Sugar series part 2: Why limit added sugar?
Last month I wrote about added sugars, and why it's important to look at them separately from sugars naturally in whole foods. To review: sugars in whole foods like fruits, dairy products, and even some vegetables like carrots and yams are buffered by the extra nutrients and bulk of the rest of the food, so they don't have the same effect as pure, refined sugar. When you refine sugar and eat it on its own, or add a bunch of it to other food, that's when it starts being a health risk. That's true no matter where the sugar originally came from, whether it's sugar cane, an ear of corn, or an apple.
This is borne out by the research, which shows that added sugars are a huge health risk, while foods in their whole state with naturally-occurring sugars are generally pretty good for you. I read the Berkeley Wellness Letter, a nutrition newsletter published by the School of Public Health at UC Berkeley, and they recently published a roundup of the accumulating research that sugar consumption is a major health concern in the United States. In this article, I'm going to talk about some of these studies.
Sugar used to be considered a health risk mainly for diabetes and cavities. This is still true, and in fact a review in Mayo Clinic Proceedings confirmed that added sugar is the "principal driver" of the type 2 diabetes epidemic because it contributes to metabolic problems and insulin resistance (the same review concluded that added fruit consumption is linked to reduced diabetes risk, by the way). But studies are now linking high sugar consumptions to a much wider range of serious health problems, including heart disease, hypertension, strokes, cancer, and even rheumatoid arthritis.
One important recent study analyzed national data on sugar consumption from the past 20 years and linked high sugar consumption rates to cardiovascular disease, such as heart attacks. The people who consumed the most sugar were almost three times as likely as the people who consumed the least sugar to die of cardiovascular disease. Even when they controlled for physical activity, body weight, overall diet quality, and other factors, there was still an increased risk. Other studies found that increased sugar intake is linked to increased risk of stroke and hypertension (high blood pressure) as well. In fact, a review concluded that sugar probably contributes more to hypertension than sodium.
Why would sugar have this effect on heart health? One recent clinical trial provided a clue: even though sugar contains no fat, eating more sugar increases "bad" cholesterol and triglycerides in your bloodstream. Researchers at UC Davis had young adults drink beverages with different levels of sugar for two weeks. At the end, those who drank beverages with no sugar had no difference in their cholesterol and triglycerides. But for the rest, the more sugar in their drinks, the higher levels of these risk factors.
Stated more positively, cutting sugar can quickly make you healthier. This past fall, a rigorous new study made headlines when it showed that cutting the sugar in a group of children's diets improved their health in just ten days. Researchers removed added sugar from the diets of about 50 children who had a high risk of diabetes and related disorders, replacing them with other carbohydrates to keep the total calories the same. After ten days, the children showed dramatic improvements in blood pressure, cholesterol readings and other health markers with little or no change in weight.
Refined sugar is unique in that you really don't need to eat it at all, unlike many other foods considered to be unhealthy such as fat or salt. You could just cut all added sugar out of your diet and be much, much healthier. For some people, that's the best approach. For others (like me), that feels unnecessarily cruel. The good news is that you can eat a little sugar every day and still be pretty healthy. How to keep your sugar consumption under recommended limits will be the subject of the third part of this series.