natural oil in our skin. To try to combat dry skin conditions, moisturisers (‘emollients’) have been used for hundreds of years.
There are two main types of ingredients in an emollient: humectants, or water-holding ingredients, attract water from the depths of the skin. Humectants include urea, propylene glycol, glycerine and hydroxyl acids. The other type of ingredient, occlusives, creates an oily barrier at the skin surface, sealing in water and reducing evaporation — ingredients include paraffin, lanolin and mineral oils.
The most effective moisturisers contain humectants and occlusives. Different parts of our skin need different types of emollients.
Generally, it is recommended we avoid heavy, oily emollients on our face where clogging pores can lead to acne. Lower legs and feet/hands tend to be much drier than the rest of our skin and rich, oily emollients are needed.
Look for an emollient that contains an oil, such as a coconut or cocoa butter or paraffin, plus one of the humectants listed above.
TRUTH ABOUT STRETCH MARKS
Your risk of stretch marks is greater if there is a family history, if you’re overweight before pregnancy or have a large baby. (And if you have stretch marks, you’re also more likely to experience a ‘tear’ during childbirth.)
But can you prevent them? Sadly, the short answer, research shows, is no — there is no strong, reliable evidence that the ‘standard’ remedies such as topical cream, bitter almond oil, olive oil and cocoa oil can prevent or reduce their severity. These might make your skin feel soft, but they won’t stop you getting stretch marks.
SUNBURN VERSUS VITAMIN D
Avoiding sunburn is clearly very important, but there’s no doubt that the sun is also important for health: most of us know that vitamin D is vital for our bones and immune systems — and that it’s made in the skin when it’s exposed to sunlight. But how much skin do you need to expose and for how long? The general consensus is that our bodies need around 20-25 mcg of vitamin D a day — as you might expect, how much sun exposure this requires depends on the intensity of the sunlight, the cloud cover and your skin type.
And now scientists at the Norwegian Institute for Air Research have devised a calculator that will take all these factors into account and then estimate what you need. To give you an idea, here is an example based on London as to what different skin types would need on alternate days at different times of the year:
Blond Caucasian: April 1: eight minutes; August 1: five minutes; December 1: two hours, 20 mins.
Mediterranean: April 1: 13 minutes; August 1: seven minutes; December 1: four hours, eight mins.
Black: April 1: 44 minutes; August 1: 24 minutes; December 1: more than 24 hours.
Because the exposure needed in the sunniest seasons to get vitamin D is so short, there is no risk of sunburn. It’s also worth pointing out that in the winter in London we would all have a lot of difficulty in making sufficient vitamin D in our skin from the sun.
Luckily, in the winter we can usually rely on our vitamin D stores to tide us over until the spring. We can also get additional vitamin D from our diet. Vitamin D is oil soluble which means you need to eat fat to absorb it (bear this in mind if you are on a low-fat diet).
Foods naturally high (or artificially fortified) in vitamin D include oily fish, mushrooms, cheese, eggs, tofu, fortified cereals, fortified milk, soya and almond milk.
To work out how much sun exposure you need where you live, go to fast.
Do supplements for nails work?
Fingernails grow about twice as quickly as toenails, and the longer the finger (or toe) the more rapid the growth of the nail.
So our middle fingernail grows faster than our thumb/little fingernails. The average rate of growth of most fingernails is 4.8 mm/month and toenails 2mm/month.
If you have ever damaged your nail, by hitting it with a hammer for example, you will notice it takes months for the blood patch in the nail to ‘grow out’.
On average it takes nine months to grow a new fingernail and 12 to 14 months to grow a new toenail.
If we are seriously ill for a few weeks or more, our nails can temporarily stop growing and then, when we recover, they start growing again.
The episode of nail growth arrest is subsequently seen as a horizontal line called Beau’s line — a bit like rings on a tree trunk showing good or bad growing seasons.
Similarly, a white spot or streak on your nail is not due to calcium deficiency, but are caused by little knocks or bumps.
Can taking supplements improve the texture and strength of your nails? In fact, there is little evidence it can, but there is some evidence that rubbing oily moisturisers on to dry nails can enhance their hydration and reduce brittleness.
Fats and oils made up of glycolic and stearic acids, such as coconut oil, help to keep nails water resistant, maintaining the water level of nails at around 18 per cent.
If the water content of our nails drops below 16 per cent, nails can become brittle.
