New: A treatment designed for rosacea-prone skin

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Une alimentation trop grasse ou trop sucrée provoque l'acné : vrai ou faux ?

Does a diet that is too fatty or too sugary cause acne: true or false?

The causes of acne are multifactorial. However, diet plays a significant role in this skin disease. It is often heard that foods high in fat and sugar cause acne. But what is the reality? This article provides some answers.

A Reminder about Acne.

Acne is achronic inflammatory diseasethat presents itself through the emergence of pimples on the face and/or body. The causes of acne aremultifactorial: genetic, hormonal, stress, the use of certain medications...

In the case of acne, we observe ahypersecretion of sebum(also known as hyperseborrhea) at the level of the hair follicles and sebaceous glands, as well as ahyperkeratinization. The sebum clogs the pores, which are the openings of the sebaceous glands on the skin's surface. This fat-rich environment is conducive to the proliferation of the bacteria responsible for acne,Cutibacterium acnes(formerly known as Propionibacterium acnes), which primarily feeds on sebum. This bacteria secretes pro-inflammatory substances that cause inflammation and the formation of pimples.

Connection between acne and excessive sugar consumption.

Many studies have focused on the link between acne and the glycemic index of the diet. The glycemic index of a food indicates its ability to raise blood sugar levels, that is, the concentration of glucose in the blood.

When a food has a high glycemic index, the level of glucose will rapidly increase in the blood. In response, the pancreas will stimulate the secretion of insulin, which is a hypoglycemic hormone.

Note : A hormone is referred to as hypoglycemic when it reduces the level of sugar in the blood. Conversely, a hyperglycemic 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 (pastries, baked goods, confectionery...), cooked carrots, fruit juices...

Insulinstimulates 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, the androgens and IGF-1 stimulate the secretion of sebum which is the cause of acne. In addition to stimulating the secretion of androgens, IGF-1 reduces the amount of the transcription factor FOXO1 in the cell nucleus, leading to theactivation of mTORC1 which is involved in phenomena of hypersecretion of sebum as well as hyperkeratinization.

Note : mTORC1 is also activated by the leucine, an amino acid that makes up the meat and dairy products.

Note : the dairy products have a low glycemic index but powerful insulin-stimulating properties.

Thus, foods with a high glycemic index, dairy products, as well as meat, are risk factors in the development of acne.

Connection between acne and a diet high in fat.

Although scientific studies have proven that high glycemic index foods, dairy products, and meat are risk factors in the development of acne, no study has established a link between fats (lipids) and acne.

Contrarily, studies have proven that lipids rich in omega-3 reduce the secretion of IGF-1 which is responsible for the overproduction of sebum and the phenomenon of hyperkeratinization. Furthermore, they inhibit the synthesis of leukotriene B4 which is the root cause of inflammation.

However, it is advised against consuming the so-called "trans" saturated fatty acids that are primarily found in processed foods (fast food, sweets, fried foods, deli meats, pastries...). It is better to consume unsaturated fatty acids, such as omega 3 and omega 6, which are essential for the proper functioning of the body. You can find these in nuts, avocados, fatty fish (salmon, sardines..) or even in walnut oil.

Sources:

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

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

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

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