Influences of "normal" and "prudent" diets on biliary and serum lipids in healthy women

The differential effect of two diets, taken in synchrony with the menstrual cycles for 2 wk each, on serum and bile lipids was investigated in young healthy women. The "normal" diet was high in cholesterol and total fat, and low in polyunsaturated fat and fiber; the "prudent" diet contained a high proportion of polyunsaturated fat and fiber, but was low in cholesterol and total fat; there was little difference in energy content. Both in whole serum and in low-density lipoprotein the concentrations of cholesterol and apolipoprotein B were almost 30% lower with the "prudent" than with the "normal" diet; HDL-cholesterol was 16.3% lower. Triglycerides were increased, only in the very-low-density lipoproteins while cholesterol and apolipoprotein B did not change much in this fraction. The risk to acquire cholesterol gallstones was not less with the use of the "prudent" diet as originally expected. While using the "prudent" diet five of the women had slightly higher lithogenic indices, in two there were much higher values (greater than 25%), and only in three the lithogenic index was unchanged or slightly lower than with the "normal" diet.     

Sterol excretion and cholesterol absorption in diabetics and nondiabetics with and without hyperlipidemia

Fecal neutral and acidic sterols and cholesterol absorption were measured in 12 normal control subjects, 40 diabetic subjects with and without hyperlipidemia, and 27 subjects with hyperlipidemia but without diabetes mellitus. All subjects were on a low-cholesterol diet (less than 300 mg cholesterol/day). Fecal excretion of neutral and acidic sterols was increased in patients with hypertriglyceridemia and was more marked in diabetic patients with hypertriglyceridemia. Cholesterol absorption was decreased in diabetic patients with hypertriglyceridemia. Otherwise, there were no significant differences in sterol excretion or cholesterol absorption in diabetic and nondiabetic subjects compared with control groups with similar lipid levels. The best predictors of fecal neutral- and acidic-sterol excretion and of estimated cholesterol synthesis were very low [corrected]-density lipoprotein triglycerides and high-density lipoprotein cholesterol. Correction of hyperlipidemia may be beneficial in decreasing cholesterol synthesis and, thereby, in decreasing the risk of atherogenesis.     

Fiber digestibility and breath-hydrogen excretion in subjects consuming rural and urban Mexican diets.

Apparent digestibility of dietary fiber and its effect on breath-hydrogen excretion and gastrointestinal symptoms were determined in 16 subjects consuming a plant-based rural Mexican diet (RMD) and a more refined urban Mexican diet (UMD). Neutral-detergent-fiber intake and digestibility were 40.2 and 22.7 g/d (56%) for the RMD and 12.1 and 8.9 g/d (70%), respectively, for the UMD. Apparent digestibilities of hemicellulose, cellulose, and lignin were 40%, 63%, and 53% from the RMD and 73%, 75%, and 58%, respectively, from the UMD. Total breath-hydrogen excretion during 10 postprandial h was similar after both diets, showing that the breath-hydrogen test is of limited value for comparing carbohydrate fermentation from mixed diets. Mouth-to-colon transit time was 5.7 and 6.5 h for the RMD and UMD, respectively (P less than 0.05). There were significantly more gastrointestinal symptoms with the RMD (P less than 0.01); however, neither diet caused symptoms indicative of serious gastrointestinal discomfort.     

Change of urinary nitrogen excretion in response to low-protein diets in adults.

Data from nitrogen balance studies in young men and elderly women were analyzed for the pattern of urinary nitrogen excretion after the subjects had changed from an adequate to an essentially protein-free diet. The single exponential equation: y = P1e-p2t+P3, provided an adequate fit of the data, suggesting that a single-pool model describes the adaptive decline in urinary nitrogen excretion under these dietary conditions. Comparisons of the estimated parameters showed that the fractional rate constant, P2, was the same for both the young men and elderly women, but that the other coefficients differed between the two groups depending upon whether they were expressed per day, per kg of body weight, per unit creatinine excreted, or per kg of body cell mass. The length of time between the change in diet and the attainment of a new equilibrium in urinary nitrogen excretion (ts, or time to stability) is defined as ts = 1/p2 loge(p1/s) where s is the standard error of the fit. The average time to stability was the same in both groups (4.5 days), and 95% of the subjects reached the new equilibrium in nitrogen output within 8 days.     

Components of nitrogen excretion in hospitalised adult patients on intravenous diets

The components of N excretion of 260 adult patients and 37 normal subjects receiving all nutrition intravenously were analysed retrospectively. The 237 patients studied at Columbia University, were classified as nutritionally depleted (67), post-operative (96), injured (43), and septic (31). Twenty-three septic patients were studied at the University of Toronto. Patient groups were stratified according to diet intake. Urinary urea N varied markedly with both diet and disease status. There was marked individual variability, coefficients of variation of about 40%, precluding estimates from diet and disease status alone. Non-urea excretion, in urine, stool and drainages, was markedly affected by disease status but unaffected by diet. Individual variability was proportionally as high as for urea. Nevertheless, since non-urea N is much smaller, estimates of non-urea N together with measurement of urea excretion may be useful for both research and clinical purposes. Estimates given are based on values for urinary non-urea N, stool, and, when present, diarrhoea and drainage, and also provide an estimate of probable error. Since the estimates are based on data from subjects receiving intravenous nutrition and vary with disease status, they are more accurate for similar patients on similar diets than estimates, currently in use, based on urine and stool measurements of normal subjects on oral diets.     

Caffeine consumption and vegetarian diets affect D-glucaric acid excretion in man

The urinary excretion of D-glucaric acid (DGA) has been used as a nonspecific measure of the induction of hepatic enzymes associated with drug metabolism in man. A survey of 124 nonmedicated men (18–56 years of age), who kept a 5-day food, beverage, and drug intake record and collected their total urinary output for the last three days of the five, was conducted to assess the relationship between DGA excretion and various dietary factors. Eighteen nonmedicated healthy women collected the same data, but started on the eighth day from the commencement of menstruation. DGA was determined by an enzymatic assay and recorded as umoles D-glucaro-1,4-lactone/g creatinine. A positive association was found between total DGA excreted and the use of marijuana, caffeine, and tobacco products, the heaviest users excreting higher levels of urinary DGA than the moderate or low users of the same substance (P<0.05). Analysis of variance of mean DGA excretion also revealed differences (P<0.05) between females (17.0±3.7) and males (14.3±5.2); male vegetarians (17.4±5.5) and nonvegetarians (13.9±5.1); and female vegetarians (19.8±4.6) and nonvegetarians (16.2±3.1). Ethanol consumption did not relate to increased DGA excretion in either sex. Multiple regression analysis revealed that vegetarianism and caffeine consumption were the two strongest predictors of DGA excretion accounting for 32 percent of the total variance (P<0.005), while ethanol and marijuana consumption affected DGA the least. These results indicate that dietary and environmental factors may cause important changes in DGA excretion, and these changes may identify dietary inducers of hepatic enzymes associated with drug, xenobiotic and carcinogen biotransformations in humans.     

Short-term effect of two cholesterol-lowering diets on sterol excretion in ileostomy patients

The effect of two cholesterol-lowering diets (PUFA, LO) on the excretion of bile acids and neutral sterols, measured by GLC, was studied in six healthy ileostomates. The reference diet contained 100 g of fat and 13 g of dietary fiber. PUFA was increased in polyunsaturated fatty acids but fat level remained the same. LO was reduced in total fat with a concomitant increase in dietary fiber. Bile acid, net cholesterol, and net sterol excretion increased by 22%, 28%, and 24% (p less than 0.01), respectively, on PUFA. On LO, net cholesterol and net sterol excretion increased by 27% and 18% (p less than 0.01), respectively. Results support the concept of changes in sterol excretion as a mechanism for changes in blood-lipid levels induced by cholesterol-lowering diets.     

Effect of corn and sorghum diets in N1 methylnicotinamide excretion and hepatic enzymes in rats.

This study was carried out to compare the effects of corn (Zea mays) and sorghum (Sorghum vulgare) diets on urinary N1 methylnicotinamide (N'MN) excretion and on the activity of hepatic enzyme in young adult rats. Thirty rats, weighing an average of 174.3 g at the beginning of the experiments, were divided into three groups and studied for 13 weeks. The two experimental diets supplied 7% protein, and a casein diet was used as control. Niacin was excluded from the vitamin mixture used in the corn and sorghum diets. The activities of the following enzymes were studied: betaHOB-D, G6P-D, NADH2-TR, NADPH2-TR, and 3 HOA-0. Urinary excretion of N'MN was statistically different among the three groups, the corn group having the lowest level. The corn-fed animals appeared to have more obvious alterations in liver enzyme activity. The changes found in corn and sorghum-fed animals are different and cannot be explained as due to niacin deficiency. The different amino acid compositions of the two grains and their relationship with the discrepancies in the result are also discussed.     

Weight reduction on lactovegetarian and mixed diets. Changes in weight, nutrient intake, skinfold thicknesses and blood pressure

The purpose of this study was to investigate whether a weight reduction programme based on a lactovegetarian diet has any beneficial effects on the weight, nutrient intake, blood pressure and skinfold thickness of overweight subjects compared with a programme based on a balanced mixed diet. The subjects consisted of three groups of moderately overweight persons, with a mean age of 38 years and a mean overweight of 38 per cent. Two groups had a weight reduction programme for 1 year; group 1 (n = 31) had a 1200 kcal lactovegetarian diet and group 2 (n = 37) had an isocaloric mixed diet. Group 3 (n = 42) served as a control group which had no intervention. During the 1-year study period, group 1 lost 9.2 kg in weight, group 2 lost 10.4 kg and group 3 gained 1.6 kg in weight. Weight loss in both weight reduction groups was accompanied by a reduction in blood pressure, skinfold thickness and arm circumference. The results were slightly more favourable in the mixed diet group than in the lactovegetarian group. In the lactovegetarian group 7 persons were not able to follow the lactovegetarian diet throughout the whole year but ate some meat, fish and eggs during the latter part of the study year. The intake of fibre, vitamin C and calcium was greater and the intake of fat lower in the lactovegetarian than in the mixed diet group during the 1-year weight reduction period. The intake of most nutrients was above the recommended level in both weight reduction groups. The intake was somewhat below recommendations for niacin in the lactovegetarian group, for calcium in the mixed diet group and for iron for women in both groups. It seems desirable to recommend a low-calorie nutritionally well-balanced mixed diet, based on familiar foods and rich in vegetables, instead of a lactovegetarian diet, for long-term weight reduction of overweight persons. In the long term some nutrients may need to be supplemented in both diets.     

Effects of low fat diets varying in P/S ratio on nutrient intakes, fecal excretion, blood chemistry profiles, and fatty acids of adult men

Twenty-three apparently healthy volunteers aged 35 to 60 years consumed closely monitored self-selected (SS) diets for five weeks followed by two low fat controlled diets (25% energy) for two six-week periods followed by another five-week SS diet. The two low fat diets, fed in a crossover design to one-half of the subjects per controlled diet period, had a polyunsaturated/saturated (P/S) fat ratio of either 0.3 or 1.0. Results are reported for bi-weekly measurements of energy and nutrients; blood profiles and plasma fatty acids; and for end-of-period values for stool characteristics. Blood chemistry profiles differed in the two groups. The low P/S diet produced significant increases not only in cholesterol, but in 16:0, 16:1, and percent saturated fatty acids and decreases in 18:2 and omega 6 fatty acids. The reverse was seen with the high P/S diet. The essential fatty acid (EFA) linoleic acid returned in the poststudy period to prestudy levels (all subjects), but arachidonic acid did not. The explanation for negative correlation between magnesium intake or excretion and percent plasma linoleic acid must await further research.     

Chromium intake, absorption and excretion of subjects consuming self-selected diets

Chromium (Cr) content of the self-selected diets of 10 adult males and 22 females was determined. Each subject collected duplicate food and beverage samples on a daily basis for seven consecutive days. The 7-day average intake for males was 33 +/- 3 micrograms (mean +/- SEM), range 22-48 micrograms, and intake for females was 25 +/- 1, range 13-36. Mean Cr intake per 1000 cal was approximately 15 micrograms. Approximately 90% of the diets analyzed were below the minimum suggested safe and adequate daily intake for Cr of 50 micrograms. Chromium absorption was inversely related to dietary intake; absorption at a dietary Cr intake of 10 micrograms was approximately 2% and, with increasing intake to 40 micrograms, Cr absorption decreased to 0.5%. These data demonstrate that the average daily intake of chromium from self-selected diets is well below the minimum suggested safe and adequate intake and that Cr absorption, at levels found in typical US diets, is inversely related to dietary intake.     

Studies of women eating diets with different fatty acid composition. I. Plasma lipoproteins and steroid excretion.

Moderate changes in dietary fat composition have been recommended to improve plasma cholesterol status. Such changes have not been studied extensively in women. This research evaluates plasma lipoprotein and steroid excretion changes in young women who consumed a diet similar to US average consumption in 1974 [40 en% fat, polyunsaturated (P) to saturated fatty acid (S) ratio, P/S = 0.3, US74] or a diet modified to contain 30 en% fat, P/S = 1.0 (MOD). Following a preexperimental period of self-selected diets, young women were fed the diets for 28-day periods in a crossover design with 10 women at the University of Nebraska, Lincoln, and 10 at Iowa State University, Ames. Plasma lipoproteins and steroid excretion were quantitated and the compositions determined. Data were analyzed for race (five Chinese, 14 Caucasians) and for diet carryover effects, as well as for primary diet effects. In the Chinese women, the US74 diet raised total and very-low-density lipoprotein (VLDL) cholesterol compared to prior self-selected or modified diets; in the Caucasian women the MOD diet lowered total, low-density lipoprotein (LDL), and VLDL cholesterol. The diet carryover was evident in total high-density lipoprotein (HDL) and HDL3 cholesterol. Total HDL and HDL3 cholesterol in response to the US74 diet were unchanged from the MOD diet when the US74 diet followed the MOD diet, but were lower than modified when the US74 diet followed self-selected diets. The US74 diet resulted in greater neutral sterol excretion than the MOD diet; this response was more marked in the self-selected, US74, MOD sequence than in the self-selected, MOD, US74 sequence.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiovascular disease risk factors in free-living men: comparison of two prudent diets, one based on lactoovovegetarianism and the other allowing lean meat

In general, vegetarians have lower serum lipids and blood pressures than omnivores have. We tested the blood pressure and serum lipid lowering effects of two fat-modified diets differing primarily in their source of protein. Twenty-six men were randomized in an incomplete block design to two of three diets: a high-fat diet, a fat-modified lactoovovegetarian diet (LOV) and a diet in which 60% of plant protein in the LOV was replaced with lean meat (LM). Compared with the high-fat diet both prudent diets significantly lowered blood pressure, serum total cholesterol (TC), and LDL cholesterol but significantly increased serum triglycerides. The LOV diet had a significantly greater cholesterol-lowering effect than did the LM diet (10% vs 5% decrease) but blood pressure reductions were similar. The partial substitution of lean meat for plant protein in a fat-modified diet did not negate the overall cardiovascular-risk lowering of the lactoovovegetarian diet.     

A nutrient analysis of students' diets in the State of Hawaii

As part of a comprehensive nutrition education needs assessment, we collected, by a modified 24-hour recall method, data on the nutritional quality of diets of a representative sample of 890 students in the state of Hawaii. In general, the nutritional quality of diets decreased as the students got older. Large proportions of students reported daily intake of less than two-thirds of the Recommended Dietary Allowances for iron, calcium, vitamin A, thiamin, and vitamin C. We also found high intakes of sodium, cholesterol, and saturated fatty acids and relatively high energy contribution from snacks and high-sugar foods. These data document the need for nutrition education for the school children in Hawaii and provide important baseline food selection information for designing a nutrition education program for the specific target audience.