Abdominal subcutaneous adipose tissue: a protective fat depot?

OBJECTIVE: Obesity is associated with increased metabolic and cardiovascular risk. The ectopic fat hypothesis suggests that subcutaneous fat may be protective, but this theory has yet to be fully explored. RESEARCH DESIGN AND METHODS: Participants from the Framingham Heart Study (n = 3,001, 48.5% women) were stratified by visceral adipose tissue (VAT) into sex-specific tertiles. Within these tertiles, age-adjusted abdominal subcutaneous adipose tissue (SAT) tertiles were examined in relation to cardiometabolic risk factors. RESULTS: In the lowest VAT tertile, risk factor prevalence was low, although systolic blood pressure in women and rates of high triglycerides, impaired fasting glucose, hypertension, and the metabolic syndrome in men increased with increasing SAT tertile (all P < 0.04). In contrast, in the top VAT tertile, lower triglycerides were observed in men with increasing SAT (64.4% high triglycerides in SAT tertile 1 vs. 52.7% in SAT tertile 3, P = 0.03). Similar observations were made for women, although results were not statistically significant (50.6% high triglycerides in SAT tertile 1 vs. 41.0% in tertile 3, P = 0.10). Results in the highest VAT tertile were notable for a lack of increase in the prevalence of low HDL in men and women and in rates of impaired fasting glucose in men with increasing subcutaneous fat, despite sizable differences in BMI across SAT tertiles (27.1 to 36.3 kg/m(2)[women]; 28.1 to 35.7 kg/m(2)[men]). CONCLUSIONS: Although adiposity increases the absolute risk of metabolic and cardiovascular disease, abdominal subcutaneous fat is not associated with a linear increase in the prevalence of all risk factors among the obese, most notably, high triglycerides.

Factores de riesgo cardiovascular. Perspectivas derivadas del Framingham Heart Study / Cardiovascular risk factors. Insights from Framingham Heart Study

La epidemiología se dedica al estudio de la distribución y la frecuencia de la enfermedad y sus determinantes en la población. La epidemiología cardiovascular se inició en los años treinta como consecuencia de los cambios observados en las causas de mortalidad. En los años cincuenta se pusieron en marcha varios estudios epidemiológicos para aclarar las causas de la enfermedad cardiovascular. Cuatro años después del inicio del Framingham Heart Study, los investigadores identificaron que el colesterol elevado y la presión arterial alta eran factores importantes en cuanto a la aparición de la enfermedad cardiovascular. En los años siguientes, el estudio de Framingham y otros estudios epidemiológicos contribuyeron a identificar otros factores de riesgo, que ahora se consideran ya clásicos. Al acuñar la expresión «factor de riesgo», el Framingham Heart Study facilitó un cambio en el ejercicio de la medicina. En la actualidad, definimos un factor de riesgo como un elemento o una característica mensurable que tiene una relación causal con un aumento de frecuencia de una enfermedad y constituye factor predictivo independiente y significativo del riesgo de contraer una enfermedad. En esta revisión de carácter narrativo, presentaremos algunos de los resultados más relevantes respecto a las causas de la enfermedad cardiovascular derivados del Framingham Heart Study, centrándonos en la identificación de los factores de riesgo, el análisis de su capacidad predictiva y las consecuencias que estas observaciones tienen en lo relativo a la prevención

Epidemiology involves the study of disease frequency and its determinants within the population. Cardiovascular epidemiology began in the 1930s as a result of changes observed in the causes of death. In the 1950s, several epidemiological studies were set in motion with the aim of clarifying the cause of cardiovascular disease. Four years after the Framingham Heart Study started, researchers had identified high cholesterol and high blood pressure levels as important factors in the development of cardiovascular disease. In subsequent years, the Framingham study and other epidemiological studies have helped to identify other risk factors, which are now considered classical risk factors. By coining the expression «risk factor», the Framingham Heart Study helped to bring about a change in the way medicine is practiced. Today, a risk factor is defined as a measurable characteristic that is causally associated with increased disease frequency and that is a significant independent predictor of an increased risk of presenting with the disease. This wide-ranging overview describes some of the most important insights into the causes of cardiovascular disease to have come from the Framingham Heart Study. The emphasis is on the identification of risk factors, and the assessment of their predictive ability and their implications for disease prevention