Ask Tufts Experts

Does regular exercising enlarge one’s lipid particles (HDL, LDL and VLDL), which is supposed to be beneficial to one’s health?

“The major determinant of VLDL, LDL and HDL particle size is the level of triglyceride in the blood,” replies Ernst J. Schaefer, MD, chief of the Lipid Metabolism Laboratory at Tufts’ Jean Mayer USDA Human Nutrition Research Center on Aging. “Regular exercise and weight loss if indicated can help lower triglyceride to less than 150 mg/dl. Below this level, most of LDL particles are type or large particles.”

I have seen many emails and Web postings about people getting sick from the artificial sweetener aspartame. I am a diet cola consumer, so I wonder: Is aspartame dangerous?

The Internet is full of misinformation about aspartame, according to David Hattan, PhD, of the Food and Drug Administration’s (FDA) division of health effects evaluation. Hattan says there is no “credible evidence,” to support, for example, rumored links between aspartame and systemic lupus or multiple sclerosis. True, ingesting aspartame results in the production of substances that could be toxic at high doses: methanol, formaldehyde and formate. But the amounts are small—less methanol, for instance, than found in tomatoes or citrus juices.

The FDA does require products containing aspartame to be labeled for phenylalanine, an amino acid that can cause problems for people with a rare hereditary condition. Another amino acid in aspartame that’s the subject of Internet rumors, aspartic acid, could cause brain damage at extremely high doses. But the FDA calculates that most aspartame users consume only 4 to 7 percent of the safe maximum daily intake. Other claims against aspartame, such as supposed links to seizures and birth defects, have failed to be supported by testing, even when lab animals ingested aspartame at doses far higher than humans would ever consume. The FDA says aspartame, sold under trade names such as NutraSweet and Equal, is one of the most thoroughly tested and studied food additives the agency has ever approved. More than 100 toxicological and clinical studies confirm that aspartame is safe for the general population.