Sugars and simple carbs in general get a bad rep, and deservedly so. Their negative effects on blood glucose and insulin regulation, weight gain and inflammation is undeniable, yet sweets, treats and desserts are a part of many cultures and traditions (birthday cake anyone?). While the occasional spike in dietary sugars isn’t going to give you diabetes, the bigger problem is what happens when not just sugars, but simple, refined carbohydrates, are consumed regularly, on the daily. The result: in addition to mucking up your glucose/insulin regulation, it can show up all over your face… and your scalp, neck, back and other places. Your skin isn’t just a barrier to protect your inner body tissues. It’s weaved with your immune system and your circulatory system and responds to what’s going on inside of you.
Many of us remember being told as teenagers that eating too much chocolate would give you pimples, but the effects of a high glycemic load diet go so much further than that. Dietary simple sugar consumption can accelerate skin aging, exacerbate autoimmune skin disorders like psoriasis, and yes, it can make acne a lot worse.
For those experiencing these types of skin flare-ups or changes, a high-quality topical or skin regimen alone isn’t going to solve your skin problems since those problems lay much further below the surface.
AGEs and Skin Aging
Glycation occurs when either glucose or fructose molecules bind to proteins, lipids or nucleic acids, at random molecular sites, creating advanced glycation end products (AGEs). In doing so, they effectively inhibit the function of these molecules. The process of glycation is a vicious cycle for molecular damage: AGEs themselves increase the formation of free radicals (like reactive oxygen species) and oxidative stress, but the presence of reactive oxygen species (ROS) themselves can accelerate the process of glycation.
AGEs were first associated with the development of diabetic complications, but are now seen in aged skin as well, since glycation changes the structure, morphology and function of skin tissue.1 Since collagen has a relatively slow turnover rate, it is particular vulnerable to glycation.
AGEs can form adducts or cross-links with collagen proteins, attaching to collagen lysine side-chains. This modifies the collagen surface, changing how collagen interacts with its surrounding cells and proteins, leading to stiffness, inflammation and poor wound healing.2
Glycation can prolong collagen turnover by making it more resistant to degradation by matrix metalloproteinases (MMPs). Meanwhile elastin and fibronectin proteins in skin tissue can also be affected, as well as filaments of keratinocytes. In keratinocytes, increased glycation leads to greater expression of pro-inflammatory cytokines and premature aging.1
AGEs are a product of dietary sugars, but also from specific cooking methods of foods such as grilling, frying, deep-frying and roasting. They are easily absorbed by the gut and enter circulation where they can start binding to molecules forming protein cross-links, inflammation and free radicals.
They are also accumulated with increased UV radiation via oxidative stress. AGEs themselves can easily donate electrons to form free radicals, further inducing oxidative stress, and the look of skin aging.
The safest cooking methods for reducing intake of AGEs are boiling and steaming. Combining this with a low-glycemic diet can reduce the formation of glycated collagen by 25% in just four months.1 Certain herbs and spices can also help inhibit AGE production including: cinnamon, cloves, oregano, ginger, garlic. Meanwhile some preliminary research suggests that antioxidants and nutrients such as alpha lipoic acid, L-carnitine, taurine, bioflavonoids such as EGCG, benfotiamine, Vitamin E, B-Vitamins and zinc may also inhibit AGE formation.1
Sugars and Psoriasis
Apart from AGEs, sugar intake can affect other areas of skin health and inflammation, often from its effect on the gut microbiome.
Psoriasis, being a chronic inflammatory autoimmune skin disorder involves the hyperproliferation and abnormal differentiation of keratinocytes. It’s also associated with obesity, diabetes, cardiovascular diseases and inflammatory bowel disorders.3 Dietary choices can greatly impact disease progression and management, as flare-ups are associated with higher intakes of fried and fatty foods, refined carbohydrates and simple sugars. Animal studies have found that high fructose and glucose intakes increase serum IL-17 levels and promotes Th17 differentiation by up regulating mitochondrial ROS in T cells.3 IL-17 in particular is a main component of skin inflammation.4
It’s well-established that following a standard Western diet, characterized by high intakes of refined sugars and animal-based saturated fats, influences the gut microbiome and causes dysbiosis. Species like E. coli can more easily proliferate while protective bacteria such as Firmicutes bacteria are reduced. The change in this balance can easily increase inflammation both in the gut and throughout the body.
In animal studies following a Western diet, even short-term, has been shown to increase epidermal thickness skin inflammation and Munro’s microabscesses (epidermal neutrophil infiltration associated with psoriasis).3,4
Acne and Diet
Acne is an incredibly common skin condition which presents as excess sebum production, follicular hyperkeratinization, and/or from the colonization and proliferation of specific bacteria and/or yeast within follicles.5 Yet, historically, certain populations such as the Canadian Inuit, South African Zulus, Japanese Okinawans and Kitavan islanders of Papua New Guinea did not experience acne until adopting a Western diet high in processed foods and refined sugars.6
Acne can occur due to hormonal factors and infections, but as we know, it’s heavily influenced by dietary choices and internal inflammation.
In one study of Thai adolescents and adults, the severity of acne increased with higher intakes of chocolate (greater than 100g per week), oily and fried foods (more than three times per week), and white rice.7 Meanwhile vegetable consumption was associated with lower acne severity.
In another study of 43 male patients in Australia, switching to a low-glycemic load diet, consisting of 45% low-GI carbohydrates, 25% protein and 30% fats for 12 weeks led to significantly less acne lesions compared to the group who remained on a high glycemic load diet.5
Health that starts on the inside (and what you put into your body) will show on the outside. Skin aging can be accelerated with the intake of sugars and other sources of AGEs, while autoimmune conditions that brew internal inflammation can present as skin inflammation and flare-ups.
Plant-based diets with a low-glycemic load are consistently associated with a lower prevalence of acne5,7,8, but this can also translate to other inflammatory skin conditions and skin health in general.
1. Nguyen HP, Katta R. (2015). Sugar Sag: Glycation and the Role of Diet in Aging Skin. Skin Therapy Lett. 20(6):1-5
2. Snedeker JG, Gautieri A. (2014). The role of collagen crosslinks in ageing and diabetes – the good, the bad, and the ugly. Muscles Ligaments Tendons J. 4(3):303-8
3. Kanda N, Hoashi T, Saeki H. (2020). Nutrition and Psoriasis. Int J Mol Sci. 21(15):5405
4. Shi Z, Wu X, Santos Rocha C, et al. (2021). Short-Term Western Diet Intake Promotes IL-23‒Mediated Skin and Joint Inflammation Accompanied by Changes to the Gut Microbiota in Mice. J Invest Dermatol. 141(7):1780-1791
5. Smith RN, Mann NJ, Braue A, et al. (2007). The effect of a high-protein, low glycemic-load diet versus a conventional, high glycemic-load diet on biochemical parameters associated with acne vulgaris: a randomized, investigator-masked, controlled trial. J Am Acad Dermatol. 57(2):247-56
6. Baldwin H, Tan J. (2021). Effects of Diet on Acne and Its Response to Treatment. Am J Clin Dermatol. 22(1):55-65
7. Roengritthidet K, Kamanamool N, Udompataikul M, et al. (2021). Association Between Diet and Acne Severity: A Cross-sectional Study in Thai Adolescents and Adults. Acta Derm Venereol. 101(12):adv00611
8. Dall’Oglio F, Nasca MR, Fiorentini F, Micali G. (2021). Diet and acne: review of the evidence from 2009 to 2020. Int J Dermatol. 60(6):672-685.