Table 5.

Relationship between selected food intakes in primary school children and nutrition knowledge of the children and their guardians by linear regression analysis.^a

Food intake, g/1000 kcal	Independent variables in regression modelsb	Model 1		Model 2		Model 3
		Regression coefficient	P valuec	Regression coefficient	P valuec	Regression coefficient	P valuec
Staple foodsd	Children's knowledgee	−0.16	0.53	−0.24	0.77	−0.17	0.5
	Guardians' knowledgef	−0.65	0.033*	−0.65	0.034*	1.76	0.06
	Children's sexg	−7.62	0.26	−11.2	0.76	107.5	0.012*
	Grade	−0.82	0.69	−0.83	0.69	−0.72	0.72
	Guardians' incomeh	−3.18	0.42	−3.18	0.43	−3.83	0.33
	Children's knowledge ∗ Children's sex			0.05	0.92
	Guardians' knowledge ∗ Children's sex					−1.6	0.0065*
Vegetable	Children's knowledgee	0.6	0.0025*	0.95	0.13	0.6	0.0024*
	Guardians' knowledgef	1	<0.0001*	0.99	<0.0001*	0.32	0.66
	Children's sexg	9.46	0.069	26	0.36	−22.9	0.49
	Grade	1.08	0.5	1.12	0.48	1.05	0.51
	Guardians' incomeh	1.16	0.71	1.16	0.71	1.35	0.66
	Children's knowledge ∗ Children's sex			−0.23	0.56
	Guardians' knowledge ∗ Children's sex					0.45	0.32
Fruit	Children's knowledgee	0.13	0.13	−0.24	0.39	0.14	0.12
	Guardians' knowledgef	0.06	0.57	0.06	0.54	−0.83	0.0092*
	Children's sexg	0.75	0.74	−16.7	0.19	−41.9	0.0042*
	Grade	−0.06	0.94	−0.1	0.89	−0.09	0.89
	Guardians' incomeh	2.4	0.079	2.4	0.079	2.63	0.052
	Children's knowledge ∗ Children's sex			0.24	0.16
	Guardians' knowledge ∗ Children's sex					0.59	0.0032*
Sweets and snacks	Children's knowledgee	−0.05	0.55	0.25	0.36	−0.05	0.57
	Guardians' knowledgef	−0.12	0.24	−0.13	0.23	−0.62	0.055
	Children's sexg	5	0.03*	19.3	0.13	−18.6	0.21
	Grade	0.31	0.66	0.35	0.62	0.29	0.68
	Guardians' incomeh	0.33	0.8	0.33	0.81	0.46	0.73
	Children's knowledge ∗ Children's sex			−0.2	0.25
	Guardians' knowledge ∗ Children's sex					0.33	0.1

^aAmong 316 analyzed guardians, 12 did not answer the question about household income, and the pairs of these guardians and their children were deleted from the analysis in Table 5.

^bLinear regression model was used to examine the relationship between children's food intake and nutrition knowledge of the children and their guardians. All models include food intake (continuous, g/kcal) as a dependent variable. Model 1: Independent variables were children's knowledge, guardians' knowledge, children's sex, grade, and guardians' income. Model 2: Independent variables were children's knowledge, guardians' knowledge, children's sex, grade, guardians' income, and an interaction term between children's knowledge and children's sex. Model 3: Independent variables were children's knowledge, guardians' knowledge, children's sex, grade, guardians' income, and an interaction term between guardians' knowledge and children's sex.

^cResults in tests for regression coefficients, “*” shows p < 0.05.

^dIntake of staple foods was sum of rice, bread, and noodle.

^eChildren's knowledge is the percentage of correct answers in nutrition knowledge questionnaire for children, and used as a continuous variable in the models.

^fGuardians' knowledge is the percentage of correct answers in nutrition knowledge questionnaire for adults, and used as a continuous variable in the models. The percentage of correct answers in the guardians was calculated after excluding the section about awareness of dietary recommendations.

^gChildren's sex was coded as below: boy = 1, girl = 2. The reference was the boy.

^hGuardians' income was categorized into four groups, and the lowest income group was set as the reference. Each income group was assigned a score: <3 million yen = 1, 3 to <6 million yen = 2, 6 to <9 million yen = 3, and ≥9 million yen = 4. Linear regression analysis was used to test trend of association.