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Osteo_SS_kneejointdamageOsteoarthritis (OA) is a degenerative joint disease that mainly affects cartilage, causing functional limitation and disability particularly in the elderly. It is estimated that over 27 million individuals over the age of 65 suffer from osteoarthritis, which most commonly affects the knee. Vitamin D plays many biological and functional roles in joint health, so vitamin D status may play a role in the progression of knee osteoarthritis.

In a new study published online in the Journal of Nutrition, researchers investigated whether serum vitamin D and parathyroid hormone (PTH) concentrations might predict the progression of knee OA. PTH is responsible for regulating the metabolism of vitamin D. The study included 418 participants enrolled in the Osteoarthritis Initiative who had at least one knee with diagnosed osteoarthritis. Serum vitamin D and PTH were measured at the 30 or 36 month visit of the study, and progression of OA was defined as an increase in the joint space narrowing (JSN) score between the 2 and 4 year study visits.

The average serum vitamin D level of the participants was 26 ng/ml, while 16% of this population had levels below 15 ng/ml. Between the beginning of the study and follow-up visits, 14% of the subjects experienced joint space narrowing (increased JSN score). Subjects with a low vitamin D level (< 15 ng/ml) had twice the risk of elevated knee OA progression than the participants with vitamin D levels > 15 ng/ml. Although a high serum PTH itself was not associated with a significant increase in JSN score, individuals with both low vitamin D and high PTH (> 73 pg/ml) had a greater than 3 fold increased risk of OA progression.

The results of the present study suggest that individuals deficient in vitamin D have greater risk of osteoarthritis progression than those with normal vitamin D levels.

Fang Fang Zhang et al. J Nutr. 2014; 144(12):2002-8. doi: 10.3945/jn.114.193227.

Child obeseSeveral B vitamins play important roles in the metabolism of carbohydrates, proteins, fats, and the health of mitochondria, which are involved in energy metabolism. Previous research has indicated that insufficient micronutrient intake can be a contributing factor in childhood obesity, but the results of research have been somewhat inconsistent.

In a new study published in the Journal of Nutrition, researchers examined the associations between serum vitamin B12 and folate concentrations, and intakes of select B vitamins with body fat. Subjects included 1,131 Mexican American children 8-15 yrs. of age who participated in the National Health and Nutrition Examination Survey (NHANES) 2001-2004. Blood samples were analyzed for serum vitamin B12 and folate levels, and dietary questionnaire responses provided information concerning B vitamin intake. Dexa scans of fat mass and total body fat mass were used along with BMI as measures of body fat.

Body mass index, trunk fat mass and total body fat mass increased with age, but children with higher serum levels of B12 and folate had lower measures of BMI, trunk fat and total body fat. Children with normal weight had higher serum B12 levels compared to overweight or obese children. Analysis of B vitamin intake showed that children with higher intakes of thiamin (B1) and riboflavin (B2) were more likely to have a healthy BMI and lower body trunk fat mass.

The results of this study showing the inverse relationship between the status of B12, folate, riboflavin and thiamin suggest that these micronutrients may play a role in the risk reduction of childhood obesity.

Inong R Gunanti et al. J Nutr. 2014 Dec; 144(12):2027-33. doi: 10.3945/jn.114.201202.

Healthy ManIt is known that a high glycemic index (GI) carbohydrate content in the diet increases insulin levels and can potentially impair fat oxidation. In a new study published in the European Journal of Clinical Nutrition, researchers theorized that refeeding a low GI, moderate carbohydrate diet would improve chances of weight maintenance.

The study involved 32 healthy young men (average 26 years of age) who were not overweight (average BMI 23 kg/m2). For one week, they were overfed at a level of 50% higher than their caloric needs, followed by a three-week caloric restricted diet (-50% of their energy needs). They were then overfed for two weeks at +50% of energy requirement, and given either a low GI (41) or high GI diet (74) and moderate versus high carbohydrate (CHO) intake (50% vs 65% of energy intake). Fat mass and adaptation of fasting macronutrient oxidation were measured.

During the first overfeeding, the subjects gained an average of 1.9 kg body weight, followed by an average weight loss of 6.3 kg while on caloric restricted diet. During the last overfeeding the subjects gained back an average of 2.8 kg. Subjects eating the higher CHO (65%) diet gained more body weight compared to the 50% CHO diet, especially when eating the high GI meals. Re-feeding the high GI diet impaired fat oxidation compared to the low GI diet. The impairment in fasting fat oxidation was correlated with regain in fat mass and body weight. Metabolic impairment after eating the 50% CHO was not significant.

The results of this study show that both higher GI and higher carbohydrate intake can negatively affect fat oxidation leading to body weight regain in healthy men. A lower glycemic index and glycemic load diet enhances the ability to maintain weight after weight loss.

J Kahlhöfer et al.; European Journal of Clinical Nutrition (2014); 68:1060–1066; doi:10.1038/ejcn.2014.132.

AvocadoBone fractureRecent studies have indicated that oxidative stress may be a contributing factor in the development of osteoporosis and fractures. A new study investigated the potential association between serum alpha-tocopherol (Vitamin E) concentrations and the risk of hip fractures.

The study, published online in the journal Osteoporosis International, included 21,774 Norwegian men and women aged 65-79 that were part of a community-based health study. Serum Vitamin E concentrations were measured at the beginning of the study and subjects were followed for 11 years.

During the course of the follow up, 1,168 hip fractures were reported in the men and women. After adjusting for smoking, month of blood sample, BMI, education, physical inactivity, self-rated health, and serum 25-hydroxyvitamin D (25(OH)D), serum vitamin E levels showed a linear inverse association with hip fracture risk. Among subjects in the lowest quartile (25%) of serum Vitamin E, the risk of hip fracture was 51% higher than those whose levels were among the top 25%.

In this older population, low serum vitamin E concentrations were associated with an increased risk of hip fractures. These results confirm the findings of two recent cohort studies which also found an increased risk of bone fracture among older adults with low serum vitamin E concentrations. The researchers suggest that in addition to its antioxidant effect, vitamin E could have a direct role in bone remodeling. However, further research is needed to clarify the role of vitamin E in maintaining bone health.

Holvik K et al. Osteoporos Int. 2014 Nov; 25(11):2545-54. doi:10.1007/s00198-014-2802-6.

Michaëlsson K et al. Am J Clin Nutr. 2014 Jan; 99(1):107-14. doi:10.3945/ajcn.113.064691

vitamin-d-sourcesA study published in the American Journal of Clinical Nutrition has shown a reduction in cancer rates among postmenopausal women taking vitamin D combined with calcium.

This four-year, double blind, randomized placebo-controlled study involved over 1,100 postmenopausal women who were divided into three treatment groups: 1) placebo, consisting of both a vitamin D placebo and a calcium placebo; 2) calcium, consisting of either calcium citrate (1400 mg Ca/day) or calcium carbonate (1500 mg Ca/day) plus a vitamin D placebo (Ca-only group); and 3) calcium plus vitamin D, consisting of calcium plus 1000 IU (25 μg) Vitamin D3/day (Ca + D group).

In comparison to the placebo group, the women taking both calcium and vitamin D had a 60% decreased risk of all cancer by the end of the study. There was also a marginal reduction in risk among the women taking calcium only.

This study takes an important step in extending several decades of research involving the role of vitamin D in health and disease. The results further strengthen the case made by many specialists that vitamin D may be a powerful cancer preventive and that it is commonly found lacking in the general population, particularly the elderly.

Joan M Lappe et al. Am J Clin Nutr June 2007. Vol. 85(6):1586-1591

LemonPrevious observational studies have suggested that a higher intake of vitamin C is associated with a reduced risk of cardiovascular disease, primarily through effects on the endothelium (a thin layer of cells lining the interior of blood vessels). The endothelium has many important functions that include maintaining the flexibility of blood vessels and modulating the activity of certain white blood cells that are a significant part of the immune system.

In a recent meta-analysis published in the journal Atherosclerosis, researchers sought to determine the effect of vitamin C supplementation on endothelial function (EF) in adults, and whether the outcome differed by health status, study duration, dose and route of administration.

The study included 44 clinical trials and 1,129 adult participants. Supplemental vitamin C at oral doses of more than 500 mg was associated with significant improvement of endothelial function in subjects with cardio-metabolic disorders. The benefits of supplementation were primarily limited to people with atherosclerosis, diabetes, and heart failure. The study design, duration of supplementation, route of administration and baseline plasma vitamin C did not appear to significantly affect the outcome. There was a significant positive association between dosages greater than 500 mg/day and improvement in endothelial function.

The researchers noted that in addition to its effects on oxidative stress, vitamin C may positively affect nitric oxide, a potent vasodilator, reducing vascular inflammation. The results of this study indicate that vitamin C supplementation may improve endothelial function, especially in adults with a higher cardiovascular risk. Vitamin C supplementation, therefore, could potentially be a useful tool for the secondary prevention of cardiovascular diseases.

Ashor AW et al. Atherosclerosis.2014 Jul; 235(1):9-20.

Magnesium (Mg) is an essential mineral important in the structure and the function of the human body and also as a cofactor for hundreds of enzyme systems that regulate diverse biochemical reactions in the body. Unfortunately, dietary surveys in the US continue to show that older people are particularly susceptible to magnesium deficiency for various reasons, including an inadequate dietary intake, reduced absorption, and greater losses in stools and urine. A poor magnesium status has been associated with reduced physical performance, but to date no trials have established a link between magnesium supplementation and physical performance in the elderly.

In a new study published in the American Journal of Clinical Nutrition, investigators sought to determine whether oral magnesium supplementation could improve physical performance in healthy older women. 124 healthy women (average age: 71.5 years) attending a mild fitness program were randomly assigned into two groups: 54 women in the treatment group were given 300 mg/day of magnesium oxide for 12 weeks, and 77 in the control group received no placebo or intervention. The primary outcome was a change in the Short Physical Performance Battery (SPPB).

The scores for the SPPB did not differ between the two groups at baseline. After 12 weeks, the group taking magnesium had a significantly better total SPPB score than the controls. The treatment group also had a significantly better test score for chair stand times and 4 minute walking speeds. The improvements were more evident in women with dietary magnesium intakes below the RDA.

The findings of this study indicate that magnesium supplementation may play a role in delaying age-related decline in physical performance in healthy older women, especially if dietary intake is below recommended levels.

Nicola Veronese et al. Am J Clin Nutr. 2014 Sep;100(3):974-81. doi: 10.3945/ajcn.113.080168.

Type 2 diabetesType 2 diabetes has become a significant worldwide health care challenge, as it is associated with various health problems and increased mortality risk. There is increasing evidence that vitamin D influences many non-skeletal medical conditions, including heart disease, cancer, certain autoimmune diseases and type-2 diabetes. Observational research has shown that seasonal variation in blood sugar control in the winter may be partly due to vitamin D, since vitamin D levels are generally much lower in the winter.

In a study published in the European Journal of Clinical Nutrition, researchers examined the association between vitamin D status and the incidence of Type 2 diabetes. After a thorough review of the literature, 8 observational studies and 11 randomly controlled trials were included in the review.

Intake of >500 IU/day decreased the risk of type 2 diabetes by 13% when compared to those with a vitamin D intake of <200 IU/day; Adults with the highest vitamin D status (>25 ng/ml or 62.5 mmol/L) had a 43% lower risk of developing type 2 diabetes when compared to those with the lowest serum vitamin D levels (<14 ng/ml or 35 mmol/L). In two trials that included patients with glucose intolerance, vitamin D supplementation improved measures of insulin resistance. No significant effect of vitamin D on glycemic outcomes was evident in the trials that included subjects with normal glucose tolerance at baseline.

The results of this review show that vitamin D may play a role in the prevention of type 2 diabetes, although high-quality studies are needed to determine a potential mechanism between vitamin D concentration and relevant glycemic outcomes.

J Mitri et al. European Journal of Clinical Nutrition (2011) 65:1005–1015.

The attenuation of the number and severity of infections is of importance to athletes. Probiotics use has increased over recent years with beneficial effects believed to include improvements in immune function. Recent research has focused on their effectiveness for reducing the number, duration and severity of infections amongst endurance athletes. At present no research has been undertaken with team sport athletes.

Scientist from University of Otago conducted a randomised controlled trial aimed to determine the effectiveness of probiotics on the number, duration and severity of infections amongst elite union rugby players. Thirty elite rugby union players were allocated randomly to receive either a daily probiotics supplement (containing lactobacillus gasseri, Bifidobacterium bifidium and B. Longum) or a placebo for four weeks. Participants completed a daily diary to identify and rate the severity of any infectious symptoms.

During the probiotic treatment 14/30 participants never experienced a single upper respiratory tract illness (URTI) or gastrointestinal (GI) episode, compared to 6/30 on the placebo supplementation. The duration of infection was also significantly reduced in probiotic supplement group (3.4 days) compared to the placebo group (5.8 days). There was no significant difference in the severity of the symptoms between the two treatment groups.

These results provide evidence for the beneficial effects of daily probiotic supplementation in professional rugby union players who undertake intensive training and competition.

Brylee A Haywood et al. J Science and Medicine in Sport July 2014; Vol. 17(4):356–360

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