NUTRITION – PROTEIN – OSTEOPOROSIS – AGING


4 RESEARCH ARTICLES + 4 GRAPHICS – CLICK ON GRAPHIC TO ENLARGE



THE EFFECT OF WHEY PROTEIN ON BONE MASS IN OLDER ADULTS – 2015
Kerstetter JE1,  Insogna KL1.
CONTEXT
– It has been assumed the increase in urine calcium (Ca) that accompanies an increase in protein was due to increased bone resorption
– However, studies have found that protein increases Ca absorption without increasing bone resorption
OBJECTIVE
– Investigate the impact of a moderately high protein diet on bone mineral density (BMD)
METHODS
– 208 older women and men with a self-reported protein intake between 0.6 and 1.0 g/kg
– 45g whey protein or isocaloric maltodextrin supplement into their usual diet for 18 months
RESULTS
– No significant differences between groups for changes in L-spine BMD (primary outcome) or the other skeletal sites
– Truncal lean mass was significantly higher in the protein group at 18 months
– C-terminal telopeptide, IGF-1, and urinary urea were also higher in the protein group
– There was no difference in estimated glomerular filtration rate at 18 months
CONCLUSION
– Protein above recommended dietary allowance (0.8 g/kg) may preserve fat-free mass without adversely affecting skeletal health or renal function in healthy older adults


DOES PROTEIN CAUSES BONE LOSS – 2015


Stu Phillips
SUMMARY:
1. The basic observation that leads to this claim is that higher protein intake, particularly sources of protein rich sulphur-containing amino acids (meat and grains), leads to acidification of the blood and that causes resorption (the process or action by which something is reabsorbed) of calcium from bones, which leads to higher blood calcium, which leads to calciuria (more calcium being excreted in the urine). This is a very simplistic explanation, but it works for what I’m about to talk about.
2. Dr. Tanis Fenton, 2008 (http://www.ncbi.nlm.nih.gov/pubmed/18842807) “Evidence suggests a linear association between changes in calcium excretion in response to experimental changes in net acid excretion. However, this finding is not evidence that the source of the excreted calcium is bone or that this calciuria contributes to the development of osteoporosis.”
3. Dr. Jane Kerstetter at Yale showed that in highly detailed studies actually tracing calcium uptake and excretion that with increasing protein intake there was greater gut calcium uptake (http://www.ncbi.nlm.nih.gov/pubmed/15546911) and “The high-protein diet caused a significant reduction in the fraction of urinary calcium of bone origin and a nonsignificant trend toward a reduction in the rate of bone turnover. There were no protein-induced effects on net bone balance. These data directly demonstrate that, at least in the short term, high-protein diets are not detrimental to bone.” So onto further EBM to answer the question.
4. In another meta-analysis (http://www.ncbi.nlm.nih.gov/pubmed/19419322) the conclusion was that, “The acid-ash hypothesis posits that protein and grain foods, with a low potassium intake, produce a diet acid load, net acid excretion (NAE), increased urine calcium, and release of calcium from the skeleton, leading to osteoporosis… There is no evidence from superior quality balance studies that increasing the diet acid load promotes skeletal bone mineral loss or osteoporosis. Changes of urine calcium do not accurately represent calcium balance. Promotion of the “alkaline diet” to prevent calcium loss is not justified.”
5. Essentially, there are more meta-analyses on this topic (http://www.ncbi.nlm.nih.gov/pubmed/19754972, http://www.ncbi.nlm.nih.gov/pubmed/20459740), but all have reached the same conclusion, “A causal association between dietary acid load and osteoporotic bone disease is not supported by evidence and there is no evidence that an alkaline diet is protective of bone health.” In fact, some evidence (not conclusive) suggests that “Dietary protein is beneficial to bone health under conditions of adequate calcium intake…” (http://www.ncbi.nlm.nih.gov/pubmed/24316688).
6. There’s nothing like hyperbole and pseudo-science and the occasional ‘cherry-picked’ study to support the protein = bone loss argument, but it’s not evidence-based and it’s CERTAINLY not supported by science.


ASSOCIATIONS OF PROTEIN INTAKE AND PROTEIN SOURCE WITH BONE MINERAL DENSITY AND FRACTURE RISK – 2015


L Langsetmo, S I Barr, C Berger, N Kreiger, E Rahme, J D Adachi, A Papaioannou, S M Kaiser, J C Prior, D A Hanley, C S Kovacs, R G Josse, D Goltzman
INTRODUCTION:
High dietary protein has been hypothesized to cause lower bone mineral density (BMD) and greater fracture risk
OBJECTIVE:
Determine associations between total PRO intake, and PRO intake by source (dairy, non-dairy animal, plant) with BMD, BMD change, and incident osteoporotic fracture
RESULTS:
(1) Intakes of dairy protein (with adjustment for BMI) were positively associated with total hip BMD among men and women aged 50+ y, and in men aged 25-49.
(2) Among adults aged 50+ y, those with protein intakes of <12% TEI (women) and <11% TEI (men) had increased fracture risk compared to those with intakes of 15% TEI.
(3) Fracture risk did not significantly change as intake increased above 15% TEI, and was not significantly associated with protein source.
CONCLUSIONS:
(1) In contrast to hypothesized risk of high protein, we found that for adults 50+ y, low protein intake (below 15% TEI) may lead to increased fracture risk
(2) Source of protein was a determinant of BMD, but not fracture risk.


THE EFFECT OF WHEY PROTEIN ON BONE MASS IN OLDER ADULTS – 2015


Kerstetter JE1, Insogna KL. et al
CONTEXT
(1) It’s been assumed the increase in urine calcium (UCa) that accompanies an increase in protein was due to increased bone resorption (breakdown)
(2) However, studies using stable Ca isotopes have found that protein increases Ca absorption without increasing bone resorption
PARTICIPANTS
– 208 older women and men with a self-reported protein intake between 0.6 and 1.0 g/kg
INTERVENTION
– Subjects were asked to incorporate either a 45 g whey protein or isocaloric maltodextrin supplement into their usual diet for 18 months
RESULTS
(1) There were no significant differences between groups for changes in L-spine BMD (primary outcome) or the other skeletal sites of interest.
(2) Truncal lean mass was significantly higher in the protein group at 18 months.
(3) CTX, insulin-like growth factor-1 (IGF-1) and urinary urea were also higher in the protein group at the end of the study period.
(4) There was no difference in eGFR at 18 months.
CONCLUSION:
– PRO supplementation above RDA (0.8 g/kg) may preserve fat-free mass w/o adversely affecting skeletal or renal function in healthy older adults


 

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