In older people with osteoporosis , higher protein intake ( ≥ 0.8-g/kg body weight/day , i.e. , above the current RDA ) is associated with higher BMD , a slower rate of bone loss , and reduced risk of hip fracture , provided that dietary calcium intakes are adequate .
Intervention with dietary protein supplements attenuate age-related BMD decrease and reduce bone turnover marker levels , together with an increase in IGF-I and a decrease in PTH .
There is no evidence that diet-derived acid load is deleterious for bone health .
Thus , insufficient dietary protein intakes may be a more severe problem than protein excess in the elderly .
A summary of systematic review s and meta-analyses addressing the benefits and risks of dietary protein intakes  for  bone health in adults suggests that dietary protein levels even above the current RDA may be beneficial in reducing bone loss and hip fracture risk , provided calcium intakes are adequate .
Several systematic review s and meta-analyses have addressed the benefits and risks of dietary protein intakes for bone health in adults .
Adequate supplies of dietary protein are required for optimal bone growth and maintenance of healthy bone .
Variation in protein intakes within the “ normal ” range accounts for 2–4 % of BMD variance in adults .
Low iron status as a factor of increased bone resorption and effects of an iron and vitamin D-fortified skimmed milk on bone remodelling in young Spanish women
Purpose This study aim ed to determine whether there is a relationship between iron status and bone metabolism , and to compare the effects of the consumption , as part of the usual diet , of an iron or iron and vitamin D-fortified skimmed milk on bone remodelling in iron-deficient women . Methods Young healthy iron-deficient or iron-sufficient women ( serum ferritin ≤30 ng/mL or > 30 ng/mL , respectively ) were recruited . Iron-deficient women were assigned to a nutritional intervention consisting of a r and omised , controlled , double-blind , parallel design trial of 16 weeks during winter . They consumed , as part of their usual diet , an iron ( Fe group , n = 54 ) or iron and vitamin D-fortified ( Fe+D group , n = 55 ) flavoured skimmed milk ( iron , 15 mg/day ; vitamin D3 , 5 μg/day , 200 IU ) . The iron-sufficient women followed their usual diet without supplementation ( R group , n = 56 ) . Dietary intake , body weight , iron biomarkers , 25-hydroxyvitamin D ( 25OHD ) , parathyroid hormone ( PTH ) , procollagen-type 1 N-terminal propeptide ( P1NP ) , and aminoterminal telopeptide of collagen I ( NTx ) were determined . Results Negative correlations were found between baseline log-ferritin and log-NTx ( p < 0.001 ) , and between transferrin and P1NP ( p = 0.002 ) . Serum 25OHD increased ( from 62 ± 21 to 71 ± 21 nmol/L , mean ± SD , p < 0.001 ) while P1NP and NTx decreased in Fe+D during the assay ( p = 0.004 and p < 0.001 , respectively ) . NTx was lower in Fe+D compared to Fe at week 8 ( p < 0.05 ) and was higher in Fe and Fe+D compared to R throughout the assay ( p < 0.01 ) . PTH did not show changes . Conclusions Iron deficiency is related with higher bone resorption in young women . Consumption of a dairy product that supplies 5 μg/day of vitamin D3 reduces bone turnover and increases circulating 25OHD to nearly reach an optimal vitamin D status , defined as 25OHD over 75
In older people with osteoporosis , higher protein intake ( ≥ 0.8-g/kg body weight/day , i.e. , above the current RDA ) is associated with higher BMD , a slower rate of bone loss , and reduced risk of hip fracture , provided that dietary calcium intakes are adequate .
Intervention with dietary protein supplements attenuate age-related BMD decrease and reduce bone turnover marker levels , together with an increase in IGF-I and a decrease in PTH .
There is no evidence that diet-derived acid load is deleterious for bone health .
Thus , insufficient dietary protein intakes may be a more severe problem than protein excess in the elderly .
A summary of systematic review s and meta-analyses addressing the benefits and risks of dietary protein intakes  for  bone health in adults suggests that dietary protein levels even above the current RDA may be beneficial in reducing bone loss and hip fracture risk , provided calcium intakes are adequate .
Several systematic review s and meta-analyses have addressed the benefits and risks of dietary protein intakes for bone health in adults .
Adequate supplies of dietary protein are required for optimal bone growth and maintenance of healthy bone .
Variation in protein intakes within the “ normal ” range accounts for 2–4 % of BMD variance in adults .