Diet and Acne - the glycemic index

Any discussion about acne always involves a discussion about diet. There's a lot of information that's thrown around about the connection between food and acne. Some true. Some false. When we talk about acne and diet, we like to look at the science.

For now I'll park the (sometimes controversial) discussion about the role dairy, gluten and sugar play in acne; and instead discuss the glycemic index.

There is absolutely emerging evidence that foods with a high glycemic index (GI) may be one of the (multiple) factors that trigger or worsen acne. 

What is the Glycemic Index?

The glycemic index (GI) is a value used to measure how much specific foods increase blood sugar levels.  Foods are classified as low, medium, or high glycemic foods and ranked on a scale of 0–100.

The lower the GI of a specific food, the less it may affect your blood sugar levels.

Here are the three GI ratings:

  • Low: 55 or less
  • Medium: 56–69
  • High: 70 or above

Foods high in refined carbs and sugar are digested more quickly and often have a high GI, while foods high in protein, fat, or fibre typically have a low GI. Foods that contain no carbs are not assigned a GI and include meat, fish, poultry, nuts, seeds, herbs, spices, and oils.

Other factors that affect the GI of a food include the ripeness, cooking method, type of sugar it contains, and amount of processing it has undergone.

Foods with a high GI include:

    • Bread: white bread, bagels, naan, pita bread
    • Rice: white rice, jasmine rice, arborio rice
    • Cereals: instant oats, breakfast cereals
    • Pasta and noodles: lasagna, spaghetti, ravioli, macaroni, fettuccine
    • Starchy vegetables: mashed potatoes, potatoes, french fries
    • Baked goods: cake, doughnuts, cookies, croissants, muffins
    • Snacks: chocolate, crackers, microwave popcorn, chips, pretzels
    • Sugar-sweetened beverages: soda, fruit juice, sports drinks

Foods with a low GI include:

    • Fruits: apples, berries, oranges, lemons, limes, grapefruit
    • Non-starchy vegetables: broccoli, cauliflower, carrots, spinach, tomatoes
    • Whole grains: quinoa, couscous, barley, buckwheat, farro, oats
    • Legumes: lentils, black beans, chickpeas, kidney beans
Foods without a GI value include:
    • Poultry: chicken, turkey, duck, goose
    • Meat: beef, bison, lamb, pork
    • Seafood: tuna, salmon, shrimp, mackerel, anchovies, sardines
    • Oils: olive oil, coconut oil, avocado oil, vegetable oil
    • Nuts: almonds, macadamia nuts, walnuts, pistachios
    • Seeds: chia seeds, sesame seeds, hemp seeds, flax seeds
    • Herbs and spices: turmeric, black pepper, cumin, dill, basil, rosemary, cinnamon

So whats the problem with high glycemic index?

Foods with a high GI cause a spike in blood sugar levels which lead to a spike in insulin and insulin-like growth factor-1 (IGF-1). IGF-1 is thought to effect androgen hormones which drive acne.   High levels of IGF-1 lead to insulin resistance and the following:

–  Keratinocyte proliferation which leads to skin inflammation > acne

–  Sebocyte proliferation which leads to comedome (congested pimples) formation

- Increased androgens, decreased Sex Hormone Binding Globulin (SHBG) > acne

And before we start labelling foods 'good' and 'bad'; remember acne is multi-factorial and not caused by one thing along.

Every case of acne is different, but the science is strong with this link between high GI foods and acne, so it might be worthwhile chatting to your health care practitioner. Also keep in mind there's no quick fix;  it may take 8-12 weeks to see improvement.

Have any comments or questions; please let me know below. 

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