Carbohydrates have an image problem. They have been accused of everything from causing diabetes to obesity to heart disease. And while they can contribute to these conditions, weight-loss programs that focus only on “low-carb” are missing the point.

There are good carbs and bad carbs. It's only poor quality, processed carbohydrates that raise the risk of these diseases and obesity. Good carbs are, well, good for you. You should eat plenty of them. The problem is too many of us are eating too many processed carbohydrates, and a new, global study affirms that.

Eating too many processed, or refined, carbohydrates creates a high glycemic diet that causes a sharp rise in blood sugar.

Carbohydrates are one of the six essential nutrients that all humans need. Naturally occurring and high-quality carbohydrates are found in fruits, vegetables, beans and whole grains. Carbohydrates are broken down to glucose in the body, the sugar that is the body’s main source of fuel or energy.

Today, however, food manufacturing processes often strip out the beneficial components of naturally occurring carbohydrates — like fiber, and turn them into poor-quality carbohydrates in the form of white flour, white sugar, white rice, white pasta and instant mashed potatoes, all in an effort to make them easier to eat, easier to cook. Think about the all the snack foods — from packs of cupcakes to bags of chips — lining the aisles of your local convenience store.

Eating too many processed, or refined, carbohydrates creates a high glycemic diet that causes a sharp rise in blood sugar. The glycemic index is a tool used to rank foods according to how they affect blood sugar levels. Foods that are high on the glycemic index and bring on this spike in blood sugar include white bread, white rice, pasta and potatoes. Fruits, vegetables, beans and whole grains are low on the glycemic index and produce a milder increase in blood sugar when eaten.

Modern food manufacturing processes remove the beneficial components of carbohydrates — like fiber — and turn them into poor-quality carbohydrates — like white flour, white sugar, white rice, white pasta and instant mashed potatoes.

Nearly 138,000 people from five continents between the ages of 35 and 70 years old were followed for an average of about nine years as part of the Population Urban and Rural Epidemiology (PURE) study, which looked at the relationship between diets high in poor-quality carbohydrates and the risk of heart attack, stroke and death.

Participants periodically completed food questionnaires that helped researchers measure their long-term food intake and estimate the glycemic index of the participants’ diets. McMaster University and Hamilton Health Sciences researchers categorized participants' carbohydrate intake according to how specific foods increased blood sugar numbers, and then compared carbohydrate intake to the number of people diagnosed with cardiovascular disease or deaths.

Poor Quality Carbs, Poor Health Results
People who ate a diet consisting of foods in the highest 20 percent of the glycemic index had a 50 percent greater risk of having a heart attack, stroke or dying if they already had a heart condition. Without a pre-existing condition, they were 20 percent more likely to experience one of the conditions or die. The risk was even higher among individuals who were obese.

“The present data, along with prior publications from the PURE and several other studies, emphasize that consumption of poor quality carbohydrates is likely to be more adverse than the consumption of most fats in the diet,” researcher, Salim Yusuf, of McMaster University said in a statement. “This calls for a fundamental shift in our thinking of what types of diet are likely to be harmful and what types are neutral or beneficial.”

Bottom line: Carbohydrates are not all the same. When they are the main type of carbohydrates a person eats, low quality carbohydrates like foods made with white flour and refined sugar contribute to prediabetes and metabolic syndrome and can reduce a person’s lifespan. Foods providing high quality carbohydrates like whole grains, beans and peas, fruits and vegetables can reduce the risk of heart attack and stroke and increase longevity.

The study is published in the New England Journal of Medicine.