Diet soda and the metabolic syndrome

Some foods seem like a lesser evil initially, only to reemerge as even worse than the food they replaced.

The big shock was when we found out that replacing butter (high in saturated fat) with margarine (polyunsaturated fat), was discovered many years later to not only decrease our joy in eating (in my opinion reason enough to reject margarine) , but introduced trans-fats to our body, which are apparently worse than saturated fat.

Are we now going to discover that diet soda is as damaging as regular soda?

Several reports have demonstrated that increased consumption of soft drinks is linked to the growing epidemic of obesity and type 2 diabetes in childhood and adolescence.

But a new study published this week in Circulation observes that “Western Diet” and diet soda specifically, promote the incidence of the Metabolic Syndrome.

The metabolic syndrome is a group of risk factors including abdominal obesity, high blood pressure, elevated triglycerides, low levels of high-density lipoprotein (HDL or “good”) cholesterol and high fasting glucose levels. The presence of three or more of the factors increases a person’s risk of developing diabetes and cardiovascular disease.
The metabolic syndrome has become increasingly common in the United States. It is estimated that over 50 million Americans have it. It seems like wherever the Western dietary patterns of eating spread, obesity and the metabolic syndrome follow, with increased incidence of diabetes and heart disease not far behind.

The findings of this study, led by Lyn M Steffen, emerged from an analysis of dietary intake of 9,514 participants aged 45 to 64 years old followed for 9 years.

Researchers assessed food intake using a 66-item food frequency questionnaire. From those responses, they categorized people by their dietary preferences into a “Western-pattern” diet or a “prudent-pattern” diet.

In general, the “Western-pattern” diet was heavy on refined grains, processed meat, fried foods, red meat, eggs and soda, and light on fish, fruit, vegetables and whole grain products.

“Prudent” diet eating patterns, by contrast, favored cruciferous vegetables (e.g., cabbage, radish and broccoli), carotenoid vegetables (e.g., carrots, pumpkins, red pepper, cabbage, broccoli and spinach), fruit, fish and seafood, poultry and whole grains, along with low-fat dairy.

Researchers also assessed associations with individual food items: fried foods, sweetened beverages (regular soda and fruit drinks), diet soda, nuts and coffee.

After these nine years of follow-up, 3,782 (nearly 40 percent) of the participants developed the metabolic syndrome.
After adjusting for demographic factors, smoking, physical activity and energy intake, consumption of a “Western” dietary pattern was adversely associated with metabolic syndrome.

When Steffen and colleagues analyzed the results by specific foods, they found that meat, fried foods and diet soda were all significantly associated with increased risk of metabolic syndrome, but consumption of dairy products was beneficial.

The strong association between diet soda consumption and the metabolic syndrome was surprising to the authors. Diet soda has no sugar and no calories, so one would assume it does not contribute to poor glucose control or obesity. However, this is not the first time diet soda is implicated in the metabolic syndrome. Recent data from the Framingham Heart Study found a 56% increased risk for the Metabolic syndrome among those consuming 1 or more servings of diet soda per day.

The authors discuss this finding, and cite a study in rats, that suggests that artificial sweetener consumption impairs the body’s ability to predict the caloric content of food, and may lead to increased intake and weight gain.

Further studies will hopefully help elucidate why diet sodas don’t seem to be the answer to the growing waist line.
Dr. Ayala