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:
- Increased secretion of skin oil (sebum) under the influence of the androgen hormone dihydrotestosterone (DHT)
- 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).
- Colonization 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 realize 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.
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). 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. 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 glycemic diet. A high glycemic 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 glycemic diet stimulates proliferation of keratinocytes, which is one of the factors involved in acne development iii.
- A high GI diet also affects testosterone metabolism
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.
Similar results were found in a group of over 6000 adolescent girls.
Red meat contains hormone-like substances that may affect DHT levels in body tissues.
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.
Although it is often claimed that chocolate makes acne worse, there is actually no evidence that this is the case. 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).
BUT no benefits are likely with white chocolate: it contains few antioxidants and lots of fat and sugar.
It is becoming increasingly clear that poor nutrition can make symptoms of acne worse. At least one dermatologist now recommends a ‘no dairy, low glycemic’ dietary approach to help improve symptoms of acne.