A higher protein intake at breakfast and lunch is associated with a higher total daily protein intake in older adults: a post-hoc cross-sectional analysis of four randomised controlled trials.

BACKGROUND: A protein intake of 30-40 g per meal is suggested to maximally stimulate muscle protein synthesis in older adults and could therefore contribute to the prevention of sarcopenia. Protein intake at breakfast and lunch is often low and offers a great opportunity to improve daily protein intake. Protein, however, is known for its satiating effects. Therefore, we explored the association between the amount of protein intake at breakfast and lunch and total daily protein intake in older adults. METHODS: Protein intake was assessed by a 3-day food record in 498 community dwelling older adults (≥55 years) participating different lifestyle interventions. Linear mixed model analysis was used to examine the association between protein intake at breakfast or lunch and total daily protein intake, adjusted for sex, age, body mass index, smoking status, study and total energy intake. RESULTS: After adjustment for potential confounders, a 10 g higher protein intake at breakfast was associated with a 3.2 g higher total daily protein intake (P = 0.008) for males and a 4.9 g (P < 0.001) higher total daily protein intake for females. A 10 g higher protein intake at lunch was associated with a 3.7 g higher total daily protein intake (P < 0.001) for males, and a 5.8 g higher total daily protein intake (P < 0.001) for females. CONCLUSIONS: A higher protein intake at breakfast and lunch is associated with a higher total daily protein intake in community dwelling older adults. Stimulating a higher protein intake at breakfast and lunch might represent a promising nutritional strategy to optimise the amount of protein per meal without compromising total daily protein intake.

Effect of a high-protein diet on maintenance of blood pressure levels achieved after initial weight loss: the DiOGenes randomized study.

Randomized trials have shown significant blood pressure (BP) reductions after increased protein compared with carbohydrate intake, but the effect on BP maintenance after initial weight loss is unclear. We examined the effect of a high-protein diet on the maintenance of reduced BP after weight loss in 420 overweight adults from the Diet, Obesity and Genes study. After an 8-week weight-loss period (>8% BW), subjects (42±6 years) were randomized to either a high-protein diet (23-28 en% protein) or a lower-protein control diet (10-15 en% protein) for 26 weeks. BMI after weight loss was 30.3±4.3 kg m(-2), BP was 118/73 mm Hg and 28 subjects (6.5%) used antihypertensive agents. Systolic BP during 26 weeks of weight maintenance dietary intervention increased in both treatment groups, but it was 2.2 mm Hg less (95% CI: -4.6 to 0.2 mm Hg, P=0.08) in the high-protein group than in the lower-protein control group. In 191 (pre)hypertensive subjects (baseline systolic BP⩾120 mm Hg), a larger difference was observed (-4.2 mm Hg (-7.7, -0.7), P=0.02). The effect was attenuated after adjustment for initial BP (-3.4 mm Hg (-6.9, -0.03), P=0.048), and after additional adjustment for weight change (-2.7 mm Hg (-6.1, 0.4), P=0.11). Adjustment for 24-h urinary excretion of sodium and potassium did not change the results. Diastolic BP yielded similar results. These findings suggest that a BP reduction after weight loss is better maintained when the intake of protein is increased at the expense of carbohydrates. This effect is partly mediated by body weight.

Intake of total protein, plant protein and animal protein in relation to blood pressure: a meta-analysis of observational and intervention studies.

There is growing evidence from epidemiological studies that dietary protein may beneficially influence blood pressure (BP), but findings are inconclusive. We performed a meta-analysis of 29 observational studies and randomized controlled trials (RCTs) of dietary protein and types of protein in relation to BP or incident hypertension, published until January 2012. The analysis included eight cross-sectional studies (n=48 985), four prospective studies (n=11 761) and 17 RCTs (n=1449). A modest inverse association between total protein intake and BP (-0.20 mm Hg systolic (95% CI: -0.39, -0.01) per 25 g (∼1 s.d.)) was found in cross-sectional studies, but not in prospective studies (relative risk of 0.99 (95% CI: 0.96, 1.02)). For RCTs that used carbohydrate as a control treatment, the pooled BP effect was -2.11 mm Hg systolic (95% CI: -2.86, -1.37) for a weighed mean contrast in protein intake of 41 g per day. A non-significant inverse association of -0.52 mm Hg systolic (95% CI: -1.10, +0.05) per 11 g (∼1 s.d.) was found for plant protein in cross-sectional studies, whereas animal protein was not associated with BP. In prospective studies and RCTs, however, the associations of plant protein and animal protein with BP were broadly similar. These findings suggest that increasing the intake of protein at the expense of carbohydrates may have a beneficial effect on BP. The BP effect of specific types of protein remains to be established.

The effect of conjugated linoleic acid, a natural trans fat from milk and meat, on human blood pressure: results from a randomized crossover feeding study.

Cis-9, trans-11 conjugated linoleic acid (CLA) is a natural trans fatty acid that is largely restricted to ruminant fats and consumed in foods and supplements. Its role in blood pressure (BP) regulation is still unclear. We examined the effect of cis-9, trans-11 CLA on BP compared with oleic acid. A total of 61 healthy volunteers were sequentially fed each of 3 diets for 3 weeks, in random order, for a total of 9 weeks. The diets were identical except for 7% of energy (18.9 g in a diet of 10 MJ day(-1)) that was provided either by oleic acid, by industrial trans fatty acids or by cis-9, trans-11 CLA. We measured BP on two separate days at the end of each intervention period. At baseline, mean BP was 113.8±14.4 mm Hg systolic and 66.3±9.6 mm Hg diastolic. The effect of the CLA diet compared with the oleic acid diet was 0.11 mm Hg (95% confidence interval: -1.27, 1.49) systolic and -0.45 mm Hg (-1.63, 0.73) diastolic. After the industrial trans fatty acid diet, the effect was 1.13 mm Hg (-0.25, 2.51) systolic and -0.44 mm Hg (-1.62, 0.73) diastolic compared with the oleic acid diet. Our study suggests that short-term high intakes of cis-9,trans-11 CLA do not affect BP in healthy volunteers.