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Biomedical subjects

C Leitzmann

Publications and source records attributed to C Leitzmann.

At least 19 recordsLinked to original sources
PubMed2006

Dietary intake of vitamin B6 and concentration of vitamin B6 in blood samples of German vegans.

OBJECTIVE: The study aimed to evaluate the dietary vitamin B6 intake and determine the vitamin B6 concentration in blood samples of German vegans. DESIGN AND SETTING: Cross-sectional study with 33 examination sites all over Germany. Subjects Ninety-three vegans (50 females) with a mean (+/- standard deviation (SD)) age of 43.7 +/- 15.7 years who took no vitamin supplements. METHODS: Dietary intake was assed using a semi-quantitative food-frequency questionnaire. Erythrocyte aspartate aminotransferase activity coefficient (EAST-AC) was calculated as the ratio of stimulated (pyridoxal 5'-phosphate added) to unstimulated activity in blood samples that were provided after an overnight fast. RESULTS: Mean +/- SD vitamin B6 intake was 2.83 +/- 0.98 mg day(-1) and mean +/- SD protein intake was 56.6 +/- 21.7 g day(-1). Of the participants 4% showed vitamin B6 intakes lower than daily recommended intakes for Germany, 16% showed EAST-AC > 1.85, and a further 58% showed EAST-AC of 1.5-1-85. Moderate vegans were affected to a lesser extent than strict vegans. None of the established confounders was a significant predictor of EAST-AC. In logistic regression analyses the contribution of nutriments and cereals to pyridoxine intake was the only predictor of EAST-AC classified as < or = 1.85 and > 1.85, respectively. CONCLUSIONS: In spite of the high total intake of vitamin B6, an adequate concentration in blood samples could not be realised for a majority of the participants. Due to the health implications of a marginal pyridoxine status, vegans should be encouraged to include foods with a high bioavailability of pyridoxine, such as beans, lentils and bananas, in the daily diet.

Adult↗
PubMed2005

German vegan study: diet, life-style factors, and cardiovascular risk profile.

BACKGROUND/AIM: Evaluation of cardiovascular risk profile in 154 German vegans. METHODS: Cross-sectional study, Germany. Study instruments: 2 FFQ, 2 questionnaires, analyses of fasting venous blood samples. RESULTS: The total study population had a low BMI (mean: 22.3 kg/m(2)), a moderate blood pressure (mean: 120/75 mm Hg), an extremely low consumption of alcohol (mean: 0.77 g/day) and 96.8% were nonsmokers. Moderate physical activity (PAL) was reported by nearly 50%, whereas 22.7% declared to have a high PAL (>3 h/week). Median triacylglycerol (TG) was 0.81 mmol/l, total cholesterol (TC) was 4.33 mmol/l, HDL was 1.34 mmol/l. The mean TC/HDL-ratio was 3.3. Lipoprotein(a) (Lp(a)) was 8.13 mg/dl, concentrations of >30 mg/dl were prevalent in 25% of the participants. In general, status of folate and pyridoxine were sufficient, while 49.7% showed cobalamin concentrations <150 pmol/l. Plasma homocysteine levels were slightly elevated (median: 12.5 micromol/l). Cobalamin concentration and duration of vegan nutrition were the main determinants of homocysteine in the total study population. CONCLUSION: Although TC and LDL concentrations were favorable, low HDL and elevated homocysteine and Lp(a) concentrations were unfavorable. Overall, these results confirm the notion that a vegan diet is deficient in vitamin B(12), which may have an unfavorable effect on CHD risk.

Adult↗
PubMed2005

Long-term effect of a plant-based diet on magnesium status during pregnancy.

OBJECTIVE: To compare dietary magnesium intake and magnesium concentrations in serum, red blood cells (RBC) and urine during pregnancy of women habitually following a long-term plant-based diet and of women following an average Western (control) diet. DESIGN: Prospective study during pregnancy. SETTING: Giessen, Germany. SUBJECTS: Healthy pregnant women (n=108) in their 9-12th, 20-22nd and 36-38th gestational week habitually following a plant-based diet for more than 3 y or an average Western diet. The vegetarians were subdivided into ovo-lacto vegetarians (n=27) and low-meat eaters (n=43). RESULTS: Significant higher dietary magnesium intakes were observed in pregnant women consuming a plant-based diet (508+/-14 mg/day for ovo-lacto vegetarians, P<0.001 and 504+/-11 mg/day for low-meat eaters, P<0.001) than in pregnant women consuming a control diet (412+/-9 mg/day). Serum magnesium concentrations were similar in all diet groups whereas RBC magnesium was slightly higher in low-meat eaters than in controls (P=0.058). Urinary magnesium excretion was higher in ovo-lacto vegetarians (P=0.023), followed by low-meat eaters (P=0.017) when compared to the control group. During the third trimester of pregnancy, the frequency and the occurrence of calf cramps was lower in the plant-based diet group than in the control group (P=0.004 and 0.008). CONCLUSIONS: Owing to a higher dietary magnesium intake confirmed by higher urinary magnesium excretion, habitual plant-based diets result in a slightly improved magnesium status during pregnancy and reduce the frequency of calf cramps during the third trimester of pregnancy compared to an average Western diet. Therefore, plant-based diets during pregnancy can be recommended with regard to magnesium supply.

Adult↗
PubMed2004

Double-blind, randomized feedback control fails to improve the hypocholesterolemic effect of a plant-based low-fat diet in patients with moderately elevated total cholesterol levels.

OBJECTIVE: To determine whether the cholesterol-lowering effect of a plant-based low-fat diet can be improved by a flexible control design that controls the extent of fat reduction based on the individual response of blood cholesterol. DESIGN: Randomized, double-blind intervention study. SETTING: A hotel in Prerow, Germany. SUBJECTS: A total of 32 participants (21 female and 11 male participants) with total cholesterol level > 5.7 mmol/l. INTERVENTION: The control group consumed a plant-based low-fat diet with constantly 20% of energy as fat; the intervention group received a diet with either 20 or 15% of energy as fat, depending on the serum cholesterol response of the preceding week. A flexible control design based on the individual cholesterol response during a run-in period of 1 week was used within a low-fat intervention. RESULTS: During the run-in period, the consumption of a plant-based low-fat diet led to a reduction in total cholesterol by 18+/-6 mmol/l (P < 0.001), in LDL cholesterol by 19+/-9 mmol/l (P < 0.001) and triglycerides by 13+/-3 mmol/l (P < 0.001). During the feedback control period, an additional reduction in total cholesterol by 13+/-8 (P < 0.001) and in LDL cholesterol by 17+/-11 (P < 0.001) was observed compared to 15+/-15 and 7+/-18 in the control group. The effect of an additional feedback control was only marginal and not statistically significant compared to the effect of the low-fat diet alone. CONCLUSIONS: On a level of fat intake already reduced to 20% of energy, the use of a feedback control to adapt the fat content of the diet depending on the individual serum cholesterol response was not more effective in reducing blood cholesterol levels than a plant-based low-fat diet alone.

Aged↗
PubMed2003

Dietary intakes and lifestyle factors of a vegan population in Germany: results from the German Vegan Study.

OBJECTIVE: Evaluation of dietary intakes and lifestyle factors of German vegans. DESIGN: Cross-sectional study. SETTINGS: Germany. SUBJECTS: Subjects were recruited through journal advertisements. Of 868 volunteers, only 154 participated in all study segments (pre- and main questionnaire, two 9-day food frequency questionnaires, blood sampling) and fulfilled the following study criteria: vegan dietary intake at least 1 year prior to study start, minimum age of 18 y, no pregnancy or childbirth during the last 12 months. INTERVENTIONS: No interventions. RESULTS: All the 154 subjects had a comparatively low BMI (median 21.2 kg/m(2)), with an extremely low mean consumption of alcohol (0.77+/-3.14 g/day) and tobacco (96.8% were nonsmokers). Mean energy intake (total collective: 8.23+/-2.77 MJ) was higher in strict vegans than in moderate ones. Mean carbohydrate, fat, and protein intakes in proportion to energy (total collective: 57.1:29.7:11.6%) agreed with current recommendations. Recommended intakes for vitamins and minerals were attained through diet, except for calcium (median intake: 81.1% of recommendation), iodine (median: 40.6%), and cobalamin (median: 8.8%). For the male subgroup, the intake of a small amount of food of animal origin improved vitamin and mineral nutrient densities (except for zinc), whereas this was not the case for the female subgroup (except for calcium). CONCLUSION: In order to reach favourable vitamin and mineral intakes, vegans should consider taking supplements containing riboflavin, cobalamin, calcium, and iodine. Intake of total energy and protein should also be improved.

Adult↗
PubMed2001

Giessen Wholesome Nutrition Study: relation between a health-conscious diet and blood lipids.

OBJECTIVE: To study in humans the relationship between a diet consistent with most of the current recommendations for the prevention of nutrition-related diseases (Wholesome Nutrition) and the blood lipid profile (total cholesterol, LDL-, HDL-cholesterol, LDL/HDL-ratio, triglycerides). DESIGN: Cross-sectional study with two diet groups. SETTING: Former West Germany. SUBJECTS: Healthy women (n=243, aged 25-65 y) adhering to Wholesome Nutrition for at least 5 y (subdivided into 111 ovo-lacto vegetarians and 132 low-meat eaters) and an according control group of 175 women eating an average German mixed diet. They were all recruited through an advertisement campaign and selected on the basis of their food consumption. RESULTS: Considering potential confounders, the Wholesome Nutrition subgroups had higher HDL-cholesterol levels than the control group. No differences were observed for total cholesterol and LDL-cholesterol. For LDL/HDL-ratio and triglycerides the effect of diet was dependent on interaction terms. With increasing risk factors (age or body mass index (BMI)) the Wholesome Nutrition subgroups showed more favourable blood lipids. CONCLUSIONS: Women eating a preventive diet on a long-term basis exhibit more favourable blood lipid profiles than women consuming an average mixed diet. This is particularly obvious for HDL-cholesterol in the presence of certain risk factors and when an ovo-lacto vegetarian version is practised. SPONSORSHIP: Eden Foundation, Bad Soden, Germany.

Adult↗
PubMed2001

Folate status during pregnancy in women is improved by long-term high vegetable intake compared with the average western diet.

The effect of increasing dietary folate on folate status during pregnancy is controversial. The aim of this study was to compare folate intake and folate status during pregnancy of women with high long-term vegetable intake and those eating an average Western diet. In a prospective study that included 109 participants, pregnant women adhering to a predominant vegetarian diet with high vegetable intake for 8 +/- 0.5 y with subgroups of ovo-lacto vegetarians (n = 27) and low meat eaters (n = 43) and women eating an average Western diet (control group, n = 39) were compared with regard to dietary intake and plasma and red blood cell (RBC) folate concentrations during wk 9-12, 20-22 and 36-38 of gestation. Plasma and RBC folate concentrations were highest in ovo-lacto vegetarians, followed by low meat eaters and lowest in the controls. Ovo-lacto vegetarians and low meat eaters showed a lower risk for folate deficiency, with RBC folate concentrations of <320 nmol/L resulting in odds ratios of 0.10 (95% confidence interval, 0.01-0.56) and 0.52 (95% confidence interval, 0.20-1.34), respectively. In ovo-lacto vegetarians, the RBC folate concentration was positively related to the intake of vitamin B-12 (r = 0.51, P: < 0.0001). The results of the study suggest that long-term high vegetable intake favorably affects plasma folate as well as RBC folate concentrations throughout pregnancy and reduces the risk of folate deficiency if an adequate vitamin B-12 supply is ensured.

Adult↗
PubMed1999

Consequences of a long-term raw food diet on body weight and menstruation: results of a questionnaire survey.

OBJECTIVE: To examine the relationship between the strictness of long-term raw food diets and body weight loss, underweight and amenorrhea. METHODS: In a cross-sectional study 216 men and 297 women consuming long-term raw food diets (3.7 years; SE 0.25) of different intensities completed a specially developed questionnaire. Participants were divided into 5 groups according to the amount of raw food in their diet (70-79, 80-89, 90-94, 95-99 and 100%). A multiple linear regression model (n = 513) was used to evaluate the relationship between body weight and the amount of raw food consumed. Odds of underweight were determined by a multinomial logit model. RESULTS: From the beginning of the dietary regimen an average weight loss of 9.9 kg (SE 0.4) for men and 12 kg (SE 0.6) for women was observed. Body mass index (BMI) was below the normal weight range (<18.5 kg/m(2)) in 14.7% of male and 25.0% of female subjects and was negatively related to the amount of raw food consumed and the duration of the raw food diet. About 30% of the women under 45 years of age had partial to complete amenorrhea; subjects eating high amounts of raw food (>90%) were affected more frequently than moderate raw food dieters. CONCLUSIONS: The consumption of a raw food diet is associated with a high loss of body weight. Since many raw food dieters exhibited underweight and amenorrhea, a very strict raw food diet cannot be recommended on a long-term basis.

Adult↗
PubMed1997

Fuzzy sets and fuzzy decision making in nutrition.

OBJECTIVE: This paper demonstrates that a nutrient intake can be described in a differentiated way and can be evaluated by employing fuzzy decision making. It also examines whether fuzzy decision making can simplify nutrition education by small individual improvements in food selection behaviour. RESULTS: The recommendations for nutrient intakes are presented as fuzzy sets, so that the intake of each nutrient can be evaluated by an objective fuzzy value. The evaluation of the harmonic minimum allows, for the first time, that the fuzzy value of an individual nutrient can be stated as a total value. On the basis of individual nutrition assessment, fuzzy logic in connection with fuzzy decision making, allows optimization of meals considering individual food preferences. This makes it possible in nutrition counselling to improve the nutrient intake markedly with relative small changes in food choice. CONCLUSION: Fuzzy decision making can simplify and optimize nutrition education.

Adult↗
PubMed1996

A rapid mechanical lysing procedure for routine analysis of plasmids from lactobacilli, isolated from sourdoughs.

Variations in cell wall composition of lactobacilli complicate attempts to standardize plasmid detection on the basis of enzymatic lysing procedures. Mechanical disruption of cell walls by a horizontal mixer-mill proved to be more effective, rapid and reproducible. In order to judge the risk of damaging plasmid deoxyribonucleic acids (DNA) in this way, plasmid profiles obtained after enzymatic lysing and mechanical disruption of cell walls were compared. As no differences were detected the mechanical procedure was accepted as a suitable method for routine analysis of plasmid profiles.

Bread↗
PubMed1994

Nutrient intake of endurance runners with ovo-lacto-vegetarian diet and regular western diet.

During an endurance run (1,000 km in 20 days) it was investigated whether an ovo-lacto-vegetarian diet (OLVD) could cover the nutritional requirements of endurance athletes. A regular western diet (RWD) was used as reference. Both diets were offered with an energy content of 4,500 kcal per day and an energy percentage of carbohydrate:fat:protein of 60:30:10. The runners were divided into two dietary groups according to their usual dietary habits. The results of the 55 participants who completed the race show that runners from both groups had the same intake of energy, carbohydrate, fat and protein. Runners of the OLVD group consumed more dietary fiber and polyunsaturated fatty acids as well as less cholesterol. With the exception of sodium chloride and cobalamin, the intake of the calculated minerals and vitamins was higher in the OLVD and exceeded the official recommendations. This study shows that an OLVD with a high nutrient density is adequate to cover the nutritional requirements of endurance-athletes. The intake and absorption of iron should be monitored closely in all diet groups.

Adult↗
PubMed1991

[The body muscle compartment and its relationship to food absorption and blood chemistry during an extreme endurance performance].

The purpose of the study was to examine the changes of the muscle's fat-free compartment and its relation to the corresponding biochemical and nutritional parameters of 42 men and 13 women, the participants of an ultra long-distance run of 1000 km (20 days of daily running 50 km). The muscle-fractions initially increased, decreased in the middle phase, and remained stable for the rest of the run. Significant changes of the fat-free weight were registered from the 11th day on, the LBM decreasing until the middle of the distance; then the lean body mass enlarged. All the muscle-circumferences were reduced with the exception of the thigh, which grew, paralleling the CK/CKMB-concentrations, this phenomenon being due to the high mechanical stress of the lower extremities. The biochemical parameters exhibit a strain-related reaction of adaptation within the initial 6 days, the hormones and protein-concentration increasing in the beginning and falling from the third day on, uric acid and CK/CKMB-activity decreasing from the 6th day on. The consecutive parallel reduction of both uric acid, urea, and muscle measurements might be seen as a special endurance-related clearance-mechanism of potential toxicants. The negative relationship between the changes of muscle measurements and the cumulative protein intake and the catabolic constellation of the clinical-chemical values might suggest that the absolute protein intake of 1.7 g/kg body mass should be increased in order to diminish the loss of musculature during an ultra-long distance run.

Absorption↗
PubMed1989

Effects of an ultra-long-distance (1000 km) race on lipid metabolism.

The influence was examined of ultra-long-distance running (1000 km race lasting 20 days) on changes in serum lipids. The 110 participants received two types of diet, a conventional Western diet and a wholesome vegetarian diet. Of the 55 finishers the serum concentration of total cholesterol, low density lipoprotein (LDL)-cholesterol, apolipoprotein B and triglycerides decreased significantly during the first 8 days of the run, but rose again towards the end of the race without reaching pre-race levels. The high density lipoprotein (HDL)-cholesterol increased initially but decreased in the final days of the run. The values for apolipoprotein A-I were not correlated with HDL-cholesterol. The free fatty acids and free glycerol showed marked increases (five times the prerace concentration), falling towards the end of the run. Changes in serum lipids showed no correlation with changes in body mass. Similar changes were observed in both dietary groups.

Adult↗
PubMed1989

Effects of long-distance running on iron metabolism and hematological parameters.

In 110 well-trained participants of a 1000-km running competition lasting for 20 days hematological parameters, iron metabolism, and their respective changes during the race were investigated. Thirty-nine men and 11 women were accustomed to wholesome vegetarian food (lacto-ovovegetarian), 52 men and 8 women consumed a conventional western diet. In each group 50% of the runners finished the race. Before the competition started red blood cell count, hematocrit, and hemoglobin were on average below the values observed in the normal population in all groups. Both male and female runners consuming the wholesome diet showed significantly lower ferritin values than those on a western diet. During the first days of the competition hemolysis occurred leading to increased serum concentrations of bilirubin and iron and decreased haptoglobin levels. Hb concentrations showed a constant decrease during the race. Serum ferritin concentration rose about twofold within the first days and then decreased again without reaching pre-race levels. Serum iron concentrations showed a significant decrease between days 3 and 6. Iron loss was caused by hematuria (25% of all urines tested), gastrointestinal blood loss (10% of all stool specimens tested), and by sweating (4.5 micrograms iron/dl sweat). Our results suggest that especially in female long-distance runners it may be difficult to supply sufficient quantities of iron with the diet.

Adult↗
PubMed1987

[Blood glucose and insulin levels in healthy persons and diabetics after intake of coarse wholemeal preparations, especially fresh grain muesli].

In a study of seven type II diabetics the effects of the usual diabetic diet were compared with those of a cereal of whole-meal (both having the same energy content and nutrients proportions). The cereal gave a more even blood-glucose curve at a significantly lower level (maximal rise after the first breakfast with the cereal was 20 mg/100 ml, after the usual diabetic breakfast 75 mg/100 ml). In addition, in 12 metabolically healthy persons comparison was made of post-prandial blood-glucose and insulin levels after intake of raw and of heated wheat and corn whole-meal preparations. The raw wheat variant produced much flatter blood-glucose and insulin curves than the heated test meals (maximal rise of blood-glucose 6 vs 27-38 mg/100 ml; blood insulin 8 vs 35-50 microU/ml), while the raw corn (oat) variant achieved only a small flattening of the curve compared with that after the heat-treated preparation. Measurement of H2 exhalation provided no evidence for differential malabsorption between raw and heated test meals. Fresh-corn muesli with unheated wheat whole-meal is suitable in the diet of type II diabetics to counteract high postprandial levels of blood-glucose and thus improve the diabetic metabolic state.

Blood Glucose↗