Spot the culprit: How milk can trigger acne - Independent Online Edition > Health
Spot the culprit: How milk can trigger acne
For decades scientists have searched for the causes of acne. Now a study has identified one of the key triggers: milk.
[...]
But why should milk, such an essential bone-building nutrient, be bad for our skin? Willett believes it's because of the hormones in the milk, and Danby has taken this argument a step further. What most dermatologists usually agree on is that the male hormone testosterone (also found in women), changes to dihydrotestosterone (DHT) in the sebaceous glands, the oil-producing glands in the skin. Acne is produced when the hormone causes too many of the cells that line the duct of the gland to be produced too quickly. Unable to separate from each other, they stick together and form a plug in the pore - the first visible sign of acne.
Of course, everyone will respond differently to hormones. As Danby says: "The ability to develop acne is partly genetic and partly the result of hormone exposure. I tell my female patients that genetics are the key to the fact that Paris Hilton has lots of money and no zits and my patients have lots of zits and no money. It is all genetics."
The milk most of us drink is produced by cows for their calves. To ensure maximum milk yields cows are inseminated days after giving birth to their calves, which are taken away. A dairy cow will spend most of its life being milked and being pregnant at the same time.
So milk is full of hormones: not only ones intended to help the calf grow, but also those produced by the placenta to aid the cow's pregnancy. They include DHT, and other hormones that are the pre-cursors to DHT. In other words, the hormones teenagers naturally produce are plentiful in milk. It of course contains other growth-enhancing hormones too - as Danby says: "Milk is, after all, specifically designed to make things grow."
Another worrying hormone, as far as acne is concerned, is IGF-1. This "growth factor" peaks at age 15 in girls and 18 in boys, coinciding with peak acne levels. IGF-1 is thought to works with testosterone and DHT to cause acne. IGF-1 is present in cows' milk anyway, but levels rise by 10 per cent when cows are given injections of recombinant bovine growth hormone (rBGH) to increase milk yield. Drinking organic milk is not a solution because the cows are still pregnant while lactating, so they have the same hormones in their milk as non-organic cows.
Danby's solution is to eliminate dairy from the diet - after all, he says, the Perricone diet is practically dairy-free. Nicholas Perricone, an American dermatologist who has launched a range of skin products, has also developed a skin-food diet based on eating large amounts of wild salmon.
However, Perricone's London-based nutritionist, Christopher Lee, disagrees with Danby: "A diet high in sugars and saturated fats is rich in free-radical-causing agents, which will exacerbate acne. But acne is triggered by hormones and is not caused by diet."
Saturated fats may play a role, but the Harvard Nurses study found that acne was most closely linked to skimmed milk. The researchers hypothesise that it is not the fat that is the problem, but the hormones, which may be altered. For instance, to give skimmed milk a creamier texture, whey is often added, and the protein in whey can make other hormones more reactive.
The Dairy Council isn't convinced, saying the study is flawed because, first, it asked participants to remember what they ate a decade ago and, second, it shows a link between milk and acne, which is not the same as proving that milk causes acne.
[...]
Danby agrees with the Dairy Council that the link between acne and milk is unproven: "My dermatological colleagues insist, with justification, on a full double-blind randomised controlled trial. But so far it has been impossible to arrange such a trial. Double-blinding dairy intake is essentially impossible because we have no hormone-free dairy we could feed people as a 'placebo'."
However, in defence of his dairy-free stance, he adds: "Objectively, human consumption of large volumes of another species' milk, especially when that milk comes mainly from pregnant cows during the human's normally post-weaned years, is essentially unnatural."
Spot the culprit: How milk can trigger acne
For decades scientists have searched for the causes of acne. Now a study has identified one of the key triggers: milk.
[...]
But why should milk, such an essential bone-building nutrient, be bad for our skin? Willett believes it's because of the hormones in the milk, and Danby has taken this argument a step further. What most dermatologists usually agree on is that the male hormone testosterone (also found in women), changes to dihydrotestosterone (DHT) in the sebaceous glands, the oil-producing glands in the skin. Acne is produced when the hormone causes too many of the cells that line the duct of the gland to be produced too quickly. Unable to separate from each other, they stick together and form a plug in the pore - the first visible sign of acne.
Of course, everyone will respond differently to hormones. As Danby says: "The ability to develop acne is partly genetic and partly the result of hormone exposure. I tell my female patients that genetics are the key to the fact that Paris Hilton has lots of money and no zits and my patients have lots of zits and no money. It is all genetics."
The milk most of us drink is produced by cows for their calves. To ensure maximum milk yields cows are inseminated days after giving birth to their calves, which are taken away. A dairy cow will spend most of its life being milked and being pregnant at the same time.
So milk is full of hormones: not only ones intended to help the calf grow, but also those produced by the placenta to aid the cow's pregnancy. They include DHT, and other hormones that are the pre-cursors to DHT. In other words, the hormones teenagers naturally produce are plentiful in milk. It of course contains other growth-enhancing hormones too - as Danby says: "Milk is, after all, specifically designed to make things grow."
Another worrying hormone, as far as acne is concerned, is IGF-1. This "growth factor" peaks at age 15 in girls and 18 in boys, coinciding with peak acne levels. IGF-1 is thought to works with testosterone and DHT to cause acne. IGF-1 is present in cows' milk anyway, but levels rise by 10 per cent when cows are given injections of recombinant bovine growth hormone (rBGH) to increase milk yield. Drinking organic milk is not a solution because the cows are still pregnant while lactating, so they have the same hormones in their milk as non-organic cows.
Danby's solution is to eliminate dairy from the diet - after all, he says, the Perricone diet is practically dairy-free. Nicholas Perricone, an American dermatologist who has launched a range of skin products, has also developed a skin-food diet based on eating large amounts of wild salmon.
However, Perricone's London-based nutritionist, Christopher Lee, disagrees with Danby: "A diet high in sugars and saturated fats is rich in free-radical-causing agents, which will exacerbate acne. But acne is triggered by hormones and is not caused by diet."
Saturated fats may play a role, but the Harvard Nurses study found that acne was most closely linked to skimmed milk. The researchers hypothesise that it is not the fat that is the problem, but the hormones, which may be altered. For instance, to give skimmed milk a creamier texture, whey is often added, and the protein in whey can make other hormones more reactive.
The Dairy Council isn't convinced, saying the study is flawed because, first, it asked participants to remember what they ate a decade ago and, second, it shows a link between milk and acne, which is not the same as proving that milk causes acne.
[...]
Danby agrees with the Dairy Council that the link between acne and milk is unproven: "My dermatological colleagues insist, with justification, on a full double-blind randomised controlled trial. But so far it has been impossible to arrange such a trial. Double-blinding dairy intake is essentially impossible because we have no hormone-free dairy we could feed people as a 'placebo'."
However, in defence of his dairy-free stance, he adds: "Objectively, human consumption of large volumes of another species' milk, especially when that milk comes mainly from pregnant cows during the human's normally post-weaned years, is essentially unnatural."
Comments