Tag Archives: negative

Probiotics + FOS-Inulin Decreases Osteocalcin in Aged Rats

Abstract

Changes in calcium status in aged rats fed Lactobacillus GG and Bifidobacterium lactis and oligofructose-enriched inulin.

In this study we hypothesized that an increase in numbers of beneficial bacteria in the large intestine can affect calcium (Ca) status in the elderly. Adult and aged rats were fed a diet with or without synbiotics for 21 days. Synbiotics increased the numbers of lactobacilli and bifidobacteria in large intestine in both adult and aged rats. The plasma Ca concentration was significantly increased while osteocalcin concentration was significantly decreased only in aged rats fed synbiotics.

Naughton V, McSorley E, Naughton PJ
Appl Physiol Nutr Metab Feb 2011
PMID: 21326391

Alendronate Suppresses Bone Formation From Exercise in Rats

Abstract

Cancellous bone formation response to simulated resistance training during disuse is blunted by concurrent alendronate treatment.

The purpose of this study was to assess the effectiveness of simulated resistance training (SRT) exercise combined with alendronate (ALEN) in mitigating or preventing disuse-associated losses in cancellous bone microarchitecture and formation. Sixty male Sprague-Dawley rats (6 months old) were randomly assigned to either cage control (CC), hind limb unloading (HU), HU plus either ALEN (HU + ALEN), SRT (HU + SRT), or a combination of ALEN and SRT (HU + SRT/ALEN) for 28 days. HU + SRT and HU + SRT/ALEN rats were anesthetized and subjected to muscle contractions once every 3 days during HU (four sets of five repetitions, 1000 ms isometric + 1000 ms eccentric). Additionally, HU + ALEN and HU + SRT/ALEN rats received 10 µg/kg of body weight of ALEN three times per week. HU reduced cancellous bone-formation rate (BFR) by 80%, with no effect of ALEN treatment (-85% versus CC). SRT during HU significantly increased cancellous BFR by 123% versus CC, whereas HU + SRT/ALEN inhibited the anabolic effect of SRT (-70% versus HU + SRT). SRT increased bone volume and trabecular thickness by 19% and 9%, respectively, compared with CC. Additionally, osteoid surface (OS/BS) was significantly greater in HU + SRT rats versus CC (+32%). Adding ALEN to SRT during HU reduced Oc.S/BS (-75%), Ob.S/BS (-72%), OS/BS (-61%), and serum TRACP5b (-36%) versus CC. SRT and ALEN each independently suppressed a nearly twofold increase in adipocyte number evidenced with HU and inhibited increases in osteocyte apoptosis. These results demonstrate the anabolic effect of a low volume of high-intensity muscle contractions during disuse and suggest that both bone resorption and bone formation are suppressed when SRT is combined with bisphosphonate treatment.

Swift JM, Swift SN, Nilsson MI, Hogan HA…
J. Bone Miner. Res. Sep 2011
PMID: 21509821

Biking Lowers Bone Density in Men; Cyclists 7x More Likely to Have Osteopenia

Abstract

Participation in road cycling vs running is associated with lower bone mineral density in men.

The effects of regular non-weight-bearing (NWB) exercise on bone health are largely unknown. The objective of the study was to determine the effects of participation in NWB sports on bone health in adult male recreational athletes. Male cyclists (NWB; n = 27) and runners (weight-bearing [WB]; n = 16) aged 20 to 59 years were recruited from the community. Whole-body and regional bone mineral content and bone mineral density (BMD), and body composition were assessed using dual x-ray absorptiometry. Bone formation and resorption markers, and hormones were measured in serum. Bone-loading history was estimated from a sports participation history questionnaire. Nutrient intake and current physical activity were estimated from 7-day written logs. The NWB athletes had significantly lower BMD of the whole body and spine than the WB athletes, despite having similar age, weight, body mass index, body composition, hormonal status, current activity level, and nutrient intakes. Sixty-three percent of NWB athletes had osteopenia of the spine or hip, compared with 19% of WB athletes. Cyclists were 7 times more likely to have osteopenia of the spine than runners, controlling for age, body weight, and bone-loading history. There were no group differences in serum markers of bone turnover. Based on the results of this study, current bone loading is an important determinant of whole-body and lumbar spine BMD. Therefore, bone-loading activity should be sustained during adulthood to maintain bone mass.

Rector RS, Rogers R, Ruebel M, Hinton PS
Metab. Clin. Exp. Feb 2008
PMID: 18191053

Chocolate Bad for Bones

Abstract

Chocolate consumption and bone density in older women.

Nutrition is important for the development and maintenance of bone structure and for the prevention of osteoporosis and fracture. The relation of chocolate intake with bone has yet to be investigated.
We investigated the relation of chocolate consumption with measurements of whole-body and regional bone density and strength.
Randomly selected women aged 70-85 y (n=1460) were recruited from the general population to a randomized controlled trial of calcium supplementation and fracture risk. We present here a cross-sectional analysis of 1001 of these women. Bone density and strength were measured with the use of dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, and quantitative ultrasonography. Frequency of chocolate intake was assessed with the use of a questionnaire and condensed into 3 categories: or=1 time/d.
Higher frequency of chocolate consumption was linearly related to lower bone density and strength (P<0.05). Daily (>or=1 times/d) consumption of chocolate, in comparison to Older women who consume chocolate daily had lower bone density and strength. Additional cross-sectional and longitudinal studies are needed to confirm these observations. Confirmation of these findings could have important implications for prevention of osteoporotic fracture.

Hodgson JM, Devine A, Burke V, Dick IM…
Am. J. Clin. Nutr. Jan 2008
PMID: 18175753 | Free Full Text

This is disappointing. Cocoa is normally so healthy. My first thought was that they may be seeing the effects of sugar. Reading the full study, which is available for free using the link above, the authors made these comments:

Chocolate is usually also rich in sugar and contains the methylxanthines, theobromine and caffeine (27), and oxalate (11, 12)….

Oxalate is a potent inhibitor of calcium absorption (13). Furthermore, a single 100-g dose of dark chocolate was found to increase calcium excretion by 147% (14). The basis for this is not clear, but it is likely to include an effect of sugar to increase urinary calcium excretion (14, 15), dependent in part on an increase in plasma insulin that itself stimulates calciuria (29).

I wonder what would happen if you consumed a very dark chocolate (so very low in sugar) and supplemented calcium and vitamin D? The idea being that the very dark chocolate would avoid most of the sugar, and the calcium and vitamin D would hopefully overcome the reduced calcium absorption.