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Monday’s medical myth: chocolate causes acne

Outbreaks of pimples, blackheads and cysts are a cause of enormous anxiety and embarrassment among teens and young adults. If you’re part of the 20% of Australians who have experienced severe acne, you’ve…

There’s no evidence to show chocolate causes acne but milk may play a role. anjuli ayer

Outbreaks of pimples, blackheads and cysts are a cause of enormous anxiety and embarrassment among teens and young adults. If you’re part of the 20% of Australians who have experienced severe acne, you’ve probably tried a raft of treatments and preventive measures. But does giving up chocolate help?

It’s unclear where or how this myth arose, but researchers tested the link three times from 1965 to 1971, suggesting it must have been a commonly held belief at least 40 years ago. All three studies came up with the answer: chocolate doesn’t exacerbate acne.

But by today’s standards, the investigations were all of a poor scientific standard. The original study, conducted in 1965, contained just eight participants.

The next study, published in Journal of the American Medical Association in 1969, had 65 participants, but the results were confounded by the use of two different groups of subjects: 60 adolescents (14 girls) and 35 young adult male prisoners of an unspecified age. The researchers didn’t account for the effects of gender, age, puberty, menstrual cycles, stress, smoking, lifestyle, background dietary intake or medical conditions affecting the skin.

The 1971 study, published in the journal American Family Physician, evaluated the effects of chocolate, milk, roasted peanuts and cola on acne in 27 students, but it failed to report their age and only followed them for one week. Also, it didn’t address all potential confounders and failed to report significant acne outbreaks during or immediately after the study period.

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Several detailed critiques of these studies' shortcomings have since been published. But the chocolate and acne myth has remained controversial and unchallenged since.

A recent study of YouTube videos found more than 85% of clips with keywords acne, “acne diet” and acne food" supported the belief that diet has a moderate association with acne.

So why does the myth that chocolate causes acne continue to circulate?

Perhaps the fault lies with us as researchers as the protagonists of evidence-based practice. We have failed to subject this chocolate myth to the rigours of a randomised control trial (RCT), despite the fact that almost all people aged 15 to 17 years experience some degree of acne. We need a decent RCT so we can know once and for all whether to unleash our teenagers, and ourselves, in the confectionery aisle at the supermarket.

Food and acne

Recent evidence suggests it may be time to expand our investigation of chocolate and acne and focus on milk consumption and the glycemic index (GI).

Milk and its products, including pasteurised milk, yoghurt, ice cream and cottage cheese, contain an array of naturally occurring ingredients that promote growth. The whey protein of dairy products, with the exception of cheese, leads to an increased release of insulin. And the casein protein in dairy products leads to an increase in levels of insulin-like growth factor (IGF).

Surprisingly, drinking milk raises blood insulin levels to a greater degree than predicted, based solely on its lactose content (the carbohydrate found in milk). Although the biochemical pathways are complex, in simple terms, this can lead to a worsening of acne.

This same reaction does not occur after eating cheese.

If you have acne, consider reducing your milk intake. But cheese is unlikely to prompt an outbreak. m.gifford

Glycemic Index and Glycemic Load

Diets with a high glycemic index (GI) or glycemic load (GL) trigger a higher insulin response. This is because high-GI foods contain carbohydrate in a form that is quickly digested and absorbed into the blood stream, sending a message to the pancreas to secrete insulin.

This high level of insulin, in turn, increases IGF, potentially exacerbating acne. The insulin then sets out to clear the glucose from the blood.

So can a high GL diet, with more high-GI foods, help manage acne?

This was tested in a 2007 randomised control trial. The researchers asked 43 males aged 18 years to follow either a low-GL or a high-GL diet for 12 weeks. Meanwhile, the severity of their acne was assessed by dermatologists who were blinded to the dietary intervention aspects of the study.

The low-GL groups were instructed to swap some high-GI foods for others higher in protein, such as lean meat, chicken, or fish, and to favour lower-GI foods such as, wholegrain bread, pasta, and fruits. The low-GL diet aimed for 25% energy from protein, 45% from low-GI carbohydrates, and 30% energy from fats. The high-GL group was encouraged to follow a high-carbohydrate diet.

Interestingly, those following the low-GL diet saw their acne improve, along with their insulin sensitivity. They also lost weight. It’s important to note, however, that this work has not been repeated by other researches at this stage.

What to do if you suffer from acne

Acne commonly persists into adulthood, with almost two-thirds of adults in their 20s and 43% in their 30s experiencing the condition. No matter what your age, you can get help from your GP who may need to refer you to a dermatologist.

When it comes to food, more good quality research studies are needed to assess the impact of dietary manipulations. But along with medical treatment, there are some dietary strategies worth trying:

  1. Reduce your intake of high GI carbohydrate foods, such as potatoes, doughnuts, pancakes, sweetened breakfast cereal, and white bread. Swap high GI for lower GI choices such as apples, bananas, carrots, corn, muesli, mixed grain bread, pasta, porridge, tomato soup, sweet potato.

  2. Be more active to improve insulin sensitivity; go for a short walk after eating to help reduce blood sugars and moderate insulin levels.

  3. Reduce your milk (but not cheese) intake. To achieve peak bone mass you will need to take a daily calcium supplement.

  4. If you’re overweight, try and reduce your weight, even by a few kilograms.

Join the conversation

27 Comments sorted by

  1. Sue Ieraci

    Public hospital clinician

    Surely the chocolate-and-acne argument must have a moral origin - something that tastes so good must do something bad to you!

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  2. Dale Bloom

    Analyst

    Several links seem to be broken.

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  3. 6minutes medical

    logged in via Twitter

    I'm a great believer in EBM, but the fact is that I get zits on the rare occasions when I eat chocolate, and never at any other time. Maybe that's an n=1 trial. And as for the GI diet evidence - I have yet to see anyone explain why the Chinese, who consume large amounts of high-GI white rice, have such low levels of diabetes (and acne)?

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    1. Steve Brown

      logged in via email @yahoo.com.au

      In reply to 6minutes medical

      "I have yet to see anyone explain why the Chinese, who consume large amounts of high-GI white rice, have such low levels of diabetes"

      Because the gylcemic index, as a theory of disease, is most likely bogus.

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  4. Rosemary Stanton

    Nutritionist & Visiting Fellow at University of New South Wales

    The preliminary GI/GL study quoted used just 43boys (aged 18) with only half of them following a better diet. These are very small numbers and the confidence intervals in that study so wide that any results are dubious at best. Not sure how these poor statistics got past the reviewers for publication.

    Also, swapping foods such as doughnuts, pancakes, sweetened breakfast cereal, and white bread with apples, bananas, carrots, corn, muesli, mixed grain bread, pasta, porridge and sweet potato will change many things besides GI. The substituted foods are high in dietary fibre and contribute many more nutrients. It's premature to sheet the very slight (and statistically invalid) results from this study to GI/GL.

    I agree we need a good study to see if cutting out junk food helps reduce acne. Why have such studies not been done? Could potential funders be reluctant to support such research?

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    1. Steve Brown

      logged in via email @yahoo.com.au

      In reply to Rosemary Stanton

      "The substituted foods are high in dietary fibre and contribute many more nutrients."

      That certainly doesn't apply to wholegrains whose anti-nutrients only contribute to nutritional deficiencies.

      Given that most people remain untested for celiacs coupled with the more recent research showing gluten's adverse affect on the digestive systems of non-celiacs people it seems highly irresponsible for any dietician to be recommending them as a staple.

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    2. Steve Brown

      logged in via email @yahoo.com.au

      In reply to Rosemary Stanton

      Certainly:

      "Apparently the human organism is still largely vulnerable
      to the toxic effects of this protein complex, particularly
      due to a lack of adequate adaptation of the
      gastrointestinal and immunological responses"

      All individuals, even those with a low degree risk, are therefore susceptible to some form of gluten reaction during their life span."

      http://www.biomedcentral.com/content/pdf/1741-7015-10-13.pdf
      http://annals.org/article.aspx?volume=156&issue=4&page=309
      http://www.ncbi.nlm.nih.gov/pubmed/21224837

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    3. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Steve Brown

      Steve
      The article you quote on gluten aimed to cateorise different types of reactions to gluten. For coeliac disease - which si the one that we would be concerned about (because it leads to damage of the lining of the small intestine) is estimated to occur in 1 in 100 people, although many studies show a lower incidence.

      I presume you are not suggesting that the majority of the population should be tested for coeliac disease, although that may make the gastroenterologists very happy!

      On the…

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    4. Steve Brown

      logged in via email @yahoo.com.au

      In reply to Rosemary Stanton

      Regarding celiacs, I wasn't suggesting there should be a widespread testing of the population, merely that it makes little sense to me to recommend gluten grains in the regular diet seeing as celiacs folk often suffer poor health for years not knowing what is wrong with them until they are diagnosed. Couple that with the evidence showing an obvious adverse reactions to gluten in the wider population and it isn't hard to make a case for everybody going gluten free.

      I'll concede the point about…

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    5. Sue Ieraci

      Public hospital clinician

      In reply to Steve Brown

      Hmmmm...Rosemary Stanton, eminent nutritionist vs Steve, middle management - who to believe...?

      Steve - did you not think that Ms Stanton kept up with the literature in her area?

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    6. Steve Brown

      logged in via email @yahoo.com.au

      In reply to Sue Ieraci

      You don't do yourself many favors when you decide to argue your case using an appeal to authority (job title, qualification, experience, perceived prestige, reputation) rather than argue it on the data.

      Do I think Ms Stanton keeps up with the literature? It's difficult to know whether she is genuinely unaware of all of the research I've mentioned or if she just chooses to ignore it and read what agrees with her beliefs.

      Either way she hasn't addressed three quarters of what I've talked about. For what reason is unclear.

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    7. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Steve Brown

      Hi Steve

      I do try to keep up with all the literature and read a great deal more than you do. That enables me to see how you ignore material that doesn't suti your viewpoint and note that you are a good cherry picker. That all makes any reply a very long process.

      I also have a day job, a lot of involvement in various committees that involve a great deal of work, some urgent local commitments - and a family. I have just taken a few days off (it's school holidays) and returned late last night. I will try to get to your material as soon as I can.

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  5. Clare Collins

    Professor in Nutrition and Dietetics at University of Newcastle

    Rosemary

    It is astounding that a well designed RCT has not been done for such a prevalent condition. Perhaps it may not be seen as "important" enough, but I think more likely, that we have not sought funding at all.

    Sound like we agree though on the bottom line:-
    Eat more healthy food
    Make sure you intake is nutritionally adequate
    Move more
    Aim for a healthy weight
    Seek medical advice for severe acne.
    regards
    Clare

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  6. Thor May

    retired (PhD)

    Humans seem to have enough chemical variation that no study is going to catch it all for everyone. In my case, I had severe pimples until I was 38 y.o. . I accidentally found the culprit by using three spoonfuls of (tasteless) decaffeinated coffee. The effect was dramatic and I have avoided coffee ever since. End of pimples. Any kind of coffee does it, though some are worse than others. Apparently there are dozens of chemicals in coffee. No medico has ever shown the slightest interest in this coffee-reaction since I'm obviously non-human and come from Krypton.

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  7. Steve Brown

    logged in via email @yahoo.com.au

    I am pretty skeptical of the criticisms leveled at dairy, even it's implication in acne.

    The Masai, Somali and Samburu tribes all lived off nothing more than meat and milk and provide us with a pretty good (and extreme!) example of milk's effect on human health. The epidemiological research reported no widespread cases of acne amongst them when they were consuming their traditional diet, but acne was reported once they adopted a more western diet (bread, vegetable oils etc)

    Studies which document allergy to dairy are confounded by other variables, namely gluten grain and seed oil consumption. Both are implicated in immune system problems and an array of other deleterious health effects.

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  8. Clare Collins

    Professor in Nutrition and Dietetics at University of Newcastle

    In this meta-analysis of 7 prospective cohort studies in Asian and Western populations and that included 13,284 incident cases of type 2 diabetes from among 352,384 people with follow-ups from 4 to 22 years, the Chinese and Japanese populations had 3-4 serving of white rice/day compared to 1 or 2 in Western populations. The pooled relative risk (RR) of developing type 2 diabetes was 1.55 for the highest compared to the lowest category of intake of white rice in Asian populations. In the Western…

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    1. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Steve Brown

      I agree with you here Steve. China has exceptionally low rates of diabetes, although they are increasing as the diet becomes more westernised - and rice intake decreases. Of course, physical activity is also decreasing, and obesity is increasing and the population is living longer so these factors are also relevant.

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    2. Sue Ieraci

      Public hospital clinician

      In reply to Rosemary Stanton

      Rosemary - isn't the high/low GI difference really only an issue when you already HAVE diabetes, and are not secreting, or reacting to, insulin normally?

      I was not aware that the GI of a food could actually CAUSE diabetes. Can it?

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    3. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Sue Ieraci

      yes, Sue - you are correct. Gi is mainly important for those with diabetes. The GI of a food doesn't cause diabetes. Also GI is not the whole story. Plenty of junk foods have a low GI so it is important to look first at the nutritional value of a food and then its GI. A low GI doesn't change a junk food into anything other than a junk food.

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  9. Steve Brown

    logged in via email @yahoo.com.au

    I forgot to mention, for Rosemary and Clare who raised the absence of studies on acne, Loren Cordain (advocate of the paleo diet) has published research, the papers are available on his website. It's very interesting reading and clearly implicates acne as a disease of civilization:

    "Of 1200 Kitavan subjects examined (including 300 aged 15-25 years), no case of acne (grade 1 with multiple comedones or grades 2-4) was observed. Of 115 Aché subjects examined (including 15 aged 15-25 years) over 843 days, no case of active acne (grades 1-4) was observed."

    http://thepaleodiet.com/published-research

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    1. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Steve Brown

      However, there are many differences in the Kitavan subjects that could be relevant. A paleolithic diet is simply not possible today. Today's meat is nothing like wild meats. There is not enough fish in the world for high consumption of fish, especially wild caught fish. Almost everything else about our lifestyle is also different - housing, air pollution, urban lifestyles for most, less physical activity, longer lifespans.

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    2. Sue Ieraci

      Public hospital clinician

      In reply to Rosemary Stanton

      Why do we like to imagine that there is any sort of "natural" human diet?

      A human diet in ancient times was very much dependent on what part of the world you were it - and whether you were near the sea or water. Surely the ancient Innuit diet differs from the Masai, which differs from the highlands of New Guinea.

      There doesnt seem to be much point speculating about a generic human diet - it all depends on whether you are on a snowy mountain or in the tropics, whether your family has a good hunter or gatherer, whether you mastered agriculture, whether anything grows in winter - etc etc.

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  10. Kerri Worthington

    housekeeper

    My 10 year old daughter is already getting pimples on her pretty cheeks and I desperately hope for her sake it won't turn into full-blown acne. So I don't care much about the statistics of the less dairy-low GI diet -- it's good enough for me. It's eggs not weetbix for breakfast from now on. And I just sent her out for a post-lunch walk to stabilise her insulin levels :) It had better work!

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