Factors associated with calcium absorption efficiency in pre- and perimenopausal women.

BACKGROUND: The amount of calcium ingested by an individual may affect several chronic conditions, including osteoporosis, hypertension, and colon cancer. However, individuals vary in their ability to absorb the calcium they consume. OBJECTIVE: The purpose of this study was to examine sources of interindividual variation in the efficiency of calcium absorption in women. DESIGN: Fractional calcium absorption was estimated in 142 healthy pre- and perimenopausal women. Dietary habits, lifestyle factors, calciotropic hormones, and vitamin D receptor gene polymorphisms were also assessed. RESULTS: Calcium absorption values averaged 35% and ranged from 17% to 58%. Fractional calcium absorption was positively associated with body mass index (r = 0.22, P = 0.007), dietary fat intake (r = 0.29, P = 0.001), serum 1,25 dihydroxyvitamin D [1,25(OH)(2)D] concentrations (r = 0.23, P = 0. 006), and parathyroid hormone concentrations (r = 0.21, P = 0.015). Fractional calcium absorption was inversely associated with total calcium intake (r = -0.18, P = 0.030), dietary fiber intake (r = -0. 19, P = 0.028), alcohol consumption (r = -0.14, P = 0.094), physical activity (r = -0.22, P = 0.007), and symptoms of constipation (r = -0.16, P = 0.059). In stepwise regression analysis, dietary fat, dietary fiber, serum 1,25(OH)(2)D, and alcohol consumption emerged as independent predictors of calcium absorption, explaining 21.02% of the observed variation. Women in the lowest tertile of the ratio of dietary fat to fiber had 19% lower fractional calcium absorption values than did women in the highest tertile of ratio of dietary fat to fiber (test of trend, P < 0.001). CONCLUSIONS: There is a wide range of calcium absorption values in healthy women. The amount of dietary fat consumed relative to dietary fiber appears to have an important role in determining differences in calcium absorption performance among individuals.

Correlates of quantitative ultrasound in the Women's Healthy Lifestyle Project.

Quantitative ultrasound (QUS) assessment of bone is a strong predictor of hip fractures and is currently an FDA-approved tool to identify women at risk of osteoporosis. However, few studies have investigated the lifestyle and genetic correlates of QUS in women. This study investigated the cross-sectional associates of several lifestyle, demographic and genetic factors with calcaneal QUS parameters (broadband ultrasound attenuation (BUA) and speed of sound (SOS)) in 393 women aged 45-53 years. Leisure-time and historical physical activity, dietary calcium and protein, body composition, vitamin D receptor genotypes, menopause status, other health behaviors, calcaneal QUS parameters and bone mineral density (BMD) were assessed at a single clinic visit. Lean mass, recent physical activity and African-American race were the strongest correlates of SOS whereas dietary protein, calcium and recent physical activity were the strongest correlates of BUA. These predictors explained 13% and 6% of the variance in SOS and BUA, respectively. Smoking, alcohol intake, education, hormone replacement therapy, calcium and vitamin D supplements, historical physical activity and vitamin D receptor genotypes were not significantly associated with BUA or SOS. Lean body mass and premenopausal status were the strongest correlates of lumbar BMD whereas lean body mass, physical activity, African-American race and body mass index were significantly related to femoral neck BMD. Physical activity remained predictive of SOS after controlling for lumbar BMD. The spectrum and magnitude of risk factors for SOS and BUA, including lean body mass, physical activity, race, protein and calcium intake, parallel previously observed predictors of BMD.

mtDNA variation indicates Mongolia may have been the source for the founding population for the New World.

mtDNA RFLP variation was analyzed in 42 Mongolians from Ulan Bator. All four founding lineage types (A [4.76%], B [2.38%], C [11.9%], and D [19.04%]) identified by Torroni and colleagues were detected. Seven of the nine founding lineage types proposed by Bailliet and colleagues and Merriwether and Ferrell were detected (A2 [4.76%], B [2.38%], C1 [11.9%], D1 [7.14%], D2 [11.9%], X6 [16.7%], and X7 [9.5%]). Sixty-four percent of these 42 individuals had "Amerindian founding lineage" haplotypes. A survey of 24 restriction sites yielded 16 polymorphic sites and 21 different haplotypes. The presence of all four of the founding lineages identified by the Torroni group (and seven of Merriwether and Ferrell's nine founding lineages), combined with Mongolia's location with respect to the Bering Strait, indicates that Mongolia is a potential location for the origin of the founders of the New World. Since lineage B, which is widely distributed in the New World, is absent in Siberia, we conclude that Mongolia or a geographic location common to both contemporary Mongolians and American aboriginals is the more likely origin of the founders of the New World.

mtDNA variation in the Yanomami: evidence for additional New World founding lineages.

Native Americans have been classified into four founding haplogroups with as many as seven founding lineages based on mtDNA RFLPs and DNA sequence data. mtDNA analysis was completed for 83 Yanomami from eight villages in the Surucucu and Catrimani Plateau regions of Roraima in northwestern Brazil. Samples were typed for 15 polymorphic mtDNA sites (14 RFLP sites and 1 deletion site), and a subset was sequenced for both hypervariable regions of the mitochondrial D-loop. Substantial mitochondrial diversity was detected among the Yanomami, five of seven accepted founding haplotypes and three others were observed. Of the 83 samples, 4 (4.8%) were lineage B1, 1 (1.2%) was lineage B2, 31 (37.4%) were lineage C1, 29 (34.9%) were lineage C2, 2 (2.4%) were lineage D1, 6 (7.2%) were lineage D2, 7 (8.4%) were a haplotype we designated "X6," and 3 (3.6%) were a haplotype we designated "X7." Sequence analysis found 43 haplotypes in 50 samples. B2, X6, and X7 are previously unrecognized mitochondrial founding lineage types of Native Americans. The widespread distribution of these haplotypes in the New World and Asia provides support for declaring these lineages to be New World founding types.

Nigerian geophagical clay: a traditional antidiarrheal pharmaceutical.

The chief geophagical clay entering the West African market system comes from the village of Uzalla, Nigeria. Village inhabitants ascribe antidiarrheal properties to the clay, and they use it in traditional medicinal preparations to counteract intestinal problems. Mineralogical analyses demonstrate a striking similarity between the Uzalla village clay and the clay in the commercial pharmaceutical Kaopectate.