Field Notes

Mono- vs Polyunsaturated Fats in Patients
With Metabolic Syndrome

It's hard to think of the typical muffin, often loaded with saturated fat and a high calorie count, as a healthful food option. But a batch of muffins, made with a special recipe formulated by the USDA, yielded unexpected health benefits during a first-of-its-kind clinical study at the University of Maryland School of Medicine.

The study looked at a way to substitute animal-based saturated fats for plant-based unsaturated fats in muffins made for patients with metabolic syndrome, a group of risk factors that affect about one-third of adults in the United States, increasing their chance of developing cardiovascular disease and type 2 diabetes.

The researchers tested the two varieties of unsaturated fats: monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs). Compared with the MUFA group, patients in the PUFA group lost more weight, had lower blood pressure and triglyceride levels, and increased dilation of blood vessels (a healthful response). Twenty-five percent of PUFA participants converted from metabolic syndrome to metabolically normal vs 10% of MUFA subjects.

"The results surprised us because, based on other studies elsewhere, we hypothesized that MUFA would be superior to PUFA for weight loss and improvement in heart-related parameters," says lead study author Michael Miller, MD, a professor of cardiovascular medicine at the University of Maryland School of Medicine and preventive cardiologist at the University of Maryland Medical Center. "The muffins were from a USDA recipe developed specifically for this study, and both varieties tasted really good."

Miller adds that while more research is needed after this small study with 39 participants, "The bottom line from our research is that PUFA may be the substitute of choice for saturated fat, especially in men and women who are overweight, have hypertension, diabetes, or the metabolic syndrome."

Miller says the response in this study, published in the Journal of Clinical Lipidology, may confirm other research findings about polyunsaturated fats: "Recent data suggest that PUFA (but not MUFA) activates signaling in the brain to reduce appetite, so this may be one reason for the bigger weight drop between the groups."

Study Design
A total of 39 adult men and women with metabolic syndrome completed the study, designed to measure several cardiovascular risk-associated parameters. Each participant's weight was stabilized on an American Heart Association Step 1 diet for one to two months before the six-month period of the study. Participants also were encouraged to exercise by walking at least three days per week for 30 to 45 minutes during the study.

Participants were randomized to either a low-calorie MUFA-enriched or PUFA-enriched diet for six months, aimed at reducing calorie consumption by 300 per day. The relative percentage of carbohydrates, fat, and protein were kept constant, but the saturated fat content was reduced in both groups from 30% to 25% of total fat intake and replaced with either MUFA or PUFA.

Participants consumed three MUFA (high-oleic sunflower oil) or PUFA (safflower oil) enriched muffins daily. The 3.5-oz muffins each contained 275 kcal. All muffins were prepared in the metabolic kitchen of the USDA in Beltsville, Maryland, and kept frozen in a canister until use. Participants met with an RD weekly for the first four months and then biweekly to collect a fresh supply of muffins and reinforce individual dietary and weight loss recommendations.

Miller and his team are considering evaluating other healthful PUFA fats, including plant- and marine-derived omega-3s.

— Source: University of Maryland Medical Center/School of Medicine


Possible Small Increase in Obesity Among US Teens
in Recent Years

Among US children and adolescents aged 2 to 19, the prevalence of obesity in 2011–2014 was 17%, and over approximately the last 25 years, the prevalence has decreased in children aged 2 to 5 years, leveled off in children aged 6 to 11, and increased among adolescents aged 12 to 19, according to a study appearing in JAMA.

Previous analyses of obesity trends among children and adolescents showed an increase between 1988 and 1994 and 1999 and 2000, but no change between 2003 and 2004 and 2011 and 2012, except for a significant decline among children aged 2 to 5. Cynthia L. Ogden, PhD, of the National Center for Health Statistics, Centers for Disease Control and Prevention (CDC) in Hyattsville, Maryland, and colleagues investigated trends in the prevalence of obesity and extreme obesity in children and adolescents aged 2 to 19 with measured weight and height in the 1988–1994 through 2013–2014 National Health and Nutrition Examination Surveys. Obesity was defined as a BMI at or above the sex-specific 95th percentile on the CDC BMI-for-age growth charts; extreme obesity was defined as a BMI at or above 120% of the sex-specific 95th percentile on these charts.

Measurements from 40,780 children and adolescents (average age 11 years; 49% female) between 1988 and 1994 and 2013 and 2014 were analyzed. Among children and adolescents aged 2 to 19, the prevalence of obesity in 2011–2014 was 17%, and extreme obesity was 5.8%. Trends in child and adolescent obesity varied by age. During the approximately 25-year period, the prevalence increased until 2003–2004 but then decreased among children aged 2 to 5 (9.4% in 2013–2014). Among children aged 6 to 11, the prevalence increased until 2007–2008 and then leveled off (17.4% in 2013–2014). Among adolescents aged 12 to 19, obesity prevalence increased between 1988 and 1994 (10.5%) and 2013 and 2014 (20.6%).

Trends in extreme obesity prevalence showed no change between 1988 and 1994 and 2013 and 2014 among children aged 2 to 5, whereas it increased among children aged 6 to 11 (4.3% in 2013–2014) and among adolescents aged 12 to 19 (9.1% in 2013–2014).

No significant changes in either obesity or extreme obesity were seen between 2005 and 2006 and 2013 and 2014, suggesting any recent changes among adolescents were small.

— Source: JAMA: The Journal of the American Medical Association