Table 4.

Beta values and ΔR² of multiple linear regression using perceived stress (PSS), depressive (BDI) or loneliness symptoms (UCLA) to predict S-IgA/SC, IgA1/SC and IgA2/SC

PSS Model		S-IgA/SC			IgA1/SC			IgA2/SC
		β	t	ΔR2	β	t	ΔR2	β	t	ΔR2
Model 1	Gender	−0.05	−1.54	0.03	−0.04	−1.45*	0.06	0.03	−1.18**	0.09
	Age	0.00	−0.17		0.005	1.28		0.01	2.88**
Model 2	Smoking	−0.04	−1.05	0.01	−0.03	−0.97	0.01	0.01	0.23	0.01
	Alcohol	0.008	0.22		0.01	0.44		0.03	0.85
	Caffeine	−0.01	−0.40		−0.01	0.40		−0.03	−0.85
Model 3	Protein	−0.00	0.84	0.007	−0.00	0.25	0.01	−0.00	−0.59	0.003
Model 4	PSS	−0.003	−1.61	0.02	−0.003	−2.10*	0.04	−0.001	−0.67	0.004
BDI Model		S-IgA/SC			IgA1/SC			IgA2/SC
		β	t	ΔR2	β	t	ΔR2	β	t	ΔR2
Model 1	Gender	−0.06	−1.69	0.03	−0.04	−1.64*	0.06	−0.03	−1.11**	0.09
	Age	0.00	−0.17		−0.05	1.30		0.01	2.83**
Model 2	Smoking	−0.04	−0.89	0.01	−0.02	−0.75	0.01	0.02	0.45	0.01
	Alcohol	0.01	0.35		0.02	0.61		0.03	1.11
	Caffeine	−0.01	−0.31		−0.01	−0.27		−0.02	−0.71
Model 3	Protein	0.00	1.25	0.007	0.00	0.80	0.001	−0.00	−0.16	0.003
Model 4	BDI	−0.01	−1.83	0.03	−0.01	−2.42*	0.05	−0.01	−2.05*	0.04
UCLA Model		S-IgA/SC			IgA1/SC			IgA2/SC
		β	t	ΔR2	β	t	ΔR2	β	t	ΔR2
Model 1	Gender	−0.07	−2.22	0.03	−0.06	−2.43	0.06	−0.05	−1.60**	0.09
	Age	−0.002	−0.28		0.005	1.09		0.01	2.74**
Model 2	Smoking	−0.05	−1.20	0.01	−0.04	−1.20	0.01	0.004	0.13	0.01
	Alcohol	0.00	−0.01		0.003	0.13		0.02	0.74
	Caffeine	−0.001	−0.20		−0.002	−0.08		−0.02	−0.66
Model 3	Protein	−0.00	0.98	0.007	0.00	0.44	0.001	−0.00	−0.51	0.003
Model 4	UCLA	−0.003	−1.77	0.03	−0.003	−2.69**	0.06	−0.002	−1.41	0.02

^*p<.05;

^**p<.01

IgA1: Immunoglobulin A subclass 1; IgA2: Immunoglobulin A subclass 2; S-IgA: Secretory Immunoglobulin A; SC: Secretory Component; BDI: Beck Depression Inventory; PSS: Perceived Stress Scale; UCLA: University of California at Los Angeles Loneliness Scale.