How Does High Glycemic Diet Affects Acne vulgaris?

Key Points

• Acne is the result of increased keratinization, sebum production, and inflammation
• A high glycemic diet can increase the production of insulin and insulin-like growth factor
• Elevated levels of insulin and insulin-like growth factor may cause or exacerbate acne
• Effects of high Glycemic Diet on Acne / Effects of Glycemic Index of Carbohydrates on Acne vulgaris

Pathogenesis of Acne

Acne Vulgaris is one of the most prevalent inflammatory skin conditions affecting many teenagers and adults.¹ Pathogenesis of acne is multi-factorial, including follicular hyperkeratinization, hypersensitivity reaction of the sebaceous glands to androgens, and inflammation which in part is driven by Cutibacterium acne (formerly Propionibacterium acnes).²

Acne is more common in individuals going through puberty due to the influence of hormones, most notably androgens. Androgens stimulate sebum (oil) production and hyperproliferation of the follicular epidermis, resulting in the entrapment of sebum within the skin which can form comedones (often called whiteheads or blackheads).² When the clogged follicles rupture, pro-inflammaotry chemicals are released into the dermis resulting in inflammatory lesions.

Recent studies suggest that diets high in complex carbohydrates and simple sugar content affect serum insulin and insulin-like growth factor-1 levels, both of which have been shown to promote overproduction of androgens and subsequent development of acne.

The Glycemic Index

Carbohydrates are an essential component of our diet, but not all carbohydrates are equal. The Glycemic Index (GI) is a physiological assessment of carbohydrates in foods based on how they affect blood glucose levels.³ 

Carbohydrates can be ranked on a scale of low, medium, or high glycemic index (Table 1). Foods with a low GI are more slowly digested and absorbed, resulting in a steady and slower rise in blood sugar therefore leading to less insulin production. On the other hand, foods with a high glycemic index release glucose rapidly, resulting in a spike of blood sugar and insulin. For this reason, carbohydrates with a low GI are preferred for a healthy diet.

The glycemic index classification of foods has been used to assess prevention and treatment strategies for diseases where glycemic control is necessary, such as diabetes. Recent studies have shown that foods with a high GI may also contribute to acne pathogenesis and have highlighted that acne patients may benefit from glycemic control.⁵

Hyperinsulinemia and Insulin-Like Growth Factor

Diets with a high glycemic index can lead to hyperinsulinemia. Elevated serum insulin can stimulate the production of androgens and subsequently, sebum production.⁵ Sebum, or oil, is one of the main pathophysiological hallmarks of acne formation and exacerbation.

In addition to overproducing sebum, elevated insulin levels have also been shown to impact levels of circulating insulin-like growth factor (IGF-1) and insulin-growth factor binding protein (IGFBP-3). Under physiological conditions, IGF-1 is responsible for keratinocyte proliferation and IGFBP-3 stimulates apoptosis (programmed cell death).⁵ The homeostatic balance between IGF-1 and IGFBP-3 is disrupted during a state of hyperinsulinemia, leading to a predominance of IGF-1 resulting in increased keratinocyte proliferation, another major contributing factor to acne.^5,6

In fact, a study investigating the relationship between acne and a high glycemic diet found that acne patients had higher serum IGF-1 levels and lower serum IGFBP-3 levels compared to patients who did not consume a diet rich in glycemic-dense foods.^5,6

As IGF-1 increases it also influences the production of androgens, growth hormone, and glucocorticoids which can promote comedogenesis.⁵ Along with overproducing sebum, androgens may also increase endogenous levels of IGF-1 in the blood which subsequently produces more androgens, creating a vicious cycle of sebum production and therefore acne.

Conversely, studies have found that low glycemic diets are associated with a decrease in androgens and therefore acne.⁷ Those who maintain a low glycemic diet have lower body weights and consume foods rich in polyunsaturated fats and fiber as well as foods lower in saturated fat. This diet may have an impact on inflammation and hormones affecting the skin.⁷

Cultural Variations and Acne

Several studies have shown that non-industrialized cultures have lower rates of acne compared to Western populations, suggesting that diet may play a pivotal role in the pathogenesis of acne.

To analyze the effects of diet and acne, a study was conducted comparing two non-Westernized cultures, the Kitavan Islanders of Papua New Guinea and the Aché hunter-gatherers of Paraguay. Among approximately 1300 subjects within both groups, no cases of acne were reported. After analyzing the diets of both populations, their diets were considered within the low glycemic profile and devoid of Western refined foods such as cookies, breads, and chips. The Kitavan’s diet consisted of tubers, fruits, fish, and coconuts, with minimal dairy products, coffee, alcohol, sugar, salt, and oils. Similarly, the Aché community consumed locally cultivated foods, wild game, forest products, and minimal Western foods, such as pasta, flour, sugar, yerba tea, and bread.⁸

Similarly, in 1971 an epidemiologic study found that the native Inuit populations living in Northern Canada for almost 30 years had no reports of acne until the population was introduced to Western food products such as soda, beef, dairy, and processed foods.⁵

Researchers suggested that a low glycemic diet may be the reason behind the lack of acne noted in these populations. However, the absence of acne may also be conditioned by genetic and environmental factors.

Key Takeaways

• Diets rich in complex carbohydrates promote insulin production and subsequent elevation of androgens and sebum
• High glycemic foods can create an imbalance of IGF-1 and IGFBP-3 leading to increased sebum production and keratinocyte proliferation
• Cultures that do not regularly consume Westernized food products have lower incidence of acne compared to Western cultures