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Biomedical subjects

Susan I Barr

Publications and source records attributed to Susan I Barr.

27 records · Page 2Linked to original sources
PubMed2003

Increased dairy product or calcium intake: is body weight or composition affected in humans?

To assess the possible impact of increased intakes of dairy products or calcium on body weight or composition, a MEDLINE search was conducted to identify randomized trials of supplementation with calcium or dairy products. Nine studies of dairy product supplementation were located: In seven, no significant differences in the change in body weight or composition were detected between treatment and control groups. However, two studies conducted in older adults observed significantly greater weight gain in the dairy product groups. The interpretation of these findings is complicated by the inability to accurately determine the extent of dietary compensation for the increment in energy intake provided by the added dairy products. This is not an issue in the interpretation of studies of calcium supplementation, of which 17 were identified. Only one study found greater weight loss in the supplemented group; in the remaining studies, changes in body weight and/or body fat were strikingly similar between groups. In conclusion, the data available from randomized trials of dairy product or calcium supplementation provide little support for an effect in reducing body weight or fat mass. However, the studies reviewed were not specifically designed or powered to address this issue; such studies are required.

Adult↗
PubMed2003

Planning diets for individuals using the dietary reference intakes.

Dietary Reference Intakes (DRIs) are now available for energy, macronutrients, fiber, vitamins, and minerals, and can be used to plan diets for individuals. This article defines the four DRIs (the Estimated Average Requirement, the Recommended Dietary Allowance, the Adequate Intake, and the Tolerable Upper Intake Level), and describes two other reference standards--the Estimated Energy Requirement and the Acceptable Macronutrient Distribution Range. Planning diets for individuals involves identifying the appropriate nutrient intake goals, translating the nutrient goals into food intake (and supplement use, if warranted), assessing the plan, and revising it if required. This process is illustrated using case studies of a female vegetarian marathon runner and an older male smoker.

Age Factors↗
PubMed2003

Protein and bone health: literature review and counselling implications.

For decades, public health promotion campaigns on bone health have emphasized the importance of adequate calcium and vitamin D intakes, as well as weight-bearing physical activity. However, no obvious consensus has emerged on the role of dietary protein. To identify what agreement does exist in the literature, in this article we review the theoretical basis for protein's role in bone health, assess some recent cross-sectional and prospective studies, and generate recommendations for practice. There is general agreement in the literature that higher protein intake increases urinary calcium loss; the body compensates for this loss by increasing calcium absorption in the gut, providing that calcium intake is sufficient. A possible explanation for calcium loss, the "acid-ash" hypothesis, is discussed, and suggestions are made about food choices that may counter the calciuric effect of protein. A survey of cross-sectional and prospective studies shows equivocal results, with confounding variables complicating the analysis. Both deficient and excessive protein intakes have been shown to affect bone health negatively, although lower and upper thresholds have not been determined. Practical advice on achieving bone health is given, with an emphasis on the use of Canada's Food Guide to Healthy Eating in setting dietary goals.

Bone and Bones↗
PubMed2002

Perceptions and practices of self-defined current vegetarian, former vegetarian, and nonvegetarian women.

OBJECTIVE: To assess the diversity of vegetarians' dietary practices and how they change over time, and to explore perceptions of meat and dairy products among vegetarians, former vegetarians, and nonvegetarians. DESIGN: Cross-sectional survey; qualitative interviews with a subsample. SUBJECTS/SETTING: Ninety self-defined current vegetarian, 35 former vegetarian and 68 nonvegetarian women in Vancouver, British Columbia. A subsample of 15 subjects completed qualitative interviews. STATISTICAL ANALYSIS PERFORMED: Group comparisons using 1-way analysis of variance with post-hoc testing for continuous variables, chi2 for categorical variables. RESULTS: Of 90 current vegetarians, 51 and 14 reported occasional use of fish or chicken respectively. Fifty-six vegetarians, including 4 of 6 vegans, reported that their diets had become more restrictive over time, and 48 planned additional changes, most frequently a reduction in dairy product use. Reasons cited by former vegetarians for resuming omnivorous diets included: not feeling healthy, concern about their nutritional status, a change in living situation, or missing the taste of meat. Perceptions of meat and dairy products differed significantly by dietary pattern: nonvegetarians and former vegetarians were more likely than current vegetarians to agree with statements inferring positive attributes (eg, nutrient content). In contrast, more current and former vegetarians than nonvegetarians agreed with statements inferring negative attributes (eg, presence of contaminants). APPLICATIONS/CONCLUSIONS: Dietitians who counsel women need to be aware of the heterogeneity of dietary practices and beliefs regarding use of animal products to provide advice appropriate to each individual. At a broader level, addressing women's food safety and animal welfare concerns will likely require collaboration among food industry and government, health, and consumer agencies.

Adult↗
PubMed2002

Interpreting and using the dietary references intakes in dietary assessment of individuals and groups.

For individuals, a statistical approach is available to compare observed intakes to the EAR or AI (to assess adequacy), and the UL (to assess risk of excess). A more qualitative assessment of intakes involves comparison directly to the RDA to evaluate adequacy, but this is accurate only if long-term usual intake is known. For groups of people, the prevalence of inadequacy can usually be estimated as the proportion with intakes below the EAR, while the prevalence of potentially excessive intakes is estimated as the proportion above the UL. The accuracy of all assessments depends on unbiased and accurate intake estimates as well as a consideration of the effects of day-to-day variation in intake. Nutrition practitioners will find the new DRIs useful for assessing diets in a variety of settings. Computerized assessment systems will be important tools when incorporating these theoretical concepts into dietetic practice.

Binomial Distribution↗
PubMed2002

Using the new dietary reference intakes to assess diets: a map to the maze.

New Dietary Reference Intakes (DRIs) are being set by the Institute of Medicine, and represent a new way of defining nutrient intake recommendations. For the first time, the recommendations for the United States and Canada allow the calculation of the probability of adequacy for an individual, and the prevalence of inadequacy for a population. In addition, possible excessive consumption of many nutrients can be evaluated. The goal of this review is to provide a practical guide to the proper uses of the new DRIs when assessing intakes.

Child↗
PubMedDate not supplied

Nutritional considerations for vegetarian athletes.

With the growing interest in the potential health benefits of plant-based diets, it is relevant to consider whether vegetarian dietary practices could influence athletic performance. Accordingly, this review examines whether nutrients that may differ between vegetarian and omnivorous diets could affect physical performance. We also describe recent studies that attempt to assess the effects of a vegetarian diet on performance and comment on other nutritional aspects of vegetarianism of relevance to athletes. Although well-controlled long-term studies assessing the effects of vegetarian diets on athletes have not been conducted, the following observations can be made: 1) well-planned, appropriately supplemented vegetarian diets appear to effectively support athletic performance; 2) provided protein intakes are adequate to meet needs for total nitrogen and the essential amino acids, plant and animal protein sources appear to provide equivalent support to athletic training and performance; 3) vegetarians (particularly women) are at increased risk for non-anemic iron deficiency, which may limit endurance performance; and 4) as a group, vegetarians have lower mean muscle creatine concentrations than do omnivores, and this may affect supramaximal exercise performance. Because their initial muscle creatine concentrations are lower, vegetarians are likely to experience greater performance increments after creatine loading in activities that rely on the adenosine triphosphate/phosphocreatine system. 5) Coaches and trainers should be aware that some athletes may adopt a vegetarian diet as a strategy for weight control. Accordingly, the possibility of a disordered eating pattern should be investigated if a vegetarian diet is accompanied by unwarranted weight loss.

Adolescent↗