Your questions answered

Welcome to the new questions answered section of our website.

Each week you will find answers to one or more questions which were submitted to the treatment survey. These questions have not qualified for the next round for a number of reasons:

  • We already know the answers
  • They aren't about acne treatments or aren't answerable by new treatment related research.
  • They weren't amongst the most commonly asked questions and so don't appear on the shortlist for voting.

It has been challenging to provide adequate answers to some of the questions and we have learnt a lot from this part of the process. In the coming weeks, we hope invited experts will answer some of the more difficult questions and we do hope you will find these answers interesting and will benefit from them!

If you miss any of the questions and answers from previous weeks, you can find them all in the Media Centre of this website.

Diet and acne - what you should do if you think what you eat affects your skin

The possibility of treating acne through diet was one of the most common topics amongst the questions submitted to our survey. It seems most of you have heard that there might be a link between nutrition and acne but aren't certain whether or how it might affect you personally. Some of you were absolutely adamant that food has no effect on your skin, others were equally convinced that diet was having a huge effect on skin greasiness and spottiness. Some of you told us you had modified your diet successfully without professional help, but most of you had no idea how to start working out whether things you were eating were affecting your skin. Many of you asked what doctors should be telling you about food and acne and where you might go to get reliable dietary advice.

The first thing to say is that the link between diet and acne is very difficult to unravel. What we eat is just one of many lifestyle factors that may affect acne severity. The emerging story from ongoing research suggests that typical Western diets make acne worse or may even predispose to acne. The three key aspects of Western diets that are under the most scrutiny are:

  • Consumption of milk (especially skimmed milk) and dairy products,
  • Consumption of carbohydrates with a high glycemic index and foods with a high glycemic load,
  • Failure to eat sufficient amounts of foods that may protect against acne such as oily fish

Many of you will be aware that Western diets are being blamed for all sorts of conditions that are increasing in severity, things like heart disease and type II diabetes, and not just acne. It isn't simply a matter of what we eat but also how much we consume compared to how much we need.

The Glycemic Index (GI) is a ranking of carbohydrate-containing foods based on how quickly and how much blood glucose levels rise after eating them. Slowly absorbed carbohydrates have a low GI rating and don't cause sharp rises in blood glucose levels. A related measure, the Glycemic Load (GL), is calculated by multiplying the glycemic index of the food in question by the carbohydrate content of a typical portion or serving. This is a more helpful measure as it takes into account the amount of carbohydrate being consumed. Interestingly, milk has a low GI but induces a sharp rise in serum insulin, the hormone that regulates glucose metabolism. It also contains lots of bioactive substances (hormones, growth factors, fatty acids) that might affect acne.

Foods that are supposedly bad for people with acne-prone skin are thought to (a) increase the levels of hormones (insulin and insulin-related growth factor 1) that increase sebum production and/or (b) alter the composition of sebum so that it is less likely to cause blockage of the duct or inflammation. However, evidence that they do either of these things is sparse. Foods such as oily fish that are supposedly protective against acne have been postulated to make skin produce less sebum or better sebum and also to boost or alter the immune response making inflammation less likely.

Doctors are in a difficult position at the moment because the evidence of a link between any foods and acne is not strong enough to base dietary advice upon. Some experts are convinced of a link, others are not. If there is a link, it is almost certainly not a simple one. The complexity of the Western diet makes studying the role of diet in acne very difficult. At the moment, there is insufficient evidence about the contribution of dietary factors in acne for the NHS to make any recommendations to doctors. However, your doctor should be prepared to talk to you about the possible role of dietary factors. He or she will not recommend or advise you to go on a special diet.

What effects do water and alcohol consumption have on acne?

The simple answer is we don't know. No study has looked at the effect of drinking lots of water on acne severity. However we do know that water retention, as occurs in women just before a period, makes acne worse, possibly by shrinking the size of pores. There is no known scientific reason why drinking large volumes of water should help acne.

A few epidemiological studies from overseas have looked to see if alcohol consumption affects acne severity. The results are contradictory. There are no studies on other types of drink except milk (see above).

Acne and body weight or body mass index - is there an association?

You'd think we know the answer to this but we don't! Surprisingly few studies have looked at the link between body weight or body mass index (BMI) and acne. In a subset of women with polycystic ovary syndrome (PCOS), acne can be associated with increased BMI but this is not true of all women with PCOS or for women generally. There are no data for adolescents generally or for males. One study suggests children under 11 with acne had slightly higher BMI values than those without acne but this might be simply due to more advanced puberty in the acne group. In other words, there is no evidence yet to suggest that calorie intake as opposed to type of diet affects acne severity.

Can I work out for myself if my diet is making my spots worse?

Until we understand more about diet and acne, we don't know if it is possible to make simple dietary changes that will have a dramatic effect on the skin. The few dietary intervention studies that have been completed show small effects not big ones. This is probably because it is necessary to change lots of dietary factors simultaneously whereas clinical trials look at the effect of changing just one. Findings from epidemiological studies also show small effects of separate dietary variables; their cumulative effects might be much greater. Therefore, if you decide to ‘experiment' by eliminating one food at a time, you are very unlikely to see much benefit. Without expert advice, most of us cannot reliably explore the effect of the type of carbohydrate we eat on acne severity but we can do something about the amount. If you know you eat lots of white bread and chips for example, then it makes sense to eat less, not just for your acne but also for your health more generally. Similarly, if you know your diet is heavy on dairy products, you can try cutting down on the amount. Never remove whole food groups from your diet. If you are a healthy weight, don't cut calories, just change the sorts of carbohydrate you eat. Adding foods that may protect against acne to an unhealthy diet almost certainly won't help much but replacing unhealthy ones with healthier alternatives might. There are plenty of reliable sources of information about healthy foods. See, for example, http://www.nhs.uk/LiveWell/healthy-eating/Pages/Healthyeating.aspx

The best advice anyone can give at the present time is to eat a balanced diet and cut down the number of times you exceed the recommended daily calorie intake for your age. If you know your diet is poor and want to switch to a better one, don't expect an instant result. It may take several months to see a change in your skin. We don't know if diet affects some people with acne more than others, but it is possible that some individuals may see big improvements whereas others see no or very little change. It may depend on how our bodies process the food we eat and that in turn depends on the levels of many different hormones.

Is there a role for dietary supplements in managing acne?

We know even less about the role of dietary supplements in acne than we do about foods. There are lots of companies willing to sell you all kinds of supplement to protect against acne but there is precious little evidence that any dietary supplements either prevent acne or reduce acne severity. A very small recent trial has shown that omega-3 fatty acids and gamma-linolenic acid improved acne after 10 weeks treatment compared to an untreated control group. This study needs repeating in much larger numbers of people before any conclusions regarding benefit can be drawn.

Whilst, we are fairly sure that acne is not normally associated with any dietary deficiencies, there has been a lot of recent publicity about the increasing number of young people in Europe who have low levels of vitamin D. Make sure you aren't one of them as vitamin D is vital for many reasons not just keeping skin and bones healthy.

Did the role of diet in acne make the TOP TEN?

Yes, and no. The people who attended the workshop agreed diet was important but recognised it was one of many lifestyle factors that might affect acne. In consequence they combined one of the two diet questions on the shortlist into the following question which ranked number 6:

Which lifestyle factors affect acne susceptibility or acne severity the most and could diet be one of them?

Diet is already a hot topic in acne research and there are several ongoing studies investigating the role of diet and dietary supplements in more detail. One of the most interesting is a controlled clinical trial looking at the effect of a low glycemic load AND milk free diet on acne severity. The results are due next year. Three more trials are looking at the effects of omega-3 fatty acid supplementation. Two of these are complete and the results should be published soon.

Summary

  • There may be an association between diet and acne but it is almost certainly complex and presently poorly understood.
  • Some foods may, in susceptible individuals, make acne worse and some may protect against acne. The foods most strongly linked to acne are carbohydrates like white bread that trigger rapid rises in blood glucose, milk (especially skimmed milk) and dairy products. Foods like oily fish, which contain large amounts of omega-3 fatty acids, might protect against acne but more data are needed.
  • It is sensible to have a healthy balanced diet and not over-eat. Never make drastic changes to your diet without expert help.
  • Doctors cannot give specific dietary advice until the evidence is more robust but should be willing to talk to you about your diet.
  • There is no evidence that drinking lots of water improves acne.
  • Any benefit of dietary supplements in preventing or treating acne is as yet unproven.