Ramadan fasting can serve as an excellent research model for the study of human metabolism and behavior. One of the earliest published research findings on Ramadan fasting is from East Pakistan, now Bangladesh, reported by Muazzam and Khaleque (1). During the last twenty years there has been growing realization on the part of many scientists for further research in this area. Recently, a Ramadan fasting model has been used for various metabolic studies, Iraki et al (2), Ayabak et al (3), Husain et al. (4), Malik et al (5), El Ati et al (6), Nomani (7), Nomani et al (8), Sweileh et al (9) and Malhotra eta al (10) and for behavior modification, Afifi (11) Farren and Naidoo (12) and Daradkeh (13).
High blood cholesterol and uric acid have been considered health risk factors in cardiovascular diseases and gout, respectively. Conflicting results have been reported on the effect of dietary fat on changes in blood cholesterol levels, Gurr et al (14) and Kritchevsky (15). In 1979, Nomani et al (16) hypothesized that there is an increase in blood cholesterol levels with either increasing or decreasing level of energy intake in relation to the requirement. The recent findings of Ramadan fasting research, Nomani (7), Nomani et al (8) and Hallak and Nomani (17), confirm the hypothesis and help in resolving the dilemma of conflicting findings. The dietary regulation of blood cholesterol and uric acid levels are not only useful for Muslims but also for others throughout the world, irrespective of religion, race, color, gender or ethnic group.
According to the 1995 dietary guidelines, from the U. S. Department of Agriculture and Department of Health and Human Services (18) - energy from fat should not to be more than 30 percent, a level that is appropriate for the general population; however, this level may be inappropriate during Ramadan fasting or similar restricted energy intake situations. Under restricted energy intake conditions, such as Ramadan fasting, anorexia nervosa, prolonged weight control dieting and low energy intake conditions in underdeveloped or developing countries, there is a need for reassessment.
One of the major problems that contributes to conflicting results on the effect of quantity or quality of dietary fat on blood cholesterol level is a failure to examine the effect of dietary fat in relation to body weight or changes in body weight. There is an increase in blood cholesterol levels with increasing or decreasing weight from normal weight levels. Hallak and Nomani (17) noted increased blood cholesterol level with weight loss during the fasting month of Ramadan. Other investigators also noted increased blood cholesterol level with weight loss, Fedail et al. (19), Shoukry (20) and El Arnaoty and Johnson (21). Among non-Muslim American female subjects there was increase in blood cholesterol level with lowering of the body mass-index below 18.5, Nomani et al. (22). During Ramadan, when no significant difference was noticed in blood cholesterol levels, before and after fasting period, there was no significant difference in body weight as well, Maislos, et al (23).
Dietary fat and blood cholesterol level
Another omitted or insufficiently considered factor is statement of the energy intake in relation to the requirement. Under limited energy intake conditions, several studies on rats and humans, which include Muslims and non-Muslims, have indicated beneficial effects of a high fat-diet. In rats when the energy intake was ~70 percent of the requirement, blood cholesterol level was negatively associated with dietary fat energy, Nomani et al (24). In another study from the same laboratory, Forbes et al (25), found no significant difference in blood cholesterol levels of rats on diet with 40 percent of the total energy intake through fat (corn and coconut oils, 1.4:2) as compared to the group consuming 21 percent fat-energy from corn oil. Total energy intake was around 67-75 percent of the requirement. Further, this study indicates that there was significantly higher, p<0.05, nitrogen retention in the body in the high-fat diet group.
In humans, Murray et al (26) reported no significant difference between the mean blood cholesterol levels of Anagamba nomads, consuming 73% of the energy as fat, mainly from milk, and Kanouri sedentary men, both from East-Niger and of the same genetic stock, consuming only 9% of energy as fat. The total energy intake was around 18,00 kcal/day and mean weight of 52.3 kg and 51.4, respectively. Among Americans, Grundy (27) noted that when body weight was kept constant, a diet rich in monounsaturated fatty acids was as effective in lowering plasma cholesterol as was a diet low in fat and high in carbohydrate.
Hallak and Nomani (17) found that during the last two weeks of Ramadan fasting, when the subjects were on high-fat diets (1834 Kcal/day), there was no significant difference in blood cholesterol levels and body weights from beginning and end of this period. In another Ramadan study, when there was no significant change in body weight, Nomani et al. (8) noted change in serum cholesterol level inversely related to fat energy intake (coefficient of correlation, r = - 0.77, p<0.02). In a concave curve-linear model change in total-cholesterol:HDL-cholesterol ratio was the lowest and optimal at 36 percent of the energy from fat, coefficient of determination, r2 = 0.86, p<0.01. In the multiple regression r2 value further improved (0.98) with the inclusion of total energy intake, change in total-cholesterol:HDL-cholesterol = 4118.28 - 6.009 Fat, g/day - 3.077 Energy, Kcal/day. + 0.0007 Energy (Kcal/day)2, p<0.001, Nomani (7). This suggest that fat and total energy level independently affected changes in the ratio. Maislos, et al (23) found that not only was there no significant difference in blood cholesterol level but the HDL-cholesterol profile improved during the fasting period. The dietary records were not available. However, the authors had the impression that the food consumed during Ramadan was of higher fat and carbohydrate content than that consumed during the rest of the year. In a recent study, El Ati et al. (6) showed that during Ramadan fasting the body develops adaptive mechanisms and there is an increased and decreased oxidation of fat and carbohydrate, respectively.
The findings of the above studies have lead to hypothesize that when energy is a limited, increased dietary fat level favors reduced breakdown of body protein, including labile proteins. Low-density lipoprotein (LDL) cholesterol-receptors , which are protein in nature, also may be affected. Thus, high-fat diet contributes in preventing the elevation of blood cholesterol level at restricted energy conditions, including Ramadan fasting. The findings have probable usefulness not only among Muslims observing Ramadan fast but also non-Muslims with anorexia nervosa, hospital in-patient subjects with low-weight or under-weight, populations in under-developed or developing countries, persons on prolonged low-calorie diets in weight-control programs and in many other situations with restricted energy intake conditions.
Blood Uric Acid
During Ramadan fasting increased blood uric acid have been observed by Fedail et al (19), El Ati et al (6), Gumaa et al (28), Nomani et al (29) and Al-Hader et al (30) . Nomani et al (29) noted change in blood uric levels negatively related to the changes in body weight, r = 0.52, p<0.05. In other words, increase in blood uric acid level was positively associated with body weight loss. During the last two weeks of Ramadan fasting, blood uric acid level in subjects with high uric acid level was prevented from further rise with the inclusion of high-fat diet, Nomani et al (7). Uric acid is a product of purine metabolism. Dietary-fat may be helpful in preventing the catabolism of these nitrogen containing compounds and protein during the fasting period. El Ati et al (6) noted the uric acid level returned back to normal one month after Ramadan period.
The findings of Ramadan fasting among Muslims and similar limiting energy intake situations among non-Muslims suggest that a high-fat diet around 36 percent of energy through fat, which includes poly-unsaturated fat, may be beneficial in preventing elevation of blood cholesterol or uric acid level and better retention of protein in the body.
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International Journal of Ramadan Fasting Research
M. Z. A. Nomani, Ph. D.