Diets high in carbohydrates boost the concentration of blood glucose and triglycerides which can become problematic at high concentrations when they circulate in the blood. High levels of carbohydrates can also decrease the levels of HDL which escalate the risk of heart disease. It should be noted that not all carbohydrates have this same outcome on blood glucose levels.
The extent of how much a carbohydrate will induce these negative outcomes is directly related to the glycemic index. The authors describe the glycemic index as the measure of how much a food raises blood glucose levels compared with the same amount of glucose or white bread. Another measurement to take into consideration when ingesting a high carbohydrate diets is the glycemic load. The glycemic load is calculated based on the glycemic index of a given food and also on the total amount of carbohydrates it contains.
The study tries to measure the effects of high glycemic index diets and its association with heart disease. The study population included 47,749 adults — 15,171 men and 32,578 women — who completed dietary questionnaires. Questionnaire responses from the study participants allowed researchers to calculate the total carbohydrate intake, the mean glycemic index of the foods consumed and the glycemic loads of the participants’ diets. During a median (midpoint) of 7.9 years of follow-up, 463 participants (158 women and 305 men) developed coronary heart disease.
The top one-fourth of women who consumed the highest percentage of carbohydrates out of the study population overall had roughly double the risk of heart disease as the bottom one-fourth who consumed the least. The researches found that the one-fourth of women who consumed the highest glycemic load had 2.24 times the risk of heart disease compared with the one-fourth of women who consumed the lowest glycemic load. When carbohydrate content was separated based on high and low glycemic index measurements, a higher intake of high-glycemic index foods was significantly associated with a higher likelihood of coronary heart disease. Inversely, low-glycemic index carbohydrates were not associated with this same risk. Based on these results the authors concluded that "a high consumption of carbohydrates from high-glycemic index foods, rather than the overall quantity of carbohydrates consumed, appears to influence the risk of developing coronary heart disease."
The study, however, demonstrated that carbohydrate intake, glycemic index and glycemic load were not significantly associated with heart disease in men. The author noted that adverse changes associated with carbohydrate intake, including triglyceride levels, are stronger risk factors for heart disease in women than in men and this supports the findings of this study.
The researchers concluded, "We tentatively suggest that the adverse effects of a high glycemic diet in women are mediated by sex-related differences in lipoprotein and glucose metabolism, but further prospective studies are required to verify a lack of association of a high dietary glycemic load with cardiovascular disease in men."
Dietary Glycemic Load and Index and Risk of Coronary Heart Disease in a Large Italian Cohort: The EPICOR Study. Arch Intern Med, 2010; 170 (7): 640-647. http://archinte.jamanetwork.com/article.aspx?articleid=225342