Connie M. Weaver

Evaluation, Treatment, and Prevention of Vitamin D Deficiency: an Endocrine Society Clinical Practice Guideline

OBJECTIVE The objective was to provide guidelines to clinicians for the evaluation, treatment, and prevention of vitamin D deficiency with an emphasis on the care of patients who are at risk for deficiency. PARTICIPANTS The Task Force was composed of a Chair, six additional experts, and a methodologist. The Task Force received no corporate funding or remuneration. CONSENSUS PROCESS Consensus was guided by systematic reviews of evidence and discussions during several conference calls and e-mail communications. The draft prepared by the Task Force was reviewed successively by The Endocrine Societys Clinical Guidelines Subcommittee, Clinical Affairs Core Committee, and cosponsoring associations, and it was posted on The Endocrine Society web site for member review. At each stage of review, the Task Force received written comments and incorporated needed changes. CONCLUSIONS Considering that vitamin D deficiency is very common in all age groups and that few foods contain vitamin D, the Task Force recommended supplementation at suggested daily intake and tolerable upper limit levels, depending on age and clinical circumstances. The Task Force also suggested the measurement of serum 25-hydroxyvitamin D level by a reliable assay as the initial diagnostic test in patients at risk for deficiency. Treatment with either vitamin D(2) or vitamin D(3) was recommended for deficient patients. At the present time, there is not sufficient evidence to recommend screening individuals who are not at risk for deficiency or to prescribe vitamin D to attain the noncalcemic benefit for cardiovascular protection.

Peak bone mass.

R. P. Heaney, S. Abrams, B. Dawson-Hughes, A. Looker, R. Marcus, V. Matkovic and C. Weaver Creighton University, Omaha, NE; Children’s Nutrition Research Center, Houston, TX; Tufts University, Boston, MA; National Osteoporosis Foundation, Washington, DC; National Center for Health Statistics, Hyattsville, MD; Stanford University, Palo Alto, CA; Ohio State University, Columbus, OH; and Purdue University, West Lafayette, IN, USA

Guidelines for Preventing and Treating Vitamin D Deficiency and Insufficiency Revisited

Boston University School of Medicine (M.F.H.), Boston, Massachusetts 02118-2526; Osteoporosis Research Program (N.C.B.), University of Wisconsin, Madison, Wisconsin 53706; Department of Rheumatology and Institute for Physical Medicine (H.A.B.-F.), University Hospital Zurich, 8091 Zurich, Switzerland; Divisions of Adolescent Medicine and Endocrinology (C.M.G.), Childrens Hospital, Boston, Massachusetts 02115; Division of Endocrinology and Metabolism (D.A.H.), Health Science Centre, University of Calgary Faculty of Medicine (R.P.H.), Calgary, Canada AB T2N 4N1; Creighton University (R.P.H.), Omaha, Nebraska 68131; Division of Preventative, Occupational, and Aerospace Medicine Mayo Clinic (M.H.M.), Rochester, Minnesota 55905; and Department of Foods and Nutrition (C.M.W.), Purdue University, West Lafayette, Indiana 47907

Dairy Calcium is Related to Changes in Body Composition during a Two-Year Exercise Intervention in Young Women

Objective: Relationships between micronutrients and dairy product intake and changes in body weight and composition over two years were investigated. Design: Two year prospective non-concurrent analysis of the effect of calcium intake on changes in body composition during a two year exercise intervention. Subjects: 54 normal weight young women, 18 to 31 years of age. Measures of Outcome: Mean intakes of nutrients of interest were determined from three-day diet records completed at baseline and every six months for two years. The change in total body weight and body composition (assessed by dual x-ray absorptiometry) from baseline to two years was also determined. Results: Total calcium/kilocalories and vitamin A together predicted (negatively and positively, respectively) changes in body weight (R2 = 0.19) and body fat (R2 = 0.27). Further, there was an interaction of calcium and energy intake in predicting changes in body weight, such that, only at lower energy intakes, calcium intake (not adjusted for energy) predicted changes in body weight. Conclusions: Regardless of exercise group assignment, calcium adjusted for energy intake had a negative relationship and vitamin A intake a positive relationship with two year changes in total body weight and body fat in young women aged 18 to 31 years. Thus, subjects with high calcium intake, corrected by total energy intake, and lower vitamin A intake gained less weight and body fat over two years in this randomized exercise intervention trial.

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.

Calcium and vitamin D

Calcium and vitamin D are essential for bone maintenance and for treatment-induced bone augmentation. Deficiencies of both nutrients are very common in the age group most afflicted by osteoporosis. Calcium enhancement of estrogens effects now have been clearly demonstrated. Additionally, all currently approved bone active agents have been tested only in the presence of extra calcium, and newer anabolic agents create a skeletal need for mineral that will require even higher levels of calcium repletion. Prudent nutritional support for osteoporosis prevention and treatment consists of 30 to 40 mmol Ca/d together with sufficient vitamin D to maintain serum 25(OH)D levels above 80 nmol/L (i.e., approximately 25 microg vitamin D/d).

Absorbability of calcium sources: the limited role of solubility.

SummaryFractional absorption of seven chemically defined calcium sources was measured in normal adult women under standardized load conditions. Solubility of the sources in water at neutral pH ranged from a low of 0.04 mM to a high of 1500 mM. The relationship of solubility to absorbability was weak. In the range from 0.1 to 10 mM, within which most calcium supplement sources fall, there was no detectable effect of solubility on absorption. Data from four food sources are presented for comparison. Absorbability of food calcium was not clearly related to absorbability of the dominant chemical form in the food concerned. These findings suggest that (1) even under controlled, chemically defined conditions, solubility of a source has very little influence on its absorbability; and (2) absorbability of calcium from food sources is determined mainly by other food components.

Evidence-based criteria in the nutritional context

During the last decade, approaches to evidence-based medicine, with its heavy reliance on the randomized clinical trial (RCT), have been adapted to nutrition science and policy. However, there are distinct differences between the evidence that can be obtained for the testing of drugs using RCTs and those needed for the development of nutrient requirements or dietary guidelines. Although RCTs present one approach toward understanding the efficacy of nutrient interventions, the innate complexities of nutrient actions and interactions cannot always be adequately addressed through any single research design. Because of the limitations inherent in RCTs, particularly of nutrients, it is suggested that nutrient policy decisions will have to be made using the totality of the available evidence. This may mean action at a level of certainty that is different from what would be needed in the evaluation of drug efficacy. Similarly, it is judged that the level of confidence needed in defining nutrient requirements or dietary recommendations to prevent disease can be different from that needed to make recommendations to treat disease. In brief, advancing evidence-based nutrition will depend upon research approaches that include RCTs but go beyond them. Also necessary to this advance is the assessing, in future human studies, of covariates such as biomarkers of exposure and response, and the archiving of samples for future evaluation by emerging technologies.

Dietary calcium: adequacy of a vegetarian diet.

Obtaining sufficient amounts of absorbable dietary calcium to optimize bone density and to protect against bone resorption is a protective measure to lower the risk of osteoporosis. This goal is difficult in Western-style diets without the inclusion of dairy foods, fortified foods, or supplements. Lactovegetarians are able to meet recommended calcium intakes and do not have compromised bone mineral densities. Few other foods provide concentrated sources of absorbable calcium. Estimates of the absorbable calcium content of several plant foods are provided.

Should dairy be recommended as part of a healthy vegetarian diet? Point

A benefit-risk evaluation of the evidence for including dairy foods in the diet is presented. For many persons dairy products provide a substantial portion of essential nutrients, but especially calcium, potassium, and magnesium. Dietary supplements and fortified foods can be alternative sources of these nutrients, although other components of dairy foods such as amino acid composition and conjugated linoleic acid may be instrumental in the benefits associated with dairy product consumption for bone health and reduced risk of stroke, metabolic syndrome, and some cancers. Newer evidence shows that protein-induced calciuria does not have a detrimental effect on net calcium retention, and the concentrations of hormones in milk are not outside of the range of endogenous concentrations. Increased dietary protein, including from milk, can elevate serum concentrations of insulin-like growth factor I, which has an unknown relation to cancer. The concern over consumption of milk leading to increased risk of prostate cancer through reduction of serum 1,25-dihydroxyvitamin D, a potent anti-prostate cancer hormone, has been resolved with new evidence that local production of this hormone is independent of diet. Overall, evidence suggests that being a lactovegetarian has greater health benefits and reduced health risks than being a vegan.