Adverse gastrointestinal events were more common with high-protein diets .
Multivariable meta-regression analysis showed no significant dose response with higher protein intake .
Conclusions : Higher-protein diets  probably improve adiposity , blood pressure and triglyceride levels , but these effects are small and need to be weighed against the potential for harms
Background / Objectives : Numerous r and omised controlled trials ( RCTs ) published in first tier medical journals have evaluated the health effects of diets high in protein .
We conducted a rigorous systematic review of RCTs comparing higher- and lower-protein diets .
Effect of high vegetable protein diets on urinary calcium loss in middle-aged men and women
Objective : To determine the effect of high-protein diets , which have recently been promoted for their health benefits , on urinary calcium losses and bone turnover in older subjects . Design : R and omized controlled cross-over study . Setting : Teaching hospital and university . Subjects : Twenty hyperlipidemic men and postmenopausal women ( age 56±2 y ) completed the study . Interventions : One-month test and control phases during which subjects consumed equi-energy metabolic diets high in calcium ( 1578 and 1593 mg/day , respectively ) . On the test diet 11 % of total dietary energy from starch in the control bread was replaced by protein ( wheat gluten ) , result ing in 27 % of energy from protein on the test diet vs 16 % on the control diet . Main outcome measure : Urinary calcium excretion . Results : Compared with the control diet , at week 4 , the test diet increased mean ( ±s.e.m . ) 24 h urinary output of calcium ( 139±15 vs 227±21 mg , P=0.004 ) . The treatment difference in urinary calcium loss correlated with the serum anion gap as a marker of metabolic acid production ( r=0.57 , P=0.011 ) . Serum calcium levels were marginally lower 2.41±0.02 vs 2.38±0.02 mmol/l ( P=0.075 ) , but there was no significant treatment difference in calcium balance , possibly related to the high background calcium intake on both diets . Conclusions : In the presence of high dietary calcium intakes the vegetable protein gluten does not appear to have a negative effect on calcium balance despite increased urinary calcium loss . Sponsorship : The University-Industry Research Partnership Program of the Natural Sciences and Engineering Research Council of Canada , Loblaw Br and s Limited , Toronto , ON , and Kraft Canada Inc. Don Mills , ON . DJAJ is funded as a Canada Research Chair in Metabolism and Nutrition at the University of Toronto by the Federal Government of Canada , Ottawa
Adverse gastrointestinal events were more common with high-protein diets .
Multivariable meta-regression analysis showed no significant dose response with higher protein intake .
Conclusions : Higher-protein diets  probably improve adiposity , blood pressure and triglyceride levels , but these effects are small and need to be weighed against the potential for harms
Background / Objectives : Numerous r and omised controlled trials ( RCTs ) published in first tier medical journals have evaluated the health effects of diets high in protein .
We conducted a rigorous systematic review of RCTs comparing higher- and lower-protein diets .