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The effect of a low glycemic load diet on acne vulgaris and the fatty acid composition of skin surface triglycerides.

The effect of a low glycemic load diet on acne vulgaris and the fatty acid composition of skin surface triglycerides Smith RN, Braue A, Varigos GA and Mann NJ J Dermatol Sci, 2008, 50, 14-52

The debate about whether diet influences acne pathogenesis has continued for many decades. Diet could influence the hormonal status of the body, as well as influence the types of lipids comprising the sebum. Sebum and hormones are both strongly implicated in the occurrence of acne, with the disease appearing at the onset of puberty as the circulating level of testosterone increases. Concomitant with this is an increase in sebum production and it has long been known that the amount of sebum produced is strongly correlated with the severity of acne.

Glycaemic load is a measure of the effect of food on the blood glucose levels as influenced by insulin after eating a specific food. Thus a diet that is rich in low-glycaemic index foods is regarded as a healthier choice as this would provide longer lasting constant blood sugar levels. This study examined whether such a diet was also beneficial for acne.

Male subjects, a total of 54 participants between the ages of 15 and 25 years, were followed for 12 weeks. The subjects were randomly assigned to groups having either a low-glycaemic index diet or a carbohydrate-rich, high-glycaemic index diet. The low-glycaemic index foods were steered towards more protein and wholegrain pasta, bread and fruits while the control group was provided with carbohydrate-dense foods and not given any information about the diet. Acne was assessed by a qualified grader and samples of sebum were obtained using the Sebutape. A full data set of both acne assessment and sebum samples was only obtained from 31 subjects.

The data showed that after 12 weeks of a low-glycaemic index diet, acne was significantly improved. The follicular sebum outflow as measured in the Sebutapes did not differ between the two groups of subjects, although the group on a low-glycaemic index reported less oily skin at week 12. Additionally, the composition of the skin surface triglycerides changed as measured by an increase in the ratio of 16:0/16:1 fatty acids and an increase in the ratio of saturated fatty acids:monounsaturated fatty acids. These data suggest that desaturation of sebaceous lipids may play a role in acne development.

Therefore, it would appear that the amount of saturation of fatty acids and triglycerides in sebum, or as applied to the skin, has critical roles in skin function. As the proportion of monounsaturated fatty acids in sebum increases, there appears to be an increase in sebum outflow to the surface of the skin. Addition of the monounsaturated fatty acids, oleic and palmitoleic, can induce scaly skin, abnormal keratinisation and epidermal hyperplasia. In contrast, triglycerides and saturated fatty acids (for example palmitic and stearic acid) have no effect on skin morphology. It is speculated that monounsaturated fatty acids interfere with the calcium dynamics of follicular keratinocytes and the intercellular lipid bilayer. This paper does not discuss what the effect of the low glycaemic index diet might be on follicular bacteria and the interplay of follicular bacteria with the other pathogenic features of acne. Increased activity of follicular bacteria is a key causative factor in acne, and bacterial activity is influenced by the nutrients provided in the sebum. A change in the availability of certain key fatty acids could have an effect on the level of follicular bacterial activity, which may explain the reduction in acne reported in this research. Furthermore, it is also interesting that desaturation of fatty acids appears to have a negative effect on the skin while biological data from studying the causes of coronary heart disease advocate the importance of unsaturated dietary fatty acids. The authors of this paper suggest that the low-glycaemic index diet may work indirectly on the sebaceous gland by influencing hormone levels, specifically reducing testosterone bioavailability and dehydroepiandrosterone sulphate concentrations, which may be explained by the insulin-lowering effect of these diets.
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Author:Knaggs, H.E.
Publication:Clinical Dermatology
Date:Mar 1, 2008
Words:668
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