Variations In Fat Intake Research Articles

Dietary fat and obesity: an epidemiologic perspective

The observation that dietary fat has an effect on weight gain and the development of obesity that is larger than would be expected on the basis of fat's energy value is mainly experimental. Several methodologic problems limit the interpretation of epidemiologic studies of the association between dietary fat intake and obesity. Among the issues relevant in this context are underreporting of energy and fat intakes, dieting behavior, inadequate control for variables such as energy expenditure, and limited between-subject variation in fat intake in developed countries. Different types of epidemiologic studies suffer from different types and magnitudes of bias and many conflicting results can be obtained. Ecologic and cross-sectional studies especially suffer from these biases. The more appropriate type of study (ie, prospective studies of fat intake and subsequent weight gain) was carried out in several countries but conflicting results were obtained. Overall, the observed associations seem to depend on the stage of cultural transition of the population studied (eg, modernization compared with postmodernization). Current epidemiologic methods are inadequate for performing valid studies of the relation between percentage of energy from dietary fat and obesity. Specifically designed prospective studies of unbiased estimates of energy balance are necessary. Appropriate control for confounders and emphasis on the possibility that genetic predisposition plays a role will also be necessary. At this stage there is no conclusive evidence from epidemiologic studies that under isoenergetic conditions dietary fat intake promotes the development of obesity more so than other macronutrients.

Food patterns associated with intakes of fat, carbohydrate and dietary fibre in a cohort of Danish adults followed for six years.

To examine associations between food consumption patterns, measured by a short food frequency questionnaire (FFQ), and the intakes of fat, carbohydrates and fibre over time, and in relation to recommended guidelines. The same 329 individuals had their diet intake measured by a short FFQ and a thorough diet history interview, first in 1987/88, and again six years later in 1993/94. The County of Copenhagen, Denmark. Three hundred and twenty-nine men and women, aged 35-65 y selected randomly from a large population sample. At both examinations fat energy displayed the strongest positive associations with the intake of animal fats and negative correlations with the vegetables. These food items explained most of the total explained variation in fat intake. In general the associations between food items and intakes of carbohydrates and fibre were similar but inverse, to those found for fat. During the study period median fat energy decreased from 41-38%. A less frequent intake of animal fats over time predicted an increase in fat energy both among men and women, while a more frequent intake of fruit and pasta, and a less frequent intake of cakes was associated with an increase in dietary fibre. Food items like animal fats, vegetables and certain high starch foods can predict compliance to dietary guidelines for fat and carbohydrates. The study also shows that the food pattern of this Danish cohort has changed in the direction of a more healthy diet during the six years of follow-up. This study was granted by the Danish Agricultural and Veterinary and Danish Medical Councils and the Danish Health Insurance foundation.

Mineral utilization of vegetarians: impact of variation in fat intake

One of the benefits associated with consumption of vegetarian diets is that these diets usually have lower contents of total fat and cholesterol and have more favorable polyunsaturated-to-saturated fatty acid ratios. Thus, use of vegetarian diets tends to fit recommendations relative to decreasing risk of cardiovascular disease. However, changes in level and kind of dietary fat may result in alterations in utilization of essential minerals. In studies carried out at the University of Nebraska using healthy human subjects, low-fat diets were found to inhibit the absorption of iron, zinc, manganese, and calcium. Further research indicated that both increase in fatty acid chain length and increase in saturation of fatty acids resulted in a decrease in Ca bioavailability. However, increased dietary cholesterol levels tended to increase Ca bioavailability.

Caffeine ingestion and breast cancer. A negative correlation.

The potential association of breast cancer and caffeine intake was examined using international aggregate data. Death rates from breast cancer were correlated with caffeine ingestion from tea and coffee sources in 44 countries. By using multiple regression analysis, the authors demonstrated that 85% of the international variation in breast cancer rates is associated with variations in fat intake. When this is accounted for, the partial correlation of breast cancer rates with caffeine intake is negative (and significant at P less than 0.05). When the data are weighted by populations in each country, the negative partial correlation of caffeine with breast cancer disappears, but the strong positive association with fat intake remains unchanged. Although there have been suggestions that caffeine exacerbates fibrocystic disease of the breast and may be a causal factor in breast cancer, data from this study do not support a positive association between caffeine intake and subsequent development of breast cancer.

Food intake in diabetic rats: isolation of primary metabolic effects of fat feeding.

The effects of varying dietary fat content on food intake and metabolism in streptozotocin-diabetic rats were examined. The metabolic consequences of fat feeding were separated from the marked adjustments in voluntary food consumption that occur when diabetic rats are fed diets containing different amounts of fat by feeding rats a fixed ration of food in which either fats or carbohydrates were reduced by equicaloric amounts, or in which only the concentration of fat, but not other dietary nutrients, was varied systematically. Resulting changes in metabolism and subsequent ad libitum food intake on refeeding were then measured. Rats did not increase their food intake after a prior reduction in carbohydrate consumption but did so after an equicaloric reduction in fat consumption. Urinary glucose excretion during rationing was a function of carbohydrate consumption and was not predictive of changes in food intake during refeeding. The more fat that rats consumed during rationing, the higher their levels of plasma triglycerides and ketone bodies were at the time of refeeding and the less they ate when allowed to eat ad libitum. The orderly changes in food consumption and in plasma triglycerides and ketones observed with variations in fat intake suggest that the effects of fat feeding on food intake in diabetic rats are mediated through the oxidation of ingested fat.