Calcium requirements of physically active people

From waste of marine culture to natural patch in cardiac tissue engineering

Sea squirt, as a highly invasive species and main biofouling source in marine aquaculture, has seriously threatened the biodiversity and aquaculture economy. On the other hand, a conductive biomaterial with excellent biocompatibility, and appropriate mechanical property from renewable resources is urgently required for tissue engineering patches. To meet these targets, we presented a novel and robust strategy for sustainable development aiming at the marine pollution via recycling and upgrading the waste biomass-sea squirts and serving as a renewable resource for functional bio-scaffold patch in tissue engineering. We firstly demonstrated that the tunic cellulose derived natural self-conductive scaffolds successfully served as functional cardiac patches, which significantly promote the maturation and spontaneous contraction of cardiomyocytes both in vitro and enhance cardiac function of MI rats in vivo. We believe this novel, feasible and “Trash to Treasure” strategy to gain cardiac patches via recycling the waste biomass must be promising and beneficial for marine environmental bio-pollution issue and sustainable development considering the large-scale consumption potential for tissue engineering and other applications.

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Fouling sea squirts used as scaffold materials can effectively solve the pollution problem of marine aquaculture.

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The natural electrical conductivity of the sea squirts derived scaffold is similar to that of natural myocardial tissue.

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Cellulose scaffold from sea squirts has a good orientation, and its structure is similar to natural myocardial tissue.

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Sea squirts cellulose derived natural self-conductive scaffolds were successfully served as the functional cardiac patches.

A New Calcium Oral Controlled-Release System Based on Zeolite for Prevention of Osteoporosis

Osteoporosis, a systemic skeleton disease, can be prevented by increasing calcium levels in serum via administration of calcium salts. However, traditional calcium-based formulations have not appeared to be effective, hence the purpose of the present work has been to prepare and test in vitro/vivo a formulation able to gradually release calcium during transit over the GI tract, thus increasing bioavailability and reducing daily dose, and hence, side effects. Calcium controlled-release granules based on zeolite and Precirol^® were prepared. In the best case, represented by granules sized 1.2 mm, containing 20% Precirol^®, 19% zeolite, 60% calcium (granule), the release lasted ≈6 h. The release is controlled by diffusion of calcium ions through the aqueous channels forming within granules, once these come into contact with physiological fluids. Such a diffusion is hindered by the interaction of calcium ions with the negatively charged surface of the zeolite. Ovariectomy was used to make rats osteopenic. For in vivo studies, rats were divided into the following groups. Sham: not treated; ova: ovariectomized (ova); CaCl₂ 1.0 g: ova, treated with 1.0 g/die Ca²⁺; CaCl₂ 0.5 g: ova, treated with 0.5 g/die Ca²⁺; granule 1.0 g, or granule 0.5 g: ova, treated with granules equivalent to 1.0 g/die or 0.5 g/die Ca²⁺ in humans. Ca²⁺ amounts in femur bone and bone marrow, femur mechanical characteristics, and femur medullary canalicule diameter were measured and the same efficacy rank order was obtained: ova < CaCl₂ 0.5 g < CaCl₂ 1.0 g < granule 0.5 g ≈ granule 1.0 g ≈ sham. The results show promise of an effective prevention of osteoporosis, based on a controlled-rate administration of a calcium dose half that administered by the current therapy, with reduced side effects.

Canadians' Dietary Intake from 2007 to 2011 and across Different Sociodemographic/Lifestyle Factors Using the Canadian Health Measures Survey Cycles 1 and 2

BACKGROUND

Nutrition is an important factor that impacts health, yet in Canada, there have been only a few surveys reflecting dietary intakes. The Canadian Health Measures Survey (CHMS) is a national survey that includes both food intake data as targeted questions and objective health measures. The aim of this research was to determine how food group intake data reported in CHMS is related to food group intakes from Canadian Community Health Survey (CCHS) (2004). A secondary objective was to examine the dietary status of Canadians across sociodemographic levels.

METHODS

The CHMS Cycles 1 and 2 food group intake data (meat and alternatives; milk products; grains; vegetables and fruits; dietary fat consumption; and beverages) of Canadians (6-79 years, n=11,387) were descriptively compared to previously reported intake of Canadians from CCHS 2.2 in 2004. Further, Canadians' food intakes were assessed across sociodemographic characteristics.

RESULTS

The CHMS dietary intake data from vegetables and fruits and from milk products groups were similar to the dietary intake reported from CCHS 2.2. For the other food groups, the difference in intakes suggested CHMS data by FFQ were not complete. However, similar patterns in food intakes with regards to age/sex and income were observed in both surveys.

CONCLUSION

Not all food groups measured in CHMS provide complete dietary intake data as compared to CCHS 2.2, yet CHMS food group intakes provide valuable information when it comes to evaluating dietary intake across different population groups.

Rapid Weight Loss and Dietary Inadequacies among Martial Arts Practitioners from Poland

Healthy nutrition and maintaining a normal body weight are very important for reducing the risk of various diseases not only among the general population, but also among athletes, especially combat sport athletes. The aim of the study was to evaluate the prevalence of rapid weight loss (RWL) and to indicate eventual dietary inadequacies among professional martial arts practitioners. Sixty-two male athletes (aged: 23 ± 4) completed a questionnaire (i.e., frequency of food group consumption, questions about training and RWL) and single 24-h dietary recall. This study confirmed the high prevalence of RWL in athletes (58%) for two to three days before the competition, which allowed for reduction of 3.4 ± 1.0 kg (4.3 ± 1.5%) of their body weight. Many dietary inaccuracies were found such as: lower than recommended by nutrition experts, level of consumption of dairy products, grain products, fruit, and vegetables, and insufficient intake of energy, carbohydrates, minerals (especially iodine, potassium, calcium) and vitamins (especially D, folate, C, E) during the training day. Adequate nutrition is a natural support for the whole training process, and may allow for regulation of body weight in a longer period and in a safer manner; thus, there is a need for nutrition education dedicated to athletes and their trainers.

Effect of Calcium Derived from Lithothamnion sp. on Markers of Calcium Metabolism in Premenopausal Women

A double-blind crossover pilot trial tested the hypothesis that botanically derived calcium could demonstrate greater influence over calcium metabolism markers compared with a nonplant-derived calcium carbonate supplement or placebo. Twelve fasting female subjects received a single oral dose of Aquamin F™ (derived from the marine algal Lithothamnion sp.), or calcium carbonate, or placebo. Blood and urine samples were collected at baseline and over 12 h to evaluate ionized and total calcium and parathyroid hormone (PTH). Subjects treated with Aquamin F demonstrated significantly greater urinary clearance of calcium after 12 h compared with placebo (P = .004). Following a meal at 90 min, subjects treated with Aquamin F demonstrated a more prolonged suppression of serum PTH concentration (significantly lower than placebo at 90, 120, and 240 min). Calcium carbonate provided an intermediate response; urinary clearance was not significantly different from placebo treatment and PTH was only significantly lower than placebo at 90 min. Aquamin F may demonstrate greater influence over these markers of calcium metabolism than calcium carbonate or placebo, as suggested by a greater calciuric response and a more prolonged suppression of serum PTH concentrations following a meal in premenopausal women.

Low-calcium diet prevents fructose-induced hyperinsulinemia and ameliorates the response to glucose load in rats

Background

Consuming a fructose-rich diet leads to hyperinsulinemia, impaired glucose tolerance, and insulin resistance. In humans, the consumption of high levels of refined sugars often coincides with a diet containing suboptimal levels of calcium. Calcium and carbohydrate metabolism interact, so there is potential for fructose to have different health outcomes depending on whether the diet is calcium-rich or calcium-poor.

Methods

We evaluated the metabolic effects of feeding fructose to rats that were maintained on either a calcium-replete diet or a low-calcium diet. Growing male Sprague Dawley rats were fed diets based on the AIN-93G formulation, with the main source of carbohydrate derived either from a mixture of cornstarch and sucrose or from fructose. Half the rats given each carbohydrate source were fed calcium at recommended levels (125 mmol/kg Ca²⁺); the others were fed a diet low in calcium (25 mmol/kg Ca²⁺). At various times, glucose and insulin tolerance tests were conducted to assess glucose metabolism.

Results

Rats fed low-calcium diet had lower fasting insulin levels irrespective of the carbohydrate source they ate. They had a normal glycemic response to a glucose load and did not develop hyperinsulinemia under conditions of fructose feeding. The drop in blood glucose levels in response to insulin injection was larger in rats fed low-calcium diet than in those fed calcium-replete diet.

Conclusions

Low-calcium diet prevented fructose-induced hyperinsulinemia and improved glucose handling under conditions of fructose feeding. Potential mechanisms underlying these effects of the low-calcium diet remain to be determined, but possibilities include impairment of insulin release from the pancreas and improved peripheral insulin sensitivity.

Alternative therapies for the prevention and treatment of osteoporosis

Osteoporosis is a medical condition that affects millions of men and women. People with this condition have low bone mass, which places them at increased risk for bone fracture after minor trauma. The surgeries and treatments required to repair and heal bone fractures involve long recovery periods and can be expensive. Because osteoporosis occurs frequently in the elderly, the financial burden it places on society is likely to be large. In the United States, the Food and Drug Administration has approved several drugs for use in the prevention and treatment of osteoporosis. However, all of the currently available agents have severe side effects that limit their efficacy and underscore the urgent need for new treatment options. One promising approach is the development of alternative (nonpharmaceutical) strategies for bone maintenance, as well as for the prevention and treatment of osteoporosis. This review examines the currently available nonpharmaceutical alternatives that have been evaluated in in vitro and in vivo studies. Certain plants from the following families have shown the greatest benefits on bone: Alliceae, Asteraceae, Thecaceae, Fabaceae, Oleaceae, Rosaceae, Ranunculaceae, Vitaceae, Zingiberaceae. The present review discusses the most promising findings from studies of these plant families.

Confusion on the complexity of calcium balance

Calcium balance is an overall assessment of the net calcium taken in minus the net calcium taken out. It can only be assessed when patients are in steady state and requires complicated isotope methods that can simultaneously assess intestinal absorption and endogenous secretion, urinary and stool excretion, bone calcium uptake and removal, and dialysate calcium removal. By virtue of the need for steady state, formal balance studies cannot be accurately carried out in patients on dialysis. However, many of the components of calcium balance have been assessed. Importantly, because 99% of calcium is in bone, studies must accurately assess both the rapidly exchangeable calcium from the bone surface and the net bone calcium balance that results from the difference in bone formation minus resorption. While it is tempting to adjust the dialysate calcium concentration to correct the net positive calcium balance that is likely present in patients who receive calcium-based phosphate binders, the reality is that the highly variable, yet important, role of bone cannot be easily assessed at the bedside. Thus, it is best to prevent the calcium overload in the first place by avoiding high-dose calcium-based phosphate binders and optimizing bone remodeling.

The effect of polyunsaturated fatty acids on bone health

The essential polyunsaturated fatty acids (PUFAs) are divided into two classes, n-3 (ω-3) and n-6 (ω-6) and their dietary precursors are α-linolenic (ALA) and linoleic acid (LA), respectively. PUFAs are precursors of a wide range of metabolites, for example eicosanoids like prostaglandins and leukotrienes, which play critical roles in the regulation of a variety of biological processes, including bone metabolism.

A large body of evidence supports an effect of PUFA on bone metabolism which may be mediated by regulation of osteoblastogenesis and osteoclast activity, change of membrane function, decrease in inflammatory cytokines, such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumour necrosis factor alpha (TNF-α), modulation of peroxisome proliferators-activated receptor γ (PPARγ) and influence in NO secretion and NO synthase.

Animal studies have shown that a higher dietary omega-3/omega-6 fatty acids ratio is associated with beneficial effects on bone health. Human studies conducted in elderly subjects suggest that omega-3 instead of omega-6 has a positive effect on bone metabolism. In spite of increasing evidence, studies conducted in humans do not allow us to draw a definitive conclusion on the usefulness of PUFAs in clinical practice.

High-Calcium Milk Prevents Overweight and Obesity among Postmenopausal Women

Background

The Sixth National Nutrition Survey 2003 revealed that the highest prevalence of overweight and obesity among Filipino female adults (30.8%) was found in the age group from 40 to 59 years. Obesity is associated with a number of chronic diseases, including cardiovascular disease, hypertension, and diabetes. Low calcium intake has been identified as a potential contributing factor to overweight and obesity.

Objective

To assess the effect of a high-calcium, fortified, low-fat milk drink with added vitamin D versus a low-calcium placebo drink on anthropometric measurements of postmenopausal women.

Methods

Women who were at least 5 years postmenopausal were invited to participate in the study. Potential participants underwent three stages of screening: initial interview, dual-energy x-ray absorptiometry, and blood testing for biochemical screening. Anthropometric indices were measured at baseline and the end of the study. Sixty women were qualified to participate in the study. The women were randomly assigned to two groups, one of which received 400 ml of the high-calcium milk daily for 16 weeks while the other received the placebo drink.

Results

No significant increases were observed in the anthropometric indices of the subjects receiving the high-calcium fortified milk at the end of the study. However, there were significant increases in the weight ( p = .008), body mass index ( p = .007), and waist ( p = .018) and hip ( p = .003) circumferences of the subjects receiving the placebo drink.

Conclusions

A change in dietary calcium intake may be a useful measure as part of an overall approach to prevent the occurrence of overweight and obesity among postmenopausal women.

Calcium supplementation and 4-week exercise on blood parameters of athletes at rest and exhaustion

In the present study, experiments were designed to investigate if supplementation with calcium during 4 weeks had an effect on blood parameters in sedentary male athletes at rest and exhaustion. Thirty healthy subjects of ages ranging from 18 to 22 years were included in the study. The subjects were separated into three groups, as follows: Group 1 consisted sedentary athletes receiving 35 mg/kg/day calcium gluconate. Group 2 included subjects equally supplemented with calcium training 90 min/day for 5 days/week. Group 3 were subject to the same exercise regime but did not receive calcium supplements. Blood parameters were determined in the experimental subjects at rest and after exhaustion. The leukocyte count (WBC) of athletes in groups 2 and 3 were significantly higher at exhaustion (p < 0.05). There were no significant differences in the WBC of the two supplemented groups. The erythrocyte count (RBC) was increased in the supplemented athletes after training (p < 0.05), but hemoglobin, hematocrit, and thrombocyte levels remained unchanged. The mean corpuscular volume increased in the calcium-supplemented group at rest (p < 0.05). These results suggest that calcium supplementation only causes increases in white and red blood cell counts in athletes after exhaustion while other hematological parameters remain unchanged.

Diet, body composition, and bone mass in well-trained cyclists

Cycling is believed to be associated with low bone mass. In this study, we investigate food intake, body composition, and bone mass in well-trained young adult cyclists compared with those in sedentary controls. Four-day estimated diet records were used to study dietary intake in 31 cyclists and 28 sedentary controls (all male, 24yr old on average), together with maximal oxygen uptake (VO(2max)), body composition, and bone mass measurements (dual-energy X-ray absorptiometry). The VO(2max) values were twice as high as those in the cyclists, whereas no significant difference in bone mass was observed between cyclists and controls. A total of 10 cyclists and 9 controls had low bone mass. Total-body lean mass and appendicular skeletal muscle mass were higher in cyclists (p<0.001), whereas percentage of body fat was lower (p<0.001) compared with that of the controls. Energy and macro- and micronutrient intake was higher in the cyclists than in the controls (p<0.01). Energy consumption was considered adequate in the cyclists, whereas lipid and protein intake was higher than the American College of Sports Medicine recommendation. Lipid consumption negatively correlated with bone mass in the athletes. Our results demonstrate that cycling was associated with greater aerobic conditioning and lean mass without significant association with bone mass compared with sedentary controls.

Independent and combined effect of nutrition and exercise on bone mass development

Food intake provides the necessary components for adequate metabolic functions in bone. Calcium, phosphorus, vitamin D, magnesium, proteins, and fluoride are some of the most important nutrients in this regard. These have different effects on bone mass. Additionally, exercise has been shown to elicit osteogenic responses in bone development; indeed, it seems to potentiate, for example, the effect of calcium supplementation on bone mass. However, the nutrition-exercise-bone mass relationship is complex and needs further in-depth investigation. As a first step, therefore, we reviewed current knowledge about the role of nutrition on the development of bone tissue and how physical activity affects the nutrient-bone relationship.

Nutritional profile of the Brazilian Amputee Soccer Team during the precompetition period for the world championship

OBJECTIVE

The purpose of this study was to determine the dietary and anthropometric profiles of the Brazilian amputee soccer players during the training period before the world soccer amputee championship, according to their positional roles in the game.

METHODS

Fifteen male athletes participated in the study. Data on height, weight, skinfold thickness, and circumferences were collected to assess nutritional status. Dietary intake was obtained by using 6-d dietary records, analyzed by a Nutrition Support Program for total energy intake, carbohydrates, proteins, lipids, vitamins, and minerals. One-way analysis of variance was used to identify differences in groups (P < 0.05).

RESULTS

Midfield players were heavier than the others, and this difference may have been caused by a large quantity of subcutaneous fat. Dietary data showed a low carbohydrate intake and high protein and fat intakes. No athlete met the recommendations for vitamin E, and forward players did not meet recommendations for calcium.

CONCLUSION

Amputee athletes need an individualized nutritional orientation and the lack of information about disabled sports and athletes highlights the need for more studies in this area.

Iron restriction negatively affects bone in female rats and mineralization of hFOB osteoblast cells

We previously reported that severe iron deficiency negatively affects bone microarchitecture. Here we determined whether marginal iron restriction that reflects some human consumption patterns could have similar consequences. Thirty-two weanling female rats were randomly divided into four groups and fed the following diets for 10 weeks: (i) iron-adequate, calcium-adequate (FeA:CaA), (ii) calcium-restricted (FeA:CaR), (iii) iron-restricted (FeR:CaA), and (iv) both calcium- and iron-restricted (FeR:CaR) diets. DEXA analysis revealed that CaR decreased bone mineral density (BMD), and FeR decreased whole-body bone mineral content (BMC). Iron-restricted and calcium-restricted groups had lower BMD than did their adequate counterparts. All treatment-restricted groups had lower BMD in the fourth lumbar (L-4) vertebrae than the FeA:CaA group. Vertebrae BMD was lower in all treatment groups compared to the control group, and for BMC, the CaR groups were lower than the CaA groups and the FeR groups were lower that the FeA groups, and BMC were lower in iron- and calcium-restricted groups. The microarchitecture of the L-4 vertebrae was compromised in FeA:CaR, FeR:CaA, and FeR:CaR: (i) the connectivity density was reduced by FeR and by CaR; and (ii) trabecular number was decreased and trabecular separation was increased by FeR. Cortical thickness of the femur was reduced by both FeR and CaR. Finite element analysis revealed that L-4 vertebrae from the FeR:CaA group had greater internal stress with an applied force than the FeA:CaA group and, thus, would be more likely to break. Chelation of iron in cultured osteoblast cells impaired mineralization but had no impact upon Type I collagen deposition. Iron depletion, similar to that occurring among some human populations, reduced bone strength and microarchitecture based on the in vivo and in vitro results reported here. Impaired mineralization with iron depletion appears to be a possible mechanism for the observed bone abnormalities.

Optimizing bone health and calcium intakes of infants, children, and adolescents

Most older children and adolescents in the United States currently do not achieve the recommended intake of calcium. Maintaining adequate calcium intake during childhood and adolescence is necessary for the development of peak bone mass, which may be important in reducing the risk of fractures and osteoporosis later in life. Optimal calcium intake is especially relevant during adolescence, when most bone mineral accretion occurs. Because of the influence of the family's diet on the diet of children and adolescents, adequate calcium intake by all members of the family is important. Assessment of calcium intake can be performed in the physician's office. A well-rounded diet including low-fat dairy products, fruits, and vegetables and appropriate physical activity are important for achieving good bone health. Establishing these practices in childhood is important so that they will be followed throughout the life span.

Newer Perspectives on Calcium Nutrition and Bone Quality

It is now generally accepted that an adequate calcium intake is important for building and maintaining a skeleton that expresses quantitatively the full genetic program and reduces lifetime fracture risk. In this brief review we focus mainly on a new and growing body of evidence indicating a benefit of adequate calcium intake on qualitative features of the skeleton that, independent of the quantity of bone, themselves influence skeletal strength and fragility. Change in bone mass and size during growth are dependent on both calcium intake and exercise, with the largest differences being observed in prepubertal children who have both high exercise levels and high calcium intakes. Much of this benefit is expressed as increased bone diameter (and hence stiffness). Fracture risk peaks at about the time of puberty and is inversely related to bone mass. However, even prepubertally, children with low calcium intakes have been reported to have a fracture rate 2.7x that of their birth cohort. Bone remodeling triples from age 50 to 65 in typical women and is now recognized to have primarily a homeostatic basis. While remodeling improves bone strength by repairing acquired defects, homeostatic remodeling, while necessary to maintain blood calcium levels, contributes only structural weakness to bone. High calcium intakes in postmenopausal and older women reduce this homeostatic remodeling to approximately pre-menopausal values and improve bone strength immediately, well prior to any appreciable change in bone mass.

A pilot intervention to increase calcium intake in female collegiate athletes

Calcium intake in adolescent and young adult female athletes often is inadequate to optimize peak bone mass, an important determinant of osteoporosis risk. The purpose of this study was to determine if calcium supplementation in eumenorrheic female collegiate athletes increases intake to recommended levels and promotes increases in bone mineral density (BMD). Forty-eight eumenorrheic female athletes from several college teams (15 soccer, 7 cross-country, 8 indoor track, and 18 basketball) were randomized at the beginning of a competitive season to receive either an oral calcium supplement (1000 mg calcium citrate/400 I.U. Vitamin D) or placebo daily throughout the training season (16 weeks). Self-reported daily pill intake was obtained every 2 weeks to assess adherence. Calcium intake was evaluated using the Rapid Assessment Method, and total body and leg BMD was measured at pre-, mid-, and postseason using dual energy x-ray absorptiometry (DEXA; Hologic QDR-2000). Pre-season calcium intake was lower than national recommendations for this age group (12), averaging 842 mg/d (SD = 719) and was lower in the placebo group compared to the supplemented group (649 +/- 268 vs. 1071 +/- 986 mg/d, respectively; p = .064). Adherence to supplementation was good, averaging 70% across the training season. Supplementation boosted total calcium intake to a mean of 1397 +/- 411 mg/d, which is consistent with recommended levels for this group (37). Supplementation did not influence BMD change during this 16-week intervention. Across teams, a small increase of 0.8% was observed in leg BMD. Change in total body BMD was modified by team, with a significant increase of 1.5% observed in basketball players. These results indicate that providing calcium supplements of 1000 mg/d is adequate to boost total intake to recommended levels during athletic training. Longer intervention trials are required to determine whether calcium supplementation has a positive effect on BMD.

Peak bone mineral area density and determinants among females aged 9 to 24 years in Mexico

INTRODUCTION

Peak bone mineral area density is the amount of bone tissue present when skeletal maturation is completed. The exact age at which bone accumulation reaches a plateau varies with skeletal region. In Mexico and other Latin American countries, there are very few reports on bone mineral area density at early age.

MATERIAL AND METHODS

A cross-sectional study of 461 females between 9 and 24 years of age in Cuernavaca, Mexico, distributed proportionately by age group, determined the bone mineral density (BMD) in femur, lumbar spine, and subcranial skeleton, using a Hologic 4500-Series A osteodensitometer. The peak bone mineral area density (PBM) was determined by using the sigmoid growth model defined by Raymond-Pearl (CSRP). Cohort comparisons among different age groups were developed to evaluate BMD in three skeletal regions, with the Dunnett test, comparing the slopes of BMD by each age stratum. Also, the primary determinants of BMD were evaluated through models of multiple linear regression.

RESULTS

The timing of PBM is highly site specific with some skeletal regions reaching PBM earlier: beginning with the femur, and later reaching the lumbar spine and subcranial skeleton. Using a multivariate model, age and body weight were important predictors of BMD in the three anatomical regions studied ( p<.001). The percentage of fat is associated in an inversely proportionate manner ( p<.005), as independent predictors for BMD in the lumbar spine. The age of the onset of menstruation is also a predictor of BMD in the lumbar spine ( p<0.05); vigorous activity is an important predictor in the subcranial skeleton ( p<0.001).

DISCUSSION

For Mexican females in the state of Morelos, the BMD are similar to that reported in a number of ethnic groups. In mestizo females the timing of PBM is highly site specific with some skeletal regions acquiring PBM earlier: specifically, in the femoral region where PBM rapidly reached a plateau. In Mexico, early strategies for preventing osteoporosis should be focused on promoting physical activity and appropriate eating habits (control of obesity, among others) during the puberty stage.

Protective role of n-3 lipids and soy protein in osteoporosis

It is well established that bone loss due to estrogen deficiency after menopause is greater in women consuming higher quantities of animal protein than in women consuming vegetable protein, particularly soy protein. Besides the dietary protein source altering bone loss, it has also been postulated recently that the source of a higher n-6/n-3 ratio in dietary oils is implicated in causing osteoporosis. Both animal and human studies have indicated that an increased intake of n-6 fatty acids from vegetable oils elevates prostaglandin E(2) levels as well as pro-inflammatory cytokines such as IL-1, IL-6 and TNF-alpha. Interestingly, it has been found that lack of estrogen also increases the production of these cytokines by immune cells and thereby activates osteoclasts during the peri-menopausal period. We speculated that the use of n-3 fatty acids and soy protein, which are known to act as anti-inflammatory and down regulate pro-inflammatory cytokines, may also protect against bone loss by decreasing osteoclast activation and bone resorption. Similar to the results of others, our ongoing studies indeed show that the bone loss in ovariectomized mice is significantly attenuated by feeding diets enriched with either fish oil or soy protein when compared to corn oil and casein-fed mice. One of the mechanisms appears to be decreasing the activation of receptor activator of NF-kappaB ligand (RANKL) on T cells, which has been found to increase osteoclast activation along with increasing pro-inflammatory cytokines in OVX mice. Since hormone replacement therapy has been found to cause adverse effects, further both animal and human studies are required with moderate soy protein and fish oil supplements in understanding the mechanisms involved in altering immune function and bone loss during menopause in women and aging in men.

Interaction of science, consumer practices and policy: calcium and bone health as a case study

Data to support a relationship between calcium and bone health are a major part of the body of evidence that underlie calcium-related policy in the United States. Examples of these policies include dietary intake recommendations, health claims for calcium and osteoporosis on food labels and an objective to improve calcium intake of the U.S. population in Healthy People 2010. Median calcium intakes among females fall below recommended levels after childhood even when supplemental calcium intakes are included. This is a concern in light of data that support a positive relationship between calcium and bone health. Most of the studies on the calcium-bone relationship have focused on older women, and several have used fracture as the endpoint; a meta-analysis of their results suggests that increased calcium intake is associated with approximately 30% decrease in fracture risk. Studies in children, adolescents and premenopausal women have focused on the relationship between calcium and bone mineral density rather than fracture; most of these also support a positive relationship between calcium intake and skeletal health although some data gaps remain. Calcium appears to be a threshold nutrient (e.g., intakes above a certain level do not result in further benefit to bone). The effect of increased calcium intake on bone density does not appear to persist unless the higher intakes are sustained. There are certain conditions, such as lactation, during which calcium intake does not appear to influence bone. Other factors that may influence the effect of calcium on bone include bone-specific genotypes and physical activity.

Bone density in axial and appendicular skeleton in patients with lactose intolerance: influence of calcium intake and vitamin D status

BACKGROUND

Lactose intolerance (LI) is a common enzymatic insufficiency, manifesting by poor tolerance of dairy products, leading to low calcium intake and poor calcium absorption from dairy products. These changes might lead to an impairment of bone metabolism [1].

OBJECTIVES

To evaluate the impact of LI on quantitative bone parameters in axial and appendicular skeletal sites. To assess the impact of calcium intake from dairy and non-dairy nutritional sources, calcium regulating hormones and bone turnover on quantitative bone parameters in LI patients.

METHODS

We evaluated calcium intake and bone status in sixty-six patients with LI, 49 women and 17 men, aged 20 to 78. Bone mass was assessed at the lumbar spine (LS), total hip (TH) and femoral neck (FN) by dual-energy x-ray absorptiometry (DEXA) and at the radius, tibia, phalanx by quantitative ultrasound. Serum calcium, albumin, inorganic phosphate, calcium regulating hormones and markers of bone turnover were evaluated.

RESULTS

Total daily calcium intake was below the recommended by the American Dietetic Association [2] in all study participants (mean 692 mg/day +/- 162). Elevated level of urinary deoxypyridinoline crosslinks (DPD) was observed in 63 (96%) patients and was negatively correlated with total daily calcium intake (r = -0.998, p = 0.025) and with nondairy calcium intake (r = -0.34, p = 0.015). Parathyroid hormone (PTH) level in the upper third of normal range (45-65 ng/L) was observed in 11 (17%) patients. Parathyroid hormone (PTH) was inversely correlated with total calcium intake (r = -0.4, p = 0.001), dairy calcium intake (r = -0.83, p = 0.05), non-dairy calcium intake (r = -0.29, p = 0.043), 25OHD(3) serum level (r = -0.3, p = 0.007) and positively correlated with bone turnover markers (deoxypyridinoline crosslinks [DPD], r = 0.36, p = 0.01 and bone specific alkaline phosphatase [BSAP] r = 0.36, p = 0.01). Decrease in quantitative bone parameters compared to age-matched controls was observed in the axial and in the appendicular skeleton in men and in postmenopausal women: mean z-score for LS -0.87 +/- 0.22 and -1.32 +/- 0.65, p = 0.004 and 0.015, tibia -1.15 +/- 0.53 and -0.44 +/- 0.044, p < 0.001 and 0.27, phalanx -0.98 +/- 0.22 and -0.52 +/- 0.98, p < 0.001. We observed decrease in bone mass in patients with serum PTH in the upper tertile of normal range in the FN (z-score -0.57 +/- 0.6 versus -0.03 +/- 0.9, p = 0.025), TH (-0.51 +/- 0.96 versus 0.04 +/- 0.9, p = 0.05) and radius (-1.84 +/- 0.27 versus -0.07 +/- 1.61, p = 0.025, respectively). z-scores in FN and TH positively correlated with serum 25OHD(3) level (r = 0.31, 0.29; p = 0.014, 0.019). In postmenopausal women serum 25OHD(3) level correlated also with LS z-scores (r = 0.52, p = 0.004); FN and TH z-scores negatively correlated with DPD level (r = -0.51, p = 0.02 and r = -0.55, p = 0.04).

CONCLUSION

LI state may lead to increased bone turnover and decreased bone mass especially in men and postmenopausal women. Impaired vitamin D status and low calcium intake may be deleterious to bone in this condition.

Determinants of osteoporosis prevention in low-income Mexican-American women

BACKGROUND

Prevention is the most cost-effective means of managing osteoporosis. However, little is known about osteoporosis-related preventive practices in Mexican-American women. We examined factors that might influence women's decision to start preventive measures for osteoporosis.

METHODS

Information was gathered through a cross-sectional survey of low-income Mexican-American women who were seen at two clinics in southern Texas.

RESULTS

Of the 270 participants, 37% reported calcium supplementation, and 41% reported regular weight-bearing exercise to prevent osteoporosis. Fifty (41%) of the postmenopausal women were currently using hormone replacement therapy. Only 15% of the premenopausal and 13% of the postmenopausal women recalled that their health care provider had counseled them about prevention. Multivariate analysis showed that public education, bone densitometry evaluation, knowledge of osteoporosis, and counseling were determinants of prevention.

CONCLUSION

Although osteoporosis is a preventable condition, our findings suggest that the majority of Mexican-American women do not receive adequate preventive measures or counseling about osteoporosis. Furthermore, we found that their health care provider's counseling about osteoporosis was a major determinant of osteoporosis prevention in these women.

Children who avoid drinking cow milk have low dietary calcium intakes and poor bone health

BACKGROUND

Information concerning the adequacy of bone mineralization in children who customarily avoid drinking cow milk is sparse.

OBJECTIVE

The objective was to evaluate dietary calcium intakes, anthropometric measures, and bone health in prepubertal children with a history of long-term milk avoidance.

DESIGN

We recruited 50 milk avoiders (30 girls, 20 boys) aged 3-10 y by advertisement. We measured current dietary calcium intakes with a food-frequency questionnaire and body composition and bone mineral density with dual-energy X-ray absorptiometry and compared the results with those of 200 milk-drinking control children.

RESULTS

The reasons for milk avoidance were intolerance (40%), bad taste (42%), and lifestyle choice (18%). Dietary calcium intakes were low (443 +/- 230 mg Ca/d), and few children consumed substitute calcium-rich drinks or mineral supplements. Although 9 children (18%) were obese, the milk avoiders were shorter (P < 0.01), had smaller skeletons (P < 0.01), had a lower total-body bone mineral content (P < 0.01), and had lower z scores (P < 0.05) for areal bone mineral density at the femoral neck, hip trochanter, lumbar spine, ultradistal radius, and 33% radius than did control children of the same age and sex from the same community. The z scores for volumetric (size-adjusted) bone mineral density (g/cm(3)) were -0.72 +/- 1.17 for the lumbar spine and -0.72 +/- 1.35 for the 33% radius (P < 0.001). Twelve children (24%) had previously broken bones.

CONCLUSIONS

In growing children, long-term avoidance of cow milk is associated with small stature and poor bone health. This is a major concern that warrants further study.

A longitudinal study of bone density in midlife women

A longitudinal study of 386 healthy Black and White women aged 35-60 years was conducted to determine the effects of physical activity and other related factors on lumbar bone mineral density over 24 months. Bone mineral density of the lumbar spine, L2-L4, was measured using dual energy x-ray (Hologic 1000). Physical activity levels in three dimensions (leisure, household, and occupational) from both a lifelong and current perspective were obtained by questionnaire. Body mass index was calculated from measured weight in kilograms divided by measured height in meters squared. Calcium, caffeine, and alcohol intake was estimated using a food frequency questionnaire. Age, race, and smoking were determined by self-report. Radioimmunoassays of follicle stimulating hormone (FSH) and estradiol were used to validate self-reports of menopausal status. Multiple regression analysis revealed that race, age, weight, FSH, calcium, and years of tobacco intake formed the best model at baseline (r(2) = 0.32) and at 24 months (r(2) = 0.303). Physical activity was not a significant predictor for bone mineral density at either time point. There were cross-sectional changes of bone mineral density with race, age, and menopausal status. Black women had significantly higher bone mineral density than White women. However, an age-related decline in bone mineral density was exhibited in both Black and White women. Perimenopausal women had significantly lower bone mineral density as compared with premenopausal women. Furthermore 37 (9.6%) women at baseline and 34 (11%) at 24 months were designated at risk for fracture.