Acne & Diet: Is There A Link?
Nearly 90% of us will be troubled by acne at some time in life; most frequently but not exclusively, in adolescence. Although it is widely claimed that acne is not linked with diet, intuitively it seems right that eating a healthy diet might improve the symptoms of acne. Researchers are now finding increasing evidence that nutrition can have a profound effect on skin health.
Oily Skin, Blackheads & Pimples
Oily skin, blackheads and the pimples that are symptomatic of acne are caused by:
1. Increased secretion of skin oil (sebum) under the influence of the androgen hormone, dihydrotestosterone (DHT)
2. Blockage of sebaceous gland oil ducts by skin cells (keratinocytes) that stick together rather than separating and being shed; this traps oil within the gland to form a blackhead (comedone).
3. Colonisation of black heads with the skin bacterium, Propionibacterium acnes; this triggers an inflammatory immune reaction with the development of papules, pustules and nodules.
Researchers are starting to realise that diet can influence all three of these factors: the production of DHT within skin oil glands, the ‘stickiness’ of keratinocytes, and the degree of inflammation that results.
Glycemic Load
Oily skin, blackheads and pimples are linked with increased sensitivity of skin sebaceous glands to dihydrotestosterone (DHT). The effects of DHT are stimulated by the substance called insulin-like growth factor (IGF-1). Levels of IGF-1 rise during puberty, typically around the age of 15 years in girls, and 18 years in boys i .
Acne is not just an adolescence problem: as many as 54% of women and 45% of men over the age of 25 show some degree of facial acne ii . Acne symptoms in later life are often linked with being overweight, and with increased production of insulin and IGF-1 as a result of a high glycaemic diet.
A high glycaemic diet is one that contains significant amounts of sugars and refined carbohydrates, and which causes rapid swings in blood glucose levels and insulin secretion.
• The increased secretion of insulin and IGF-1 that is associated with a high glycaemic diet stimulates proliferation of keratinocytes, which is one of the factors involved in acne development iii.
• A high GI diet also affects testosterone metabolism iv.
o A pilot trial involving 12 males with acne found that blood levels of insulin, IGF-1 and male hormones (androgens) were higher in those following a high GI diet v.
o When 43 males with acne followed either a low GI diet or a high GI for 12 weeks, the number of acne lesions decreased more in those on the low GI diet than in those on the high GI diet (an average of 25.5 less spots versus 12 less spots) vi.
Milk
Milk contains sugars such as lactose, plus growth factors and hormones that can increase insulin and androgen levels vii,viii,ix,x.
The effect of milk on the production or insulin and IGF-1 is three times greater than would be expected from its carbohydrate content alone.
Researchers who looked for a link between acne and the dairy intake of over 4200 boys found that those consuming more than 2 servings of milk per day were more likely to have acne than those consuming dairy products less than once a week xi .
Similar results were found in a group of over 6000 adolescent girls xii.
Meat
Red meat contains hormone-like substances that may affect DHT levels in body tissues xiii.
Omega-3/Omega-6 Balance
Omega-3 fatty acids (especially DHA and EPA found in oily fish) are converted in the body into substances (series 3 prostaglandins and series 5 leukotrienes) that reduce inflammation.
In contrast, most Omega-6 fatty acids (derived from vegetables oils such as sunflower, safflower and corn oils) are converted into substances that promote inflammation.
GLA (gammalinolenic acid found in evening primrose oil, for example), is one of the few Omega-6 fatty acids that has an anti-inflammatory action.
An imbalance between our intakes of Omega-3s and Omega-6s has been linked with worsening of symptoms in inflammatory diseases xiv such as asthma and rheumatoid arthritis, and may also play a role in acne symptoms xv.
Chocolate
Although it is often claimed that chocolate makes acne worse, there is actually no evidence that this is the case xvi.
In fact, dark chocolate containing at least 72% cocoa solids might be expected to improve symptoms as it is one of the richest dietary sources of anti-inflammatory antioxidants.
Dark chocolate provides an extraordinary 103,971 ORAC units per 100g - over 10 times more than is obtained from pomegranates (10,500 ORAC units) xvii.
BUT no benefits are likely with white chocolate: it contains few antioxidants and lots of fat and sugar.
Conclusion
It is becoming increasingly clear that poor nutrition can make symptoms of acne worse.
At least one dermatologist now recommends a ‘no dairy, low glycaemic’ dietary approach to help improve symptoms of acne.
More information is available at http://www.acnemilk.com/
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vi Smith RN et al. Am J Clin Nutr 86(1):107-15
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x Darling JA et al. J Endocrinol 1974;62:291-297
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xiii Cho E et al. Arch Intern Med 2006;166:2253-2259
xiv Simopoulos AP: J Am Coll Nutr 2002;21:495-505
xv Cordain L. Semin Cutan Med Surg 2005;24:84-91
xvi Spencer EH et al. Int J Dermatol 2009;48(4):339-347
xvii Wu X et al. J Agric Food Chem 2004;52(12):4026-37