Table 4.

Amino acid groups and non-dietary correlates for skeletal muscle mass index.

Variables	β-Coefficient	p
Sex, men	6.99	<0.001
Age (years)	−0.05	<0.001
Education level
High school graduation or higher	−0.19	0.12
Body mass index (kg/m2)	−0.41	<0.001
Smoking status
Smoker	−0.20	0.16
Household income
High	0.06	0.77
Mid-high	0.15	0.42
Mid-low	0.08	0.62
Physical activity level (METs-h/week) 1
High	0.58	<0.001
Middle	0.77	0.003
Alcohol consumption (yes)	0.07	0.55
Energy intake (kcal/day)	0.0005	<0.001
Essential amino acid intake (g/day) 2	−0.04	0.59
Non-essential amino acid intake (g/day) 3	0.03	0.68
Branched-chain amino acid intake (g/day) 4	0.31	0.01
Aromatic amino acid intake (g/day) 5	−0.24	0.37
Polar amino acid intake (g/day) 6	0.01	0.88
Non-polar amino acid intake (g/day) 7	−0.10	0.23

Multivariable-adjusted findings including each of the presented variables. ¹ Physical activity was categorized into three groups, according to tertile of metabolic equivalents (MET)-hours/week. ² Essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. ³ Non-essential amino acids: alanine, arginine, aspartate, cysteine, glutamate, glycine, proline, serine, taurine, and tyrosine. ⁴ Branched-chain amino acids: isoleucine, leucine, and valine. ⁵ Aromatic amino acids: phenylalanine, tryptophan, and tyrosine. ⁶ Polar amino acids: cysteine, glutamate, serine, threonine, and tyrosine. ⁷ Non-polar amino acids: alanine, glycine, isoleucine, leucine, methionine, phenylalanine, proline, tryptophan, and valine.