TABLE 3.

Association between protein intake and quadriceps strength in men and women from the Framingham Offspring Cohort¹

	Quartiles of protein intake
	Quartile 1	Quartile 2	Quartile 3	Quartile 4	P-trend
Men, n	361	303	252	244
Total protein (median intake), g/d	64.2	70.2	78.9	101.6
Total protein	21.9 ± 0.3	22.2 ± 0.4	22.9 ± 0.4	22.6 ± 0.4	0.08
Animal protein2	22.3 ± 0.4	21.8 ± 0.4	22.8 ± 0.4	22.6 ± 0.4	0.30
Plant protein2	21.7 ± 0.3	22.1 ± 0.4	22.9 ± 0.4	22.9 ± 0.4	0.01
Women, n	297	352	425	422
Total protein (median intake), g/d	56.9	63.1	73.4	93.6
Total protein	18.0 ± 0.3	18.1 ± 0.3	18.8 ± 0.3	18.5 ± 0.3	0.10
Animal protein2	18.3 ± 0.3a,b	17.7 ± 0.3a	18.8 ± 0.3b	18.4 ± 0.3a,b	0.30
Plant protein2	18.2 ± 0.3a,b	17.9 ± 0.3a	18.3 ± 0.3a,b	19.0 ± 0.3b	0.01

¹Values are least squares means ± SEs unless otherwise indicated. Total n = 1160 men and 1496 women. The primary predictor was energy-adjusted residuals added to a constant, in which the constant equals the protein intake for the mean energy intake of the study population. Least squares means were adjusted for age, height, BMI, energy intake, physical activity, health status, and women’s menopause status. Adjustment for multiple comparisons was conducted with the use of Tukey’s test. Labeled means in a row without a common letter differ, P < 0.05. P-trend considered significant when <0.05 and considered marginally significant when <0.1.

²Animal protein intake and plant protein intake were adjusted for each other in the same model.