Hormonal Acne: The Effects of Diet.

Acne is achronic inflammatory diseasethat presents itself through the emergence of spots on the face and/or body. The causes are multifactorial: genetic factors, hormonal imbalance, stress, intake of certain medications...

In the case of acne, we observe a hypersecretion of sebum (referred to as hyperseborrhea) at the level of the pilosebaceous follicles, along with a hyperkeratinisation. The sebum will clog the pores, which are the openings of the sebaceous glands on the skin's surface. This fat-rich environment will be conducive to the proliferation of the bacteria responsible for the onset of acne, Cutibacterium acnes (formerly Propionibacterium acnes), which primarily feeds on sebum. This bacteria secretes pro-inflammatory substances that cause inflammation and the formation of spots.

Acne is very often underhormonal influence. Indeed, hormones stimulate the activity of the sebaceous glands that produce sebum. This is the case during periods of hormonal upheaval such as adolescence or adulthood with menstrual cycles, pregnancy and menopause:

• Puberty : Acne is a condition that predominantly affects teenagers (around 80% of them) during puberty. This can be explained by the onset of sexual hormone secretion. Indeed, these sexual hormones stimulate the sebaceous glands which then overproduce sebum, thus promoting the appearance of acne.

• Menstrual Cycle : Acne can also affect adults, particularly women (around 25% of them), referred to ashormonal acne. In the first part of the menstrual cycle, the ovaries produce oestrogens, female sex hormones. In the second part of the cycle, the level of oestrogens decreases and that of progesterone increases following ovulation. Progesterone is the hormone that prepares for a potential pregnancy. If there is no fertilisation, the level of progesterone also decreases. Approximately 1 week before the onset of menstruation, testosterone, although in small amounts, reaches a level higher than feminising hormones. However, testosterone is an androgen hormone responsible for stimulating the sebaceous glands, thus causing the appearance of acne spots.

• Pregnancy : Pregnancy acne is caused by hormonal fluctuations during this period. Indeed, during pregnancy, the levels of progesterone and oestrogen skyrocket. These hormones can act on receptors at the sebaceous glands and stimulate sebum production. This overproduction of sebum results in the appearance of acne.

Note : Adult women are more affected by hormonal acne than men. Indeed, men's sexual hormone levels stabilise after puberty, whereas women's hormones fluctuate throughout their lives (menstrual cycle, pregnancy and menopause). Moreover, adult women's acne can be exacerbated by various factors including diet.

Many studies have focused on the link between acne and the glycaemic index of the diet. The glycaemic index of a food indicates its ability to increase the concentration of glucose in the blood. When a food has a high glycaemic index, the glucose level will quickly rise in the blood. In response, the pancreas will stimulate the secretion of insulin, which is a hypoglycaemic hormone.

Note : An hormone is referred to as hypoglycaemic when it reduces the level of sugar in the blood. Conversely, a hyperglycaemic hormone increases the level of sugar in the blood.

Among the foods with a high glycemic index, we can mention the white bread, potatoes, processed foods, cooked carrots, fruit juices... It should also be noted that dairy products have a low glycemic index, but possess powerful insulin-stimulating properties.

Insulin stimulates the secretion of IGF-1 (Insulin-like Growth Factor-1), also known as somatomedin C, which increases the levels of androgens in the blood. Androgens, through a positive feedback mechanism, also stimulate the secretion of IGF-1. Thus, androgens and IGF-1 stimulate the secretion of sebum, which is the origin of acne. In addition to stimulating the secretion of androgens, IGF-1 reduces the quantity of the transcription factor FOXO1 in the cell nucleus, leading to the activation of mTORC1, which is involved in the phenomena of excessive sebum secretion and hyperkeratinisation. mTORC1 is also activated by leucine, an amino acid found in meat and dairy products.

Thus, foods with ahigh glycaemic index, dairy products, as well as meat are risk factors in the development of acne.

A healthy diet will help you limit the development of acne spots by soothing skin inflammation. The following foods should be prioritised to take care of acne-prone skin:

• Foods with a low glycemic index:

  Foods with a high glycemic index stimulate the secretion of insulin, which triggers reactions conducive to the onset of acne. Therefore, replace them with foods with a moderate or low glycemic index, such as whole grains, fruits and vegetables, legumes or even dried vegetables.

• Foods rich in omega-3:

  Foods rich in omega-3 inhibit the secretion of IGF-1, thereby reducing the overproduction of sebum and hyperkeratinisation. Furthermore, they inhibit the synthesis of leukotriene B4 (LTB4), which is a mediator of inflammation. Thus, the consumption of foods rich in omega-3, such as oily fish (salmon, mackerel, etc...), oilseeds (nuts, etc...), linseed and walnut oils, decrease inflammatory and non-inflammatory acne lesions. According to recommendations, the intake of omega-3 should be between 0.8 and 1.1 g/day.

• Foods high in zinc:

  Zinc is a trace element that possesses anti-inflammatory, antibacterial and healing properties that are highly beneficial for acne. Indeed, it inhibits the growth of the bacteria responsible for acne P. acnes and reduces the activity of the sebaceous glands due to its anti-androgenic activity. Therefore, consume foods rich in zinc, such as oysters, eggs, whole grains, legumes and oilseeds.

• Dairy product substitutes:

  Dairy products are rich in leucine and significantly stimulate insulin secretion, promoting the onset of acne. Thus, replace dairy products with substitutes such as plant-based milks (almond milk, oat milk, etc...).

• VARIGOS G. A. & co. A low-glycemic-load diet enhances symptoms in acne vulgaris patients: a randomized controlled trial. The American Journal of Clinical Nutrition (2007).

• PUSHPINDER S. Therapy in Dermatology: A Review. (2014).

• TAN J. & al. Effects of diet on acne and its response to treatment. American Journal of Clinical Dermatology (2021).

• MICALI M. D. & et al. Diet and acne: a review of the evidence from 2009 to 2020. International Journal of Dermatology (2021).