Calcium intakes and femoral and lumbar bone density of elderly U.S. men and women: National Health and Nutrition Examination Survey 2005-2006 analysis.

OBJECTIVES: This analysis was aimed at assessing the benefits of total calcium intake from diet and supplements on both femoral neck and lumbar vertebral bone mineral density (BMD) in a representative sample of older U.S. women and men. DESIGN: For 1384 women and men aged 50-70 and 71+ yr, quintiles of total calcium intake were tested for their association with hip and spine BMD after adjusting for body mass index. All data in this observational study were cross-sectional. DATA SOURCE: Subjects included elderly residents statistically representative of the United States, women and men aged 50 yr and older in the National Health and Nutrition Examination Survey 2005-2006 cohort. MAIN OUTCOME MEASURES: Calcium intakes and femoral and lumbar BMD were evaluated. RESULTS: Total calcium intakes ranged from means of 400+ mg/d in quintile 1 to 2100+ in quintile 5. Little difference in hip or lumbar BMD was found in relation to total calcium consumption in women and men across five quintiles, especially for those aged 50-70, in models adjusted for body mass index only. Femoral hip BMD in men 71 and older increased slightly with high calcium intake (3.6% higher density, P = 0.0391), whereas femoral BMD in women 71 and older decreased slightly with high calcium intake (-3.2%, P = 0.0132). Lumbar BMD remained fairly consistent across all quintiles, but greater variation within each quintile was found compared with the hip. CONCLUSIONS: A usual high calcium intake beyond the recommended dietary allowance of elderly women and men, most commonly achieved by calcium supplements, did not provide any benefit for hip or lumbar BMD. A dietary intake of calcium approaching or meeting the current recommendations was not related to higher BMD of the hip or lumbar spine in late life compared with lower intakes of calcium in older adults.

Micronutrient intakes in two US populations of older adults: lipid research clinics program prevalence study findings.

Dietary intakes of several minerals and vitamins were assessed in two US sub-populations of older men and women between 60 and 80 years as part of the Lipid Research Clinics Program Prevalence Study conducted in the mid-1980s prior to widespread fortification. Dietary intakes were analyzed from 24-hour recalls using the Minnesota Nutrition Coding Center. Descriptive statistics on the two diverse sub-populations were generated for the elderly subjects at the two clinic sites, southern California and Oklahoma. Regression analyses of specific micronutrients were performed while controlling for several variables, namely, age, sex, clinic (region), education, Body Mass Index (BMI), alcohol consumption, and smoking status. Compared to current (1999-2004) Estimated Average Requirements (EARs) and Adequate Intakes (AIs) for three micronutrients without EARs for the US and Canada, several micronutrients were consumed at or close to their EAR values. Exceptions include intakes of vitamin A, vitamin E, folic acid, potassium and calcium which were very low; intakes of thiamin, riboflavin, niacin, and vitamin C were low but closer to the published EAR or AI values. High intakes approaching cut-offs for practically all subjects were found for both groups of elders at the two clinic sites for iron, phosphorus, and sodium. In general, California elderly had somewhat better consumption patterns for the vitamins, but the Oklahomans, males at least, had higher overall mineral intakes. The micronutrient deficits found in this small study suggest that most elderly US citizens were likely to be deficient in five micronutrients and marginally insufficient in four others in the mid-1980s and, despite even greater fortification currently, elderly intakes seem not to have improved substantially since the 1980s, except for subjects who are regular multi-supplement users.

Macronutrient intakes of elderly in the Lipid Research Clinics Program Prevalence Study.

As part of the Lipid Research Clinics (LRC) Program Prevalence Study of coronary heart disease risk factors, nutrient intakes of two US populations over 59 years of age were determined by 24-hour recalls in the 1970s. Characteristics of the populations were (1) California: suburban, upper-middle class, 95% high school graduates, 10% blue collar occupations; (2) Oklahoma: rural lower-middle class, 75% high school graduates, and 40% blue-collar occupations. Macronutrients consumed by both populations were similar, except for alcohol. For both men and women, energy intake was approximately 25 kcal/kg/day (body weight) sources of energy were approximately 40% from carbohydrate, 16% from protein, 37% from fat, and 4% from alcohol. The Oklahoma population, however, consumed significantly less alcohol than did Californians. Percentages of calories from fatty acids were approximately 14% from saturated and 6% from polyunsaturated, which yielded a polyunsaturated: saturated ratio of 0.48. The intake of cholesterol for women was 190 mg/1000 kcal and for men, 210 mg/1000 kcal. Between the ages of 60 and 69, the Oklahoma men consumed more energy than did the California men. Both sexes demonstrated lower energy intakes with advancing age and with increasing body mass index. The higher energy intake of the Oklahoma cohort aged 60-69 was attributed to the greater physical demands of their occupations, but this difference disappeared after age 70. The California and Oklahoma women had similar caloric intakes beyond age 60. In summary, the LRC findings suggest that geographically diverse American populations consumed in the late 1970s remarkably similar intakes of macronutients and cholesterol, with the only major exception being energy from alcoholic beverages.

Isoflavones and skeletal health: are these molecules ready for clinical application?

A review of the recent literature on the effects of isoflavones was undertaken to determine whether molecules such as genistein and daidzein, aglycone derivatives of soybeans, might have benefit in the prevention and treatment of osteoporosis. The current standard for science-based medicine is the documentation of efficacy of an agent under controlled, randomized, prospective conditions. A few short clinical investigations have been undertaken using isoflavones (along with soy protein), but they had limitations in study design, and the numbers of women studied were small. Other evidence from animal models, in vitro experiments, and epidemiological reports suggest that the isoflavones have skeletal benefits in women with little or no ovarian estrogen production. A clear need exists for prospective human trials, using the required conditions of randomized clinical trials and designs, to satisfy objectively the needs for science-based medicine and for appropriate clinical applications.

Isoflavones regulate interleukin-6 and osteoprotegerin synthesis during osteoblast cell differentiation via an estrogen-receptor-dependent pathway.

The hypothesis tested in this in vitro study was that the expression and production of dietary isoflavone-mediated osteoclastogenesis-regulatory cytokines, such as interleukin-6 (IL-6) and osteoprotegerin (OPG), are related to the different levels of estrogen receptors expressed in two hFOB osteoblastic cell lines. OPG mRNA expression was significantly increased in both hFOB1.19 and hFOB/ER9 cells treated with 17 beta-estradiol, genistein, or daidzein at 10(-8)M in comparison to vehicle (control) (P<0.05). In both cell lines, the release of IL-6 was suppressed, while OPG production was enhanced by isoflavone treatments (P<0.05). The increased expression of OPG and decreased IL-6 production by isoflavones were dose-dependent. Responses to isoflavones were much stronger in hFOB/ER9 cells, which express the estrogen receptor 20 times higher than those in hFOB1.19 cells. After adding the ER binding blocker, ICI-182,780, the effects of isoflavones on OPG and IL-6 production disappeared. In summary, the inhibition by dietary isoflavones of IL-6 production and the stimulation of OPG appear to be mediated, at least in part, via a genomic pathway operating through estrogen receptors and gene expression mechanisms.

Isoflavones and bone: animal and human evidence of efficacy.

Previous reports of soy extracts and isoflavone-enriched preparations studied in animals and humans have found that these molecules, when given at appropriate doses, have positive effects on the skeleton, including improvements in bone mineral content (BMC) and bone mineral density (BMD). A reduction in fracture risk of human subjects has not yet been shown in a prospective trial. Isoflavones, which exist in significant amounts only in soybeans, exert estrogen-like effects in human bone cells because of their unique organic structures that are similar to that of estradiol. The discovery of the b isoform of the estrogen receptor (ER) suggests that the molecular regulation of bone remodeling by estrogens, or estrogen-like molecules, including isoflavones, is more complex than previously thought. Depending on the type of ER present in a particular tissue, isoflavones may act as weak estrogen agonists or as weak estrogen antagonists. For example, isoflavones act as weak estrogen agonists in osteoblasts, but in reproductive cells, such as in the breast and uterus, they behave as weak estrogen antagonists. Weak agonistic effects of the isoflavones include stimulation of osteoblast proliferation and differentiation and increasing the production of cytokines that may inhibit osteclastic activity. The selective beneficial effects of estrogen-like molecules in bone tissues, compared to the anti-estrogenic effects in cells of reproductive tissues, make isoflavones attractive for the promotion of bone health. Relatively greater values of BMC and BMD of Asian populations with high consumption of soy isoflavones throughout life, compared to those with lower intakes, indirectly support the skeletal benefits of this pattern of intake of these estrogen-like molecules.