Protein intake and urinary excretion of protein-derived metabolites in aging female vegetarians and nonvegetarians

Position of the American Dietetic Association and Dietitians of Canada: vegetarian diets

It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases. Approximately 2.5% of adults in the United States and 4% of adults in Canada follow vegetarian diets. A vegetarian diet is defined as one that does not include meat, fish, or fowl. Interest in vegetarianism appears to be increasing, with many restaurants and college foodservices offering vegetarian meals routinely. Substantial growth in sales of foods attractive to vegetarians has occurred and these foods appear in many supermarkets. This position paper reviews the current scientific data related to key nutrients for vegetarians including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, n-3 fatty acids, and iodine. A vegetarian, including vegan, diet can meet current recommendations for all of these nutrients. In some cases, use of fortified foods or supplements can be helpful in meeting recommendations for individual nutrients. Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life-cycle including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fibre, magnesium, potassium, folate, antioxidants such as vitamins C and E, and phytochemicals. Vegetarians have been reported to have lower body mass indices than non-vegetarians, as well as lower rates of death from ischemic heart disease, lower blood cholesterol levels, lower blood pressure, and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer. While a number of federally funded and institutional feeding programs can accommodate vegetarians, few have foods suitable for vegans at this time. Because of the variability of dietary practices among vegetarians, individual assessment of dietary intakes of vegetarians is required. Dietetics professionals have a responsibility to support and encourage those who express an interest in consuming a vegetarian diet. They can play key roles in educating vegetarian clients about food sources of specific nutrients, food purchase and preparation, and any dietary modifications that may be necessary to meet individual needs. Menu planning for vegetarians can be simplified by use of a food guide that specifies food groups and serving sizes.

Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets

It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases. Approximately 2.5% of adults in the United States and 4% of adults in Canada follow vegetarian diets. A vegetarian diet is defined as one that does not include meat, fish, or fowl. Interest in vegetarianism appears to be increasing, with many restaurants and college foodservices offering vegetarian meals routinely. Substantial growth in sales of foods attractive to vegetarians has occurred, and these foods appear in many supermarkets. This position paper reviews the current scientific data related to key nutrients for vegetarians, including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, n-3 fatty acids, and iodine. A vegetarian, including vegan, diet can meet current recommendations for all of these nutrients. In some cases, use of fortified foods or supplements can be helpful in meeting recommendations for individual nutrients. Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits, including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fiber, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals. Vegetarians have been reported to have lower body mass indices than nonvegetarians, as well as lower rates of death from ischemic heart disease; vegetarians also show lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer. Although a number of federally funded and institutional feeding programs can accommodate vegetarians, few have foods suitable for vegans at this time. Because of the variability of dietary practices among vegetarians, individual assessment of dietary intakes of vegetarians is required. Dietetics professionals have a responsibility to support and encourage those who express an interest in consuming a vegetarian diet. They can play key roles in educating vegetarian clients about food sources of specific nutrients, food purchase and preparation, and any dietary modifications that may be necessary to meet individual needs. Menu planning for vegetarians can be simplified by use of a food guide that specifies food groups and serving sizes.

Anthropometry-based reference values for 24-h urinary creatinine excretion during growth and their use in endocrine and nutritional research

BACKGROUND

Urinary creatinine reference values that take anthropometric data into account, which is mandatory during growth, are not available for healthy white children.

OBJECTIVE

We sought to establish anthropometry-based reference values for 24-h urinary creatinine excretion in healthy white children aged 3-18 y.

DESIGN

Anthropometric variables and 24-h urinary creatinine excretion rates were determined cross-sectionally (225 boys and 229 girls). Age and sex dependency of 24-h creatinine excretion (crude and related to individual anthropometric variables) were assessed to derive appropriate creatinine reference values. The applicability of these creatinine reference values for estimation of daily excretion of certain analytes was assessed in 40 additional children.

RESULTS

Sex-specific, body-weight-related creatinine reference values were derived for the following age groups: 3, 4-5, 6-8, 9-13, and 14-18 y. The 5th percentile exceeded 0.1 mmol x kg(-1) x d(-1) in all age groups >3 y. The use of these creatinine reference values for estimating average 24-h excretion rates of certain analytes (determined as the ratio of analyte to creatinine in spot urine samples) yielded reasonable estimates of mean 24-h urinary excretion rates actually analyzed (spot and 24-h urine samples from the same children). Ideal 24-h creatinine excretion values for height were also derived for a potential determination of the creatinine height index.

CONCLUSIONS

Established anthropometry-based creatinine reference values are recommended as a convenient, simple tool to 1) identify severe 24-h urine collection errors, 2) calculate average 24-h excretion rates of certain analytes (from respective ratios of analyte to creatinine) determined in spot urine samples, and 3) assess somatic protein status by determining the creatinine height index.

Supplemental creatine may decrease serum homocysteine and abolish the homocysteine 'gender gap' by suppressing endogenous creatine synthesis

Creatine synthesis is responsible for the large majority of the methyl group transfers in normal hepatic metabolism, and is significantly greater in men than in women. Since methyl group depletion impairs the efficiency of homocysteine disposal, it is believed that the comparatively high rate of creatine synthesis in men is primarily responsible for the 'gender gap' in homocysteine levels. Adequate supplemental intakes of creatine can suppress creatine synthesis by inhibiting expression of the enzyme arginine-glycine transamidase. Thus, it is proposed that creatine supplementation may represent a practical strategy for decreasing plasma homocysteine levels.

Choices for achieving adequate dietary calcium with a vegetarian diet

To achieve adequate dietary calcium intake, several choices are available that accommodate a variety of lifestyles and tastes. Liberal consumption of dairy products in the diet is the approach of most Americans. Some plants provide absorbable calcium, but the quantity of vegetables required to reach sufficient calcium intake make an exclusively plant-based diet impractical for most individuals unless fortified foods or supplements are included. Also, dietary constituents that decrease calcium retention, such as salt, protein, and caffeine, can be high in the vegetarian diet. Although it is possible to obtain calcium balance from a plant-based diet in a Western lifestyle, it may be more convenient to achieve calcium balance by increasing calcium consumption than by limiting other dietary factors.

The impact of dietary protein intake on urinary creatinine excretion in a healthy pediatric population

OBJECTIVE

The aim of the study was to investigate the effect of daily protein intake on urinary creatinine (CR) excretion in healthy children.

METHODS

In a cross-sectional study, 24-hour urinary CR excretion rates were measured in 350 children aged 4 to 13 years. Body composition was assessed according to anthropometric measurements, and intake of protein was estimated from dietary records.

RESULTS

CR excretion adjusted for fat-free mass (FFM) showed a strong age dependency and correlated clearly with total protein intake and animal protein intake. Stepwise regression analyses revealed that age was the main predictor; however, animal protein intake improved the proportion of explained variance in FFM-related CR excretion. Comparisons of urinary CR output in subgroups of children with low (1st tertile) or high (3rd tertile) animal protein intake showed that on average, a difference of about 9% in CR excretion corresponded to a difference of 1.1 g/kg of body weight per day of animal protein intake.

CONCLUSIONS

Animal protein intake must be taken into account when urinary CR output is used for evaluating body composition in children. Additionally, the finding of a clearly stronger increase in urinary CR than in FFM with age offers an explanation for the commonly observed phenomenon of a decreasing ratio of numerous urinary analytes related to CR during childhood.

Relationship between dietary protein intake and serum urea, uric acid and creatinine, and 24-hour urinary creatinine excretion: the BIRNH Study

Relationships between dietary protein intake of a large free-living group and serum creatinine (Cr), urea and uric acid levels have been studied, based on data obtained from the BIRNH (Belgian Interuniversity Research on Nutrition and Health) study. Highly significant correlations were found in both sexes for total protein, as well as for animal and vegetable protein intake. In a subgroup, the relationship between dietary protein intake and 24-hour urinary Cr excretion has also been studied. The range of +/- 2 SD of the mean for total protein and animal and vegetable protein daily intakes resulted in a calculated range of 24-hour Cr excretion of 430, 317 and 209 mg/24 hours in men and of 192, 169 and 125 mg/24 hours in women, respectively. The 24-hour urinary Cr excretion was significantly influenced by both dietary protein and polyunsaturated fat intake.