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Nutrients, Volume 2, Issue 9 (September 2010), Pages 929-1043

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Research

Jump to: Review

Open AccessArticle Reexamination of a Meta-Analysis of the Effect of Antioxidant Supplementation on Mortality and Health in Randomized Trials
Nutrients 2010, 2(9), 929-949; doi:10.3390/nu2090929
Received: 16 July 2010 / Revised: 17 August 2010 / Accepted: 26 August 2010 / Published: 30 August 2010
Cited by 21 | PDF Full-text (267 KB) | HTML Full-text | XML Full-text
Abstract
A recent meta-analysis of selected randomized clinical trials (RCTs), in which population groups of differing ages and health status were supplemented with various doses of b-carotene, vitamin A, and/or vitamin E, found that these interventions increased all-cause mortality. However, this meta-analysis did [...] Read more.
A recent meta-analysis of selected randomized clinical trials (RCTs), in which population groups of differing ages and health status were supplemented with various doses of b-carotene, vitamin A, and/or vitamin E, found that these interventions increased all-cause mortality. However, this meta-analysis did not consider the rationale of the constituent RCTs for antioxidant supplementation, none of which included mortality as a primary outcome. As the rationale for these trials was to test the hypothesis of a potential benefit of antioxidant supplementation, an alternative approach to a systematic evaluation of these RCTs would be to evaluate this outcome relative to the putative risk of greater total mortality. Thus, we examined these data based on the primary outcome of the 66 RCTs included in the meta-analysis via a decision analysis to identify whether the results provided a positive (i.e., benefit), null or negative (i.e., harm) outcome. Our evaluation indicated that of these RCTs, 24 had a positive outcome, 39 had a null outcome, and 3 had a negative outcome. We further categorized these interventions as primary (risk reduction in healthy populations) or secondary (slowing pathogenesis or preventing recurrent events and/or cause-specific mortality) prevention or therapeutic (treatment to improve quality of life, limit complications, and/or provide rehabilitation) studies, and determined positive outcomes in 8 of 20 primary prevention studies, 10 of 34 secondary prevention studies, and 6 out of 16 therapeutic studies. Seven of the eight RCTs with a positive outcome in primary prevention included participants in a population where malnutrition is frequently described. These results suggest that analyses of potential risks from antioxidant supplementation should be placed in the context of a benefit/risk ratio. Full article
(This article belongs to the Special Issue Dietary Antioxidants)
Open AccessArticle Calcium Intake and Body Composition in African-American Children and Adolescents at Risk for Overweight and Obesity
Nutrients 2010, 2(9), 950-964; doi:10.3390/nu2090950
Received: 27 July 2010 / Revised: 27 August 2010 / Accepted: 9 September 2010 / Published: 10 September 2010
Cited by 5 | PDF Full-text (356 KB) | HTML Full-text | XML Full-text
Abstract
This study examined the role of calcium intake on body composition in 186 African-American adolescents at risk for overweight and obesity. The average weight of 89.8 kg ± 23.6 (SD) had a mean BMI z score of 2.2. Females with a calcium intake of < 314 mg/day had higher percent fat mass compared to those with the highest calcium intakes that were ≥ 634 mg/day. Compared to those with a low calcium intake (< 365 mg/day), those with the highest calcium intake of > 701 mg/day had higher intake of thiamin, folate, cobalamin, vitamin D, phosphorus, iron, zinc. Full article
(This article belongs to the Special Issue Dietary Calcium)
Open AccessArticle Bone Density Testing: An Under-Utilised and Under-Researched Health Education Tool for Osteoporosis Prevention?
Nutrients 2010, 2(9), 985-996; doi:10.3390/nu2090985
Received: 3 August 2010 / Revised: 18 August 2010 / Accepted: 20 August 2010 / Published: 16 September 2010
Cited by 4 | PDF Full-text (198 KB) | HTML Full-text | XML Full-text
Abstract
Feedback of fracture risk based on bone mineral density (BMD) is an under-explored potential osteoporosis education intervention. We performed a randomised controlled trial of either an osteoporosis information leaflet or small group education (the Osteoporosis Prevention and Self-Management Course (OPSMC)), combined with individualised fracture risk feedback in premenopausal women over two years. Women with a mean T-score at spine and hip of < 0 were informed they were at higher risk of fracture in later life and those with T-score ≥ 0 were informed they were not. Women receiving feedback of high fracture risk had a greater increase in femoral neck, but not lumbar spine, BMD compared to the low risk group (1.6% p.a. vs. 0.7% p.a., p = 0.0001). Participation in the OPSMC had no greater effect on BMD than receiving the leaflet. Femoral neck BMD change was associated with starting calcium supplements (1.3% p.a., 95% CI +0.49, +2.17) and self-reported physical activity change (0.7% p.a., 95% CI +0.22, +1.22). Mother’s report of increasing their children’s calcium intake was associated with receiving the OPSMC (OR 2.3, 95% CI 1.4, 3.8) and feedback of high fracture risk (OR 2.0, 95% CI 1.2, 3.3). Fracture risk feedback based on BMD could potentially make an important contribution to osteoporosis prevention but confirmation of long-term benefits and cost effectiveness is needed before implementation can be recommended. Full article
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Open AccessArticle Annual Feedback Is an Effective Tool for a Sustained Increase in Calcium Intake among Older Women
Nutrients 2010, 2(9), 1018-1025; doi:10.3390/nu2091018
Received: 3 August 2010 / Revised: 15 August 2010 / Accepted: 20 August 2010 / Published: 17 September 2010
Cited by 6 | PDF Full-text (121 KB) | HTML Full-text | XML Full-text
Abstract
We aimed to optimize calcium intake among the 2,000+ older women taking part in the Vital D study. Calcium supplementation was not included in the study protocol. Our hypothesis was that annual feedback of calcium intake and informing women of strategies to improve calcium intake can lead to a sustained increase in the proportion of women who consume adequate levels of the mineral. Calcium intake was assessed on an annual basis using a validated short food frequency questionnaire (FFQ). Supplemental calcium intake was added to the dietary estimate. Participants and their nominated doctor were sent a letter that the participant’s estimated daily calcium intake was adequate or inadequate based on a cutoff threshold of 800 mg/day. General brief statements outlining the importance of an adequate calcium intake and bone health were included in all letters. At baseline, the median daily consumption of calcium was 980 mg/day and 67 percent of 1,951 participants had calcium intake of at least 800 mg per day. Of the 644 older women advised of an inadequate calcium intake at baseline (< 800 mg/day), 386 (60%) had increased their intake by at least 100 mg/day when re-assessed twelve months later. This desirable change was sustained at 24 months after baseline with almost half of these women (303/644) consuming over 800 mg calcium per day. This study devised an efficient method to provide feedback on calcium intake to over 2,000 older women. The improvements were modest but significant and most apparent in those with a low intake at baseline. The decreased proportion of these women with an inadequate intake of calcium 12- and 24-months later, suggests this might be a practical, low cost strategy to maintain an adequate calcium intake among older women. Full article
Open AccessCommunication Calcium Intake in Elderly Australian Women Is Inadequate
Nutrients 2010, 2(9), 1036-1043; doi:10.3390/nu2091036
Received: 3 August 2010 / Revised: 24 August 2010 / Accepted: 27 August 2010 / Published: 17 September 2010
Cited by 6 | PDF Full-text (146 KB) | HTML Full-text | XML Full-text
Abstract
The role of calcium in the prevention of bone loss in later life has been well established but little data exist on the adequacy of calcium intakes in elderly Australian women. The aim of this study was to compare the dietary intake [...] Read more.
The role of calcium in the prevention of bone loss in later life has been well established but little data exist on the adequacy of calcium intakes in elderly Australian women. The aim of this study was to compare the dietary intake including calcium of elderly Australian women with the Australian dietary recommendation, and to investigate the prevalence of calcium supplement use in this population. Community-dwelling women aged 70–80 years were randomly recruited using the Electoral Roll for a 2-year protein intervention study in Western Australia. Dietary intake was assessed at baseline by a 3-day weighed food record and analysed for energy, calcium and other nutrients. A total of 218 women were included in the analysis. Mean energy intake was 7,140 ± 1,518 kJ/day and protein provided 19 ± 4% of energy. Mean dietary calcium intake was 852 ± 298 mg/day, which is below Australian recommendations. Less than one quarter of women reported taking calcium supplements and only 3% reported taking vitamin D supplements. Calcium supplements by average provided calcium 122 ± 427 mg/day and when this was taken into account, total calcium intake increased to 955 ± 504 mg/day, which remained 13% lower than the Estimated Average Requirement (EAR, 1,100 mg/day) for women of this age group. The women taking calcium supplements had a higher calcium intake (1501 ± 573 mg) compared with the women on diet alone (813 ± 347 mg). The results of this study indicate that the majority of elderly women were not meeting their calcium requirements from diet alone. In order to achieve the recommended dietary calcium intake, better strategies for promoting increased calcium, from both diet and calcium supplements appears to be needed. Full article

Review

Jump to: Research

Open AccessReview Long-Chain Polyunsaturated Fatty Acids in Inborn Errors of Metabolism
Nutrients 2010, 2(9), 965-974; doi:10.3390/nu2090965
Received: 4 August 2010 / Revised: 6 September 2010 / Accepted: 13 September 2010 / Published: 15 September 2010
Cited by 3 | PDF Full-text (240 KB) | HTML Full-text | XML Full-text
Abstract
The treatment of children with inborn errors of metabolism (IEM) is mainly based on restricted dietary intake of protein-containing foods. However, dietary protein restriction may not only reduce amino acid intake, but may be associated with low intake of polyunsaturated fatty acids [...] Read more.
The treatment of children with inborn errors of metabolism (IEM) is mainly based on restricted dietary intake of protein-containing foods. However, dietary protein restriction may not only reduce amino acid intake, but may be associated with low intake of polyunsaturated fatty acids as well. This review focuses on the consequences of dietary restriction in IEM on the bioavailability of long-chain polyunsaturated fatty acids (LCPUFAs) and on the attempts to ameliorate these consequences. We were able to identify during a literature search 10 observational studies investigating LCPUFA status in patients with IEM and six randomized controlled trials (RCTs) reporting effect of LCPUFA supplementation to the diet of children with IEM. Decreased LCPUFA status, in particular decreased docosahexaenoic acid (DHA) status, has been found in patients suffering from IEM based on the evidence of observational studies. LCPUFA supplementation effectively improves DHA status without detectable adverse reactions. Further research should focus on functional outcomes of LCPUFA supplementation in children with IEM. Full article
(This article belongs to the Special Issue Paediatric Nutrition and Metabolism)
Open AccessReview Prevention of Fractures in Older People with Calcium and Vitamin D
Nutrients 2010, 2(9), 975-984; doi:10.3390/nu2090975
Received: 3 August 2010 / Revised: 18 August 2010 / Accepted: 23 August 2010 / Published: 16 September 2010
Cited by 8 | PDF Full-text (106 KB) | HTML Full-text | XML Full-text
Abstract
The greatest cause of fracture in older people is osteoporosis which contributes to increased morbidity and mortality in older people. A number of meta-analyses have been performed assessing the effectiveness of calcium supplementation alone, vitamin D supplementation alone and the combined therapy [...] Read more.
The greatest cause of fracture in older people is osteoporosis which contributes to increased morbidity and mortality in older people. A number of meta-analyses have been performed assessing the effectiveness of calcium supplementation alone, vitamin D supplementation alone and the combined therapy on bone loss and fracture reduction in older people. The results of these meta-analyses indicate that vitamin D supplementation alone is unlikely to reduce fracture risk, calcium supplementation alone has a modest effect in reducing total fracture risk, but compliance with calcium supplements is poor in the long term. The combination of calcium supplementation with vitamin D supplementation, particularly in those at risk of marginal and low vitamin D status reduces total fractures, including hip fractures. Therefore older people would be recommended to consume adequate dietary calcium (>1100 mg/day) together with maintaining adequate vitamin D status (>60 nmol/L 25(OH)D) to reduce risk of fracture. It is a challenge to consume sufficient dietary calcium from dietary sources, but the increasing range of calcium fortified foods could assist in increasing the dietary calcium intake of older people. In addition to the usual dairy based food sources, vitamin D supplements are likely to be required for older people with reduced mobility and access to sunlight. Full article
Open AccessReview Evolution of the Calcium Paradigm: The Relation between Vitamin D, Serum Calcium and Calcium Absorption
Nutrients 2010, 2(9), 997-1004; doi:10.3390/nu2090997
Received: 3 August 2010 / Revised: 18 August 2010 / Accepted: 24 August 2010 / Published: 16 September 2010
Cited by 10 | PDF Full-text (101 KB) | HTML Full-text | XML Full-text
Abstract
Osteoporosis is the index disease for calcium deficiency, just as rickets/osteomalacia is the index disease for vitamin D deficiency, but there is considerable overlap between them. The common explanation for this overlap is that hypovitaminosis D causes malabsorption of calcium which then [...] Read more.
Osteoporosis is the index disease for calcium deficiency, just as rickets/osteomalacia is the index disease for vitamin D deficiency, but there is considerable overlap between them. The common explanation for this overlap is that hypovitaminosis D causes malabsorption of calcium which then causes secondary hyperparathyroidism and is effectively the same thing as calcium deficiency. This paradigm is incorrect. Hypovitaminosis D causes secondary hyperparathyroidism at serum calcidiol levels lower than 60 nmol/L long before it causes malabsorption of calcium because serum calcitriol (which controls calcium absorption) is maintained until serum calcidiol falls below 20 nmol/L. This secondary hyperparathyroidism, probably due to loss of a “calcaemic” action of vitamin D on bone first described in 1957, destroys bone and explains why vitamin D insufficiency is a risk factor for osteoporosis. Vitamin D thus plays a central role in the maintenance of the serum (ionised) calcium, which is more important to the organism than the preservation of the skeleton. Bone is sacrificed when absorbed dietary calcium does not match excretion through the skin, kidneys and bowel which is why calcium deficiency causes osteoporosis in experimental animals and, by implication, in humans. Full article
Open AccessReview Independent and Combined Effects of Exercise and Vitamin D on Muscle Morphology, Function and Falls in the Elderly
Nutrients 2010, 2(9), 1005-1017; doi:10.3390/nu2091005
Received: 3 August 2010 / Revised: 17 August 2010 / Accepted: 21 August 2010 / Published: 16 September 2010
Cited by 9 | PDF Full-text (251 KB) | HTML Full-text | XML Full-text
Abstract
Regular exercise, particularly progressive resistance training (PRT), is recognized as one of the most effective strategies to prevent age-related muscle loss (sarcopenia), but its effects on muscle function are mixed. However, emerging data indicates that high velocity PRT (fast concentric muscle contractions) [...] Read more.
Regular exercise, particularly progressive resistance training (PRT), is recognized as one of the most effective strategies to prevent age-related muscle loss (sarcopenia), but its effects on muscle function are mixed. However, emerging data indicates that high velocity PRT (fast concentric muscle contractions) is more effective for improving functional outcomes than traditional PRT. In terms of falls prevention, high-challenging balance training programs appear to be most effective. There is also compelling evidence that supplemental vitamin D is an effective therapeutic option for falls prevention. The findings from a recent meta-analysis revealed that supplemental vitamin D at a dose of at least 700–1,000 IU/d or an achieved serum 25(OH)D level of at least 60 nmol/L was associated with reduced falls risk among older individuals. Based on these findings, it is possible that the combination of exercise and vitamin D could have a synergistic effect on muscle morphology and function, particularly since both interventions have been shown to have beneficial effects on type II “fast twitch” muscle fibers and systemic inflammation, which have both been linked to losses in muscle mass and function. Unfortunately however, the findings from the limited number of factorial 2 × 2 design RCTs indicate that additional vitamin D does not enhance the effects of exercise on measures of muscle morphology, function or falls risk. However, none of these trials were adequately powered to detect a “synergistic” effect between the two treatment strategies, but it is likely that if an exercise-by-vitamin D interaction does exist, it may be limited to situations when vitamin D deficiency/insufficiency is corrected. Further targeted research in “high risk” groups is still needed to address this question, and evaluate whether there is a threshold level of serum 25(OH)D to maximize the effects of exercise on muscle and falls risk. Full article
Open AccessReview Experimental Evidence for the Effects of Calcium and Vitamin D on Bone: A Review
Nutrients 2010, 2(9), 1026-1035; doi:10.3390/nu2091026
Received: 3 August 2010 / Revised: 19 August 2010 / Accepted: 23 August 2010 / Published: 17 September 2010
Cited by 6 | PDF Full-text (349 KB) | HTML Full-text | XML Full-text
Abstract
Animal models fed low calcium diets demonstrate a negative calcium balance and gross bone loss while the combination of calcium deficiency and oophorectomy enhances overall bone loss. Following oophorectomy the dietary calcium intake required to remain in balance increases some 5 fold, [...] Read more.
Animal models fed low calcium diets demonstrate a negative calcium balance and gross bone loss while the combination of calcium deficiency and oophorectomy enhances overall bone loss. Following oophorectomy the dietary calcium intake required to remain in balance increases some 5 fold, estimated to be approximately 1.3% dietary calcium. In the context of vitamin D and dietary calcium depletion, osteomalacia occurs only when low dietary calcium levels are combined with low vitamin D levels and osteoporosis occurs with either a low level of dietary calcium with adequate vitamin D status or when vitamin D status is low in the presence of adequate dietary calcium intake. Maximum bone architecture and strength is only achieved when an adequate vitamin D status is combined with sufficient dietary calcium to achieve a positive calcium balance. This anabolic effect occurs without a change to intestinal calcium absorption, suggesting dietary calcium and vitamin D have activities in addition to promoting a positive calcium balance. Each of the major bone cell types, osteoblasts, osteoclasts and osteocytes are capable of metabolizing 25 hydroxyvitamin D (25D) to 1,25 dihydroxyvitamin D (1,25D) to elicit biological activities including reduction of bone resorption by osteoclasts and to enhance maturation and mineralization by osteoblasts and osteocytes. Each of these activities is consistent with the actions of adequate circulating levels of 25D observed in vivo. Full article
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