1098
LETTERS TO THE EDITOR
The authors did not declare any conflicts of interest.
Adam M Bernstein Mladen Golubic Michael F Roizen From the Wellness Institute, Cleveland Clinic, Lyndhurst, OH (e-mail: [email protected]).
REFERENCES 1. Verreijen AM, Verlaan S, Engberink MF, Swinkels S, de Vogel–van den Bosch J, Weijs PJM. A high whey protein–, leucine-, and vitamin D–enriched supplement preserves muscle mass during intentional weight loss in obese older adults: a double-blind randomized controlled trial. Am J Clin Nutr 2015;101:279–86.
2. Food and Nutrition Board of the Institute of Medicine. Dietary Reference Intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. Washington (DC); National Academies Press; 2005. 3. Garlick PJ, McNurlan MA, Bark T, Lang CH, Gelato MC. Hormonal regulation of protein metabolism in relation to nutrition and disease. J Nutr 1998;128:356S–9S. 4. Pollak MN, Schernhammer ES, Hankinson SE. Insulin-like growth factors and neoplasia. Nat Rev Cancer 2004;4:505–18 10.1038/nrc1387. 5. Quinn KA, Treston AM, Unsworth EJ, Miller MJ, Vos M, Grimley C, Battey J, Mulshine JL, Cuttitta F. Insulin-like growth factor expression in human cancer cell lines. J Biol Chem 1996;271:11477–83. 6. Melnik BC. Leucine signaling in the pathogenesis of type 2 diabetes and obesity. World J Diabetes 2012;3:38–53. 7. Nakagawa S, Lagisz M, Hector KL, Spencer HG. Comparative and meta-analytic insights into life extension via dietary restriction. Aging Cell 2012;11:401–9. 8. Wang X, Proud CG. Nutrient control of TORC1, a cell-cycle regulator. Trends Cell Biol 2009;19:260–7. 9. Koeth RA, Wang Z, Levison BS, Buffa JA, Org E, Sheehy BT, Britt EB, Fu X, Wu Y, Li L, et al. Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med 2013;19:576–85. 10. Wing RR, Phelan S. Long-term weight loss maintenance. Am J Clin Nutr 2005;82 Suppl:222S–5S. doi: 10.3945/ajcn.114.105189.
Reply to AM Bernstein et al. Dear Editor: We appreciate the interest by Bernstein et al. in our recent publication on the effects of whey, leucine, and vitamin D supplementation on the preservation of muscle mass during intentional weight loss (1). Bernstein et al. address their concerns regarding the use of animal origin–derived protein in the supplement and an increased daily exposure to leucine. In the nutritional supplement, we specifically used whey protein enriched with the free amino acid leucine, which has fast digestion and absorption characteristics and has been shown to stimulate muscle protein synthesis. We cannot answer the question of whether plant-derived protein and micronutrients compared with animal (dairy) protein sources would provide the same or more benefits to older obese individuals during weight loss. However, Hector et al. (2) recently showed whey protein to be superior in stimulating muscle protein synthesis compared with soy protein before and after a 14-d hypocaloric intervention study in obese middle-aged adults. Together, these observations support the rationale to use whey protein in a supplement that aims to preserve muscle mass during a hypocaloric diet. The supplement also contained several other micronutrients, and we acknowledge that some of these have been associated with a contribution to muscle function; this was therefore already addressed in our article’s Discussion (1). As Bernstein et al. pointed out, it is of interest to see how the consumption of the supplement increases the daily total intake of leucine and compares with reported dietary intakes. At present, we would like to stress that the intake of protein and/or leucine is well within the current international standards of protein intake [maximal 35% of energy of total diet intake (3)] and therefore not uncommon or considered excessive (Figure 1). On average, diets with high amounts of either animal or plant protein contributing to total protein intake have a similar leucine content of ;7.6% (4). In our study, in the control group we measured a dietary protein intake of ;0.85 g protein/kg body weight per day. This would result in a leucine intake of 6.1 g/d when calculating with the average weight (95 kg) of our subjects. During the hypocaloric diet, the leucine
Downloaded from ajcn.nutrition.org at NEW YORK UNIVERSITY BOBST LIBRARY on May 11, 2015
we are concerned by the choice of protein given to participants. In addition, we believe the composition of the protein supplement may call into question the authors’ conclusions about its singular effect. Verreijen et al. state that whey is a high-quality protein that enhances muscle protein synthesis to a greater degree than other protein sources, an effect likely attributed to the faster digestion and absorption of its essential amino acids, which include leucine (1). Leucine, the authors point out, is itself a powerful stimulator of muscle protein synthesis (2). Yet, the potency of leucine to stimulate muscle growth may be mediated by insulin-like growth factor I (IGF-I) (3), the promotion of which is linked to cancer development (4, 5), as well as with adipogenesis and diabetes (6). Protein restriction downregulates IGF-I and the mammalian target of rapamycin (mTOR). These effects seem to promote healthy cellular aging (7). Leucine, which is predominantly found in foods of animal origin such as meat, dairy, and eggs (2, 6), appears to be the most potent amino acid in stimulating mTOR (8). It would have been of interest to see how much leucine participants were consuming throughout the study by Verreijen et al. Leucine is an essential amino acid and, for adults, the Estimated Average Requirement is 34 mg/kg per day and the Recommended Daily Allowance (RDA) is 42 mg/kg per day, equal to ;3.23 g and 3.99 mg/d for the obese 95-kg participants in the study by Verreijen et al. (2). The 2.8 g leucine in the supplement given to participants would have provided 87% of the Estimated Average Requirement and 67% of the RDA, without accounting for dietary intake (the median population intake for women is 4.69 g/d and for men is 6.60 g/d) (2). Although no adverse health effects of high leucine intake have been observed in humans, studies are limited because most involve a single dose (2). Although leucine may be a better choice for supplements than those with carnitine or phosphatidylcholine (9), the potential for carcinogenesis with long-term intake of high amounts of leucine—given both the mechanistic models and animal evidence—is nevertheless a concern (2). Importantly, too, the authors’ protein supplement contained much more than whey protein, leucine, and vitamin D. Compared with the control supplement, it was higher in nutrients important to muscle function, including magnesium, iron, zinc, and calcium (with nearly 50% of the RDA of calcium). Thus, any benefit to muscle function observed in the intervention group may not be ascribed to the whey, leucine, or vitamin D combination alone. Whether the authors would provide their protein supplement to participants during a weight-maintenance phase is not discussed. However, the study raises the question of whether a dietary pattern approach that provides obese adults with foods rich in plant protein and micronutrients could achieve a similar impact on weight loss and muscle function, with equal or better potential for long-term maintenance (10), and without the risk of adverse health consequences.
LETTERS TO THE EDITOR
1099
In summary, the amount of protein and particularly leucine in the present study can be considered at the high end of the normal distribution of intake. The safest way to proceed is to grow older without becoming obese. AMV reported no conflicts of interest related to this study. JdV-vdB and SV are employed by Nutricia Research. Nutricia Research was not involved in onsite data collection, except for audits at the research center. PJMW received research grants from Nutricia Research, Utrecht, The Netherlands, and Baxter Healthcare USA.
intake would be 8.9 g leucine (6.1 1 2.8 g from supplement) and 11.7 g leucine on a training day (6.1 1 2 supplements) (Figure 1). This would correspond to leucine intakes in a protein diet containing 1.2 g or 1.6 g protein/kg body weight per day, respectively (Figure 1). To compare, the calculated leucine intake in the intervention group was below the median daily leucine intake of 10.3 g leucine/d (in a 95-kg subject) as reported in the United Kingdom (5), and for older adults the current recommended level of protein intake is 1.0–1.2 g/kg per day, or 1.2–1.5 g/kg per day when combined with a chronic condition (6). Together, this substantiates that the additional leucine intake due to the supplement is not supraphysiologic but within the range of reported intakes in dietary surveys and the current international recommendations. Acute studies have been conducted to define a maximum tolerable level of leucine consumption per day. In a recent study, Pencharz et al. (7) based their advice on the upper level of leucine intake on the maximum amount of leucine that could still be oxidized. They estimated on the basis of these acute studies that a dose ,550 mg leucine/kg body weight per day would pose no risk to health. This corresponds to a daily consumption of 52.3 g leucine when calculating with a 95-kg subject, which is much higher than the estimated leucine consumption over the day in our intervention study. A supplementation study during 6 mo with 3 times 2.5 g leucine/d in addition to the normal diet (;0.95 g protein/kg body weight per day) was conducted in older patients with type 2 diabetes (8). Leucine supplementation resulted in a modest increase of ;10% in fasted plasma leucine concentrations after 2–4 wk without a progressive increase at later time points. In this controlled study, no adverse effects of leucine were reported. Intakes of protein and leucine in our study were within the normal range (Figure 1); consequently, we did not anticipate elevated concentrations of insulin-like growth factor I (IGF-I) and mammalian target of rapamycin (mTOR) activation beyond normal physiologic levels. We agree, however, with Bernstein et al. that longer-term studies on relevant clinical outcome variables related to the risk of chronic disease should be considered as further proof of safety. High-protein diets (25% of energy intake) support weight maintenance (9). In the present study, we show that the specialized supplement provides the benefit of preserving muscle mass during weight loss in older obese individuals. Whether consuming the supplement would also support weight maintenance was not studied, but muscle preservation may also have long-lasting benefits during weight maintenance.
From the Department of Nutrition and Dietetics, School of Sports and Nutrition, Amsterdam University of Applied Sciences, Amsterdam, The Netherlands (AMV, e-mail: a. [email protected]; PJMW) and Nutricia Research, Utrecht, The Netherlands (JdV-vdB, SV).
REFERENCES 1. Verreijen AM, Verlaan S, Engberink MF, Swinkels S, de Vogel-van den Bosch J, Weijs PJM. A high whey protein–, leucine-, and vitamin D–enriched supplement preserves muscle mass during intentional weight loss in obese older adults: a double-blind randomized controlled trial. Am J Clin Nutr 2015;101:279–86. 2. Hector AJ, Marcotte GR, Churchward-Venne TA, Murphy CH, Breen L, von Allmen M, Baker SK, Philips SM. Whey protein supplementation preserves postprandial myofibrillar protein synthesis during short-term energy restriction in overweight and obese adults. J Nutr 2014;145:246–52. 3. Food and Nutrition Board of the Institute of Medicine. Dietary Reference Intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. Washington (DC): National Academies Press; 2005. 4. Elliott P, Stamler J, Dyer AR, Appel L, Dennis B, Kesteloot H, Ueshima H, Okayama A, Chan Q, Garside DB, et al. Association between protein intake and blood pressure: the INTERMAP Study. Arch Intern Med 2006;166:79–87. 5. Millward DJ. Knowledge gained from studies of leucine consumption in animals and humans. J Nutr 2012;142 Suppl:2212S–9S. 6. Deutz NE, Bauer JM, Barazzoni R, Biolo G, Boirie Y, Bosy-Westphal A, Cederholm T, Cruz-Jentoft A, Krznaric¸ Z, Nair KS, et al. Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group. Clin Nutr 2014;33:929–36. 7. Pencharz PB, Elango R, Ball RO. Determination of the tolerable upper intake level of leucine in adult men. J Nutr 2012;142 Suppl:2220S–4S. 8. Leenders M, Verdijk LB, van der Hoeven L, van Kranenburg J, Hartgens F, Wodzig WK, Saris WH, van Loon LJ. Prolonged leucine supplementation does not augment muscle mass or affect glycemic control in elderly type 2 diabetic men. J Nutr 2011;141:1070–6. 9. Aller EE, Larsen TM, Claus H, Lindroos AK, Kafatos A, Pfeiffer A, Martinez JA, Handjieva-Darlenska T, Kunesova M, Stender S, et al. Weight loss maintenance in overweight subjects on ad libitum diets with high or low protein content and glycemic index: the DIOGENES trial 12-month results. Int J Obes (Lond) 2014;38:1511–7. doi: 10.3945/ajcn.114.105916.
Regular physical activity: a little is good, but is it good enough? Dear Editor: Ekelund et al. (1) nicely showed that physical inactivity causes an approximate twofold increase in the numbers of deaths compared
Downloaded from ajcn.nutrition.org at NEW YORK UNIVERSITY BOBST LIBRARY on May 11, 2015
FIGURE 1 Leucine intake in grams per day for different amounts of protein and supplement intake compared with international standards for protein and leucine intakes. Leucine intake per day was calculated on the basis of a 95-kg subject. The supplement, control diet, control diet plus 1 supplement, and control diet plus 2 supplements (training day) are shown in the context of the EAR and RDA for leucine, the median leucine intake in the United Kingdom (5), and the safe level of leucine intake (7) as well as different levels of protein intake considered to be safe (3, 6). EAR, Estimated Average Requirement; RDA, Recommended Dietary Allowance.
Amely M Verreijen Johan de Vogel-van den Bosch Sjors Verlaan Peter JM Weijs
LETTERS TO THE EDITOR
The authors did not declare any conflicts of interest.
Adam M Bernstein Mladen Golubic Michael F Roizen From the Wellness Institute, Cleveland Clinic, Lyndhurst, OH (e-mail: [email protected]).
REFERENCES 1. Verreijen AM, Verlaan S, Engberink MF, Swinkels S, de Vogel–van den Bosch J, Weijs PJM. A high whey protein–, leucine-, and vitamin D–enriched supplement preserves muscle mass during intentional weight loss in obese older adults: a double-blind randomized controlled trial. Am J Clin Nutr 2015;101:279–86.
2. Food and Nutrition Board of the Institute of Medicine. Dietary Reference Intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. Washington (DC); National Academies Press; 2005. 3. Garlick PJ, McNurlan MA, Bark T, Lang CH, Gelato MC. Hormonal regulation of protein metabolism in relation to nutrition and disease. J Nutr 1998;128:356S–9S. 4. Pollak MN, Schernhammer ES, Hankinson SE. Insulin-like growth factors and neoplasia. Nat Rev Cancer 2004;4:505–18 10.1038/nrc1387. 5. Quinn KA, Treston AM, Unsworth EJ, Miller MJ, Vos M, Grimley C, Battey J, Mulshine JL, Cuttitta F. Insulin-like growth factor expression in human cancer cell lines. J Biol Chem 1996;271:11477–83. 6. Melnik BC. Leucine signaling in the pathogenesis of type 2 diabetes and obesity. World J Diabetes 2012;3:38–53. 7. Nakagawa S, Lagisz M, Hector KL, Spencer HG. Comparative and meta-analytic insights into life extension via dietary restriction. Aging Cell 2012;11:401–9. 8. Wang X, Proud CG. Nutrient control of TORC1, a cell-cycle regulator. Trends Cell Biol 2009;19:260–7. 9. Koeth RA, Wang Z, Levison BS, Buffa JA, Org E, Sheehy BT, Britt EB, Fu X, Wu Y, Li L, et al. Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med 2013;19:576–85. 10. Wing RR, Phelan S. Long-term weight loss maintenance. Am J Clin Nutr 2005;82 Suppl:222S–5S. doi: 10.3945/ajcn.114.105189.
Reply to AM Bernstein et al. Dear Editor: We appreciate the interest by Bernstein et al. in our recent publication on the effects of whey, leucine, and vitamin D supplementation on the preservation of muscle mass during intentional weight loss (1). Bernstein et al. address their concerns regarding the use of animal origin–derived protein in the supplement and an increased daily exposure to leucine. In the nutritional supplement, we specifically used whey protein enriched with the free amino acid leucine, which has fast digestion and absorption characteristics and has been shown to stimulate muscle protein synthesis. We cannot answer the question of whether plant-derived protein and micronutrients compared with animal (dairy) protein sources would provide the same or more benefits to older obese individuals during weight loss. However, Hector et al. (2) recently showed whey protein to be superior in stimulating muscle protein synthesis compared with soy protein before and after a 14-d hypocaloric intervention study in obese middle-aged adults. Together, these observations support the rationale to use whey protein in a supplement that aims to preserve muscle mass during a hypocaloric diet. The supplement also contained several other micronutrients, and we acknowledge that some of these have been associated with a contribution to muscle function; this was therefore already addressed in our article’s Discussion (1). As Bernstein et al. pointed out, it is of interest to see how the consumption of the supplement increases the daily total intake of leucine and compares with reported dietary intakes. At present, we would like to stress that the intake of protein and/or leucine is well within the current international standards of protein intake [maximal 35% of energy of total diet intake (3)] and therefore not uncommon or considered excessive (Figure 1). On average, diets with high amounts of either animal or plant protein contributing to total protein intake have a similar leucine content of ;7.6% (4). In our study, in the control group we measured a dietary protein intake of ;0.85 g protein/kg body weight per day. This would result in a leucine intake of 6.1 g/d when calculating with the average weight (95 kg) of our subjects. During the hypocaloric diet, the leucine
Downloaded from ajcn.nutrition.org at NEW YORK UNIVERSITY BOBST LIBRARY on May 11, 2015
we are concerned by the choice of protein given to participants. In addition, we believe the composition of the protein supplement may call into question the authors’ conclusions about its singular effect. Verreijen et al. state that whey is a high-quality protein that enhances muscle protein synthesis to a greater degree than other protein sources, an effect likely attributed to the faster digestion and absorption of its essential amino acids, which include leucine (1). Leucine, the authors point out, is itself a powerful stimulator of muscle protein synthesis (2). Yet, the potency of leucine to stimulate muscle growth may be mediated by insulin-like growth factor I (IGF-I) (3), the promotion of which is linked to cancer development (4, 5), as well as with adipogenesis and diabetes (6). Protein restriction downregulates IGF-I and the mammalian target of rapamycin (mTOR). These effects seem to promote healthy cellular aging (7). Leucine, which is predominantly found in foods of animal origin such as meat, dairy, and eggs (2, 6), appears to be the most potent amino acid in stimulating mTOR (8). It would have been of interest to see how much leucine participants were consuming throughout the study by Verreijen et al. Leucine is an essential amino acid and, for adults, the Estimated Average Requirement is 34 mg/kg per day and the Recommended Daily Allowance (RDA) is 42 mg/kg per day, equal to ;3.23 g and 3.99 mg/d for the obese 95-kg participants in the study by Verreijen et al. (2). The 2.8 g leucine in the supplement given to participants would have provided 87% of the Estimated Average Requirement and 67% of the RDA, without accounting for dietary intake (the median population intake for women is 4.69 g/d and for men is 6.60 g/d) (2). Although no adverse health effects of high leucine intake have been observed in humans, studies are limited because most involve a single dose (2). Although leucine may be a better choice for supplements than those with carnitine or phosphatidylcholine (9), the potential for carcinogenesis with long-term intake of high amounts of leucine—given both the mechanistic models and animal evidence—is nevertheless a concern (2). Importantly, too, the authors’ protein supplement contained much more than whey protein, leucine, and vitamin D. Compared with the control supplement, it was higher in nutrients important to muscle function, including magnesium, iron, zinc, and calcium (with nearly 50% of the RDA of calcium). Thus, any benefit to muscle function observed in the intervention group may not be ascribed to the whey, leucine, or vitamin D combination alone. Whether the authors would provide their protein supplement to participants during a weight-maintenance phase is not discussed. However, the study raises the question of whether a dietary pattern approach that provides obese adults with foods rich in plant protein and micronutrients could achieve a similar impact on weight loss and muscle function, with equal or better potential for long-term maintenance (10), and without the risk of adverse health consequences.
LETTERS TO THE EDITOR
1099
In summary, the amount of protein and particularly leucine in the present study can be considered at the high end of the normal distribution of intake. The safest way to proceed is to grow older without becoming obese. AMV reported no conflicts of interest related to this study. JdV-vdB and SV are employed by Nutricia Research. Nutricia Research was not involved in onsite data collection, except for audits at the research center. PJMW received research grants from Nutricia Research, Utrecht, The Netherlands, and Baxter Healthcare USA.
intake would be 8.9 g leucine (6.1 1 2.8 g from supplement) and 11.7 g leucine on a training day (6.1 1 2 supplements) (Figure 1). This would correspond to leucine intakes in a protein diet containing 1.2 g or 1.6 g protein/kg body weight per day, respectively (Figure 1). To compare, the calculated leucine intake in the intervention group was below the median daily leucine intake of 10.3 g leucine/d (in a 95-kg subject) as reported in the United Kingdom (5), and for older adults the current recommended level of protein intake is 1.0–1.2 g/kg per day, or 1.2–1.5 g/kg per day when combined with a chronic condition (6). Together, this substantiates that the additional leucine intake due to the supplement is not supraphysiologic but within the range of reported intakes in dietary surveys and the current international recommendations. Acute studies have been conducted to define a maximum tolerable level of leucine consumption per day. In a recent study, Pencharz et al. (7) based their advice on the upper level of leucine intake on the maximum amount of leucine that could still be oxidized. They estimated on the basis of these acute studies that a dose ,550 mg leucine/kg body weight per day would pose no risk to health. This corresponds to a daily consumption of 52.3 g leucine when calculating with a 95-kg subject, which is much higher than the estimated leucine consumption over the day in our intervention study. A supplementation study during 6 mo with 3 times 2.5 g leucine/d in addition to the normal diet (;0.95 g protein/kg body weight per day) was conducted in older patients with type 2 diabetes (8). Leucine supplementation resulted in a modest increase of ;10% in fasted plasma leucine concentrations after 2–4 wk without a progressive increase at later time points. In this controlled study, no adverse effects of leucine were reported. Intakes of protein and leucine in our study were within the normal range (Figure 1); consequently, we did not anticipate elevated concentrations of insulin-like growth factor I (IGF-I) and mammalian target of rapamycin (mTOR) activation beyond normal physiologic levels. We agree, however, with Bernstein et al. that longer-term studies on relevant clinical outcome variables related to the risk of chronic disease should be considered as further proof of safety. High-protein diets (25% of energy intake) support weight maintenance (9). In the present study, we show that the specialized supplement provides the benefit of preserving muscle mass during weight loss in older obese individuals. Whether consuming the supplement would also support weight maintenance was not studied, but muscle preservation may also have long-lasting benefits during weight maintenance.
From the Department of Nutrition and Dietetics, School of Sports and Nutrition, Amsterdam University of Applied Sciences, Amsterdam, The Netherlands (AMV, e-mail: a. [email protected]; PJMW) and Nutricia Research, Utrecht, The Netherlands (JdV-vdB, SV).
REFERENCES 1. Verreijen AM, Verlaan S, Engberink MF, Swinkels S, de Vogel-van den Bosch J, Weijs PJM. A high whey protein–, leucine-, and vitamin D–enriched supplement preserves muscle mass during intentional weight loss in obese older adults: a double-blind randomized controlled trial. Am J Clin Nutr 2015;101:279–86. 2. Hector AJ, Marcotte GR, Churchward-Venne TA, Murphy CH, Breen L, von Allmen M, Baker SK, Philips SM. Whey protein supplementation preserves postprandial myofibrillar protein synthesis during short-term energy restriction in overweight and obese adults. J Nutr 2014;145:246–52. 3. Food and Nutrition Board of the Institute of Medicine. Dietary Reference Intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. Washington (DC): National Academies Press; 2005. 4. Elliott P, Stamler J, Dyer AR, Appel L, Dennis B, Kesteloot H, Ueshima H, Okayama A, Chan Q, Garside DB, et al. Association between protein intake and blood pressure: the INTERMAP Study. Arch Intern Med 2006;166:79–87. 5. Millward DJ. Knowledge gained from studies of leucine consumption in animals and humans. J Nutr 2012;142 Suppl:2212S–9S. 6. Deutz NE, Bauer JM, Barazzoni R, Biolo G, Boirie Y, Bosy-Westphal A, Cederholm T, Cruz-Jentoft A, Krznaric¸ Z, Nair KS, et al. Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group. Clin Nutr 2014;33:929–36. 7. Pencharz PB, Elango R, Ball RO. Determination of the tolerable upper intake level of leucine in adult men. J Nutr 2012;142 Suppl:2220S–4S. 8. Leenders M, Verdijk LB, van der Hoeven L, van Kranenburg J, Hartgens F, Wodzig WK, Saris WH, van Loon LJ. Prolonged leucine supplementation does not augment muscle mass or affect glycemic control in elderly type 2 diabetic men. J Nutr 2011;141:1070–6. 9. Aller EE, Larsen TM, Claus H, Lindroos AK, Kafatos A, Pfeiffer A, Martinez JA, Handjieva-Darlenska T, Kunesova M, Stender S, et al. Weight loss maintenance in overweight subjects on ad libitum diets with high or low protein content and glycemic index: the DIOGENES trial 12-month results. Int J Obes (Lond) 2014;38:1511–7. doi: 10.3945/ajcn.114.105916.
Regular physical activity: a little is good, but is it good enough? Dear Editor: Ekelund et al. (1) nicely showed that physical inactivity causes an approximate twofold increase in the numbers of deaths compared
Downloaded from ajcn.nutrition.org at NEW YORK UNIVERSITY BOBST LIBRARY on May 11, 2015
FIGURE 1 Leucine intake in grams per day for different amounts of protein and supplement intake compared with international standards for protein and leucine intakes. Leucine intake per day was calculated on the basis of a 95-kg subject. The supplement, control diet, control diet plus 1 supplement, and control diet plus 2 supplements (training day) are shown in the context of the EAR and RDA for leucine, the median leucine intake in the United Kingdom (5), and the safe level of leucine intake (7) as well as different levels of protein intake considered to be safe (3, 6). EAR, Estimated Average Requirement; RDA, Recommended Dietary Allowance.
Amely M Verreijen Johan de Vogel-van den Bosch Sjors Verlaan Peter JM Weijs
