Dietary fats intervention studies

Even though milk fat contains some fatty acids that may elevate plasma total and LDL-cholesterol levels, which are risk factors for CHD, this effect is balanced by concurrent increases in levels of anti-atherogenic HDL-choles-terol. In addition, saturated fatty acids reduce plasma levels of atherogenic Lp[a] and produce a less atherogenic LDL particle size. Dietary intervention studies, where there was a substantial reduction in saturated fat intake and plasma cholesterol levels, did not produce an improvement in CHD or total mortality. Prospective epidemiological studies provide no evidence that saturated fatty acids are a risk factor for CHD. Indeed, in two large studies, saturated fatty acids were inversely associated with risk. 

Basic treatment for cancer includes chemotherapy, radiations, and surgery. Strategies for prevention include modification of lifestyle factors and dietary interventions. The role of dietary fat in cancer is controversial. Many prospective studies found an increase in cancer risk (82-84), whereas others reported no association between fat intake and cancer (85-87). 

The compositional characteristics of almond oil show that it is rich in several health-promoting nutrients, many of which may be responsible for the observed benehcial effects of dietary almond consumption in cardiovascular diseases (11) and in weight management (12), however, few investigations have explored this topic. Hyson et al. (13) conducted a dietary intervention study to determine whether the consumption of whole almonds or almond oil for 6 weeks would result in similar or different effects on plasma lipids and ex vivo LDL oxidation. Both groups consumed diets with identical almond oil and total fat levels. This study showed that both whole almond and almond oil consumption caused similar reductions in plasma cholesterol and LDL (4% and 6%, respectively) as well as a 14%... 

Both the total fat intake and the ratios between FAs of different classes influence the activity of immune cells. Such information was initially obtained through epidemiological human studies, and studies conducted with cultured cells and animal models. These studies showed that EFAs are required for the growth and maintenance of the immune cells, and free FAs are produced and secreted during the activation of these cells. A number of intervention studies regarding the effects of the amount and composition of dietary fat on human immune response have been conducted, results of which are discussed in the following sections. 

Obarzanek E, Hunsberger SA, Van Horn L, et al. Safety of a fat-reduced diet The Dietary Intervention Study in Children (DISC). Pediatrics 1997 99 687-694. 

Chlebowski, R.T. G.L. Blackburn CA. Thomson D.W. Nixon A. Shapiro M.K. Hoy M.T. Goodman A.E. Giuliano N. Karanja P. McAndrew, et al. Dietary fat reduction and breast cancer outcome Interim efficacy results from the womens intervention study./ Natl Cancer Inst. 2006,... 

The discovery that genetic profiles and dietary nutrients interact to determine lipid profiles is exciting, but there is still much to understand about how the multitude of dietary factors interact with specific genotypes to determine plasma lipid profile and other determinants of cardiovascular disease risk. Furthermore, the mechanism by which dietary fat interacts with the LIPC-514C/T polymorphism remains unknown. This study provides a plausible explanation for the intoindividual variability in HDL-C response to dietary intervention observed anecdotally and in well-designed studies. 

Estimates of current fat intakes are considered to have high contents of saturated and PUFA and a high n-6 to n-3 PUFA ratio (Table 13.15). Recommendations have been made to reduce total fat, saturated fats, and decrease the n-6 to n-3 PUFA ratio from 9/1 to 3/1. More recently, dietary guidelines have been made from various international task forces on the basis of both epidemiological and intervention studies in humans (Table 13.16). They recommend consuming ... 

Other dietary factors implicated in prostate cancer include retinol, carotenoids, lycopene, and vitamin D consumption.5,6 Retinol, or vitamin A, intake, especially in men older than age 70, is correlated with an increased risk of prostate cancer, whereas intake of its precursor, [3-carotene, has a protective or neutral effect. Lycopene, obtained primarily from tomatoes, decreases the risk of prostate cancer in small cohort studies. The antioxidant vitamin E also may decrease the risk of prostate cancer. Men who developed prostate cancer in one cohort study had lower levels of l,25(OH)2-vitamin D than matched controls, although a prospective study did not support this.2 Clearly, dietary risk factors require further evaluation, but because fat and vitamins are modifiable risk factors, dietary intervention may be promising in prostate cancer prevention. 

A critical question concerns the possible value of dietary intervention as a preventive or therapeutic measure. There is little doubt that fat intake influences breast cancer development in rodents at levels which are found in the human diets. However, conclusive evidence is lacking about the quantitative and qualitative aspects of these processes and how fat in diets may be modified to reduce human cancer incidence. It is likely that dietary intervention may prove useful initially as a preventive or therapeutic measure in isolated groups of high risk individuals. As genetic, hormonal, and immunologic risk factors became more clearly defined, individuals at high risk and those with breast cancer may benefit from therapeutic low-fat diets whose efficacy will require assessment in well-designed clinical studies. 

There have been three primary and eight secondary prevention trials in which dietary change was the only variable. Dietary modification included reduction in total fat, substitution of saturated fat by polyunsaturated oils and reduction in cholesterol intake. These changes resulted in a reduction of saturated fat intake by 27 55% and reductions in plasma cholesterol of up to 18%. However, with the exception of one study, the Lyon Diet Heart Study (de Lorgeril et al., 1994), neither total or CHD mortality was lowered significantly by the dietary interventions (Ravnskov, 1998 Parodi, 2004). In the successful Lyon Diet Heart Study, a Mediterranean-type diet was compared with the usual post-infarct prudent diet. Throughout this trial, plasma cholesterol levels were similar in both the treatment and control groups. 

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