When it comes to managing or preventing disease, carbohydrates play a major role. But, forget the bad news you've heard about carbohydrates in the past: science paints a different picture than the one often portrayed in the media (carbs after 4:17pm are bad, NEVER eat grains, ONLY eat fruit, thinking about carbs makes you fat, bla bla bla).
Inflammation is now recognized as an important component - and sometimes even a central mechanism - in many chronic diseases, including asthma, celiac disease, IBD, Crohn's, arthritis, atherosclerosis, diabetes, obesity, Alzheimer's, and cancer. Believe it or not, your DIET can affect inflammatory responses in the body, leading researchers and scientists to believe that modification of these inflammatory responses through food can, in fact, help manage or reduce your risk for disease.
Today, we discuss how these inflammatory responses change in response to carbohydrates with varying glycemic index and load.
.....wait, carbs with varying what?
Simply put, the glycemic index (GI) is the potential of the carbohydrate in a food to raise blood glucose. By definition, high-glycemic foods result in higher and more rapid increases in blood glucose compared to low-glycemic foods.
However, because the AMOUNT of carbohydrate consumed also affects blood glucose levels, a more accurate indicator of the relative glycemic response is the glycemic load (GL), since the glycemic load takes into account the grams of carbohydrates consumed.
For example, brown rice has a lower glycemic index than a potato, but if you eat 1 cup of brown rice and only a sliver of potato, the blood glucose response to the brown rice will still be greater because of the difference in quantity - there are way more grams of carbohydrates in 1 cup of brown rice than in a tiny sliver of a potato.
Plenty of observational studies show a correlation between high blood glucose concentrations and increased risk for chronic disease, especially heart disease. In fact, studies done on both glycemic index and load further support the theory that post-prandial (after you eat) glycemic response plays a role in the risk, development, and progression of these diseases.
Take, for example, a study done by Liu et al, using data from 75,000 women (that's a lot) in the Nurses' Health Study. After the 10-year follow-up, diets with a high GL doubled the risk of heart disease - even after adjusting for known risk factors! At the 20-year follow-up, GL was the strongest independent predictor of heart disease risk.
So what's the link behind blood glucose and these diseases?
Many scientists believe it's our old frenemy, inflammation. Hyperglycemia can cause inflammation through the production of free radicals and pro-inflammatory proteins, called cytokines. Thus, high-GI and -GL diets likely stimulate inflammation.
Researchers have taken this information and gone one step further, looking at the effects of high- and low-GI/GL diets on biomarkers of inflammation. One study found that adherence to a low-glycemic index and energy-restricted diet lowered levels of C-reactive protein, or CRP, (a commonly used marker of inflammation) by 48% in overweight or obese adults! The cool part is that individuals in the study who followed a low-fat, energy-restricted diet only reduced CRP by 5%, even though BOTH groups experienced comparable weight loss and body composition changes.
Another study, involving 80 healthy men and women, showed that when compared to the high-glycemic load group, adherence to a low-glycemic load diet reduced CRP by about 22% in overweight and obese subjects, as well as increased levels of a hormone called adiponectin that plays a key role in protecting against several cancers and metabolic disorders. The diets were identical in carbohydrate content, calories, and macronutrients.
Ok, ok, so glycemic index and load likely matter when it comes to health and reducing inflammation. So what's the takeaway?
QUALITY OF CARBS MATTERS.
Against what most diet gurus and self-proclaimed experts declare, it's not about LOW carb; it's about SLOW carb.
If you want to help manage or reduce your risk of chronic disease, consume carbohydrates that are less likely to cause rapid spikes in blood glucose, such as intact and whole grains, milk, fruit, nuts and legumes (beans and lentils). Decrease consumption of low-glycemic foods, like those containing a lot of white sugar and white flour (cakes, crackers, cookies, candy), and sugar-sweetened cereals and beverages. While those foods can be enjoyed occasionally, they should never make up the majority of your diet.
Sugar-sweetened cereal + milk >>>> Oatmeal + milk
Soda >>>> Sparkling water with a splash of real fruit juice
Got questions? Want more help managing or reducing your risk of chronic disease? Comment below or get in touch at firstname.lastname@example.org.
I used my brain to write this, but also these other things:
Dickinson S, et al. High–glycemic index carbohydrate increases nuclear factor-κB activation in mononuclear cells of young, lean healthy subjects. Am J Clin Nutr 2008;87(5):1188–1193.
Micronutrient Information Center. Glycemic Index and Glycemic Load. Available at: http://lpi.oregonstate.edu/mic/food-beverages/glycemic-index-glycemic-load. Accessed February 17, 2016.
Micronutrient Information Center. Inflammation. Available at: http://lpi.oregonstate.edu/mic/micronutrients-health/inflammation. Accessed February 17, 2016.
Neuhouser ML, Schwarz Y, Wang C, et al. A Low-Glycemic Load Diet Reduces Serum C-Reactive Protein and Modestly Increases Adiponectin in Overweight and Obese Adults. Journal of Nutrition 2011;142(2):369–374.
Pereira MA, Swain J, Goldfine AB, Rifai N, Ludwig DS. Effects of a low-glycemic load diet on resting energy expenditure and heart disease risk factors during weight loss. JAMA 2004; 292(20): 2482-90.