Table 6

Intraclass correlation coefficients for food frequency questionnaires completed at the beginning and end of 12 months

FFQ 1 vs. FFQ 2

Unadjusted

r (CI)

Energy adjusted

r (CI)


Total Energy (kcal)

0.87 (0.78, 0.92)

Total Carbohydrate

0.85 (0.76, 0.91)

0.76 (0.61, 0.85)

Protein

0.83 (0.73, 0.90)

0.79 (0.66, 0.87)

Total Fat

0.85 (0.75, 0.90)

0.74 (0.57, 0.84)

Total Saturated Fat

0.78 (0.65, 0.87)

0.50 (0.18, 0.69)

Total MUFA

0.82 (0.71, 0.89)

0.79 (0.66, 0.87)

Total PUFA

0.75 (0.60, 0.80)

0.54 (0.24, 0.71)

Linoleic acid

0.75 (0.59, 0.85)

0.68 (0.48, 0.80)

Linolenic acid

0.73 (0.55, 0.83)

0.55 (0.26, 0.72)

Cholesterol

0.80 (0.67, 0.87)

0.80 (0.67, 0.87)

Calcium

0.85 (0.75, 0.91)

0.79 (0.66, 0.87)

Iron

0.90 (0.84, 0.94)

0.68 (0.47, 0.80)

Retinol

0.73 (0.56, 0.83)

0.74 (0.57, 0.84)

Beta-carotene (ug)

0.71 (0.53, 0.82)

0.75 (0.59, 0.85)

Vitamin E

0.77 (0.56, 0.82)

0.78 (0.58, 0.85)

Folate

0.88 (0.80, 0.92)

0.77 (0.62, 0.86)

Vitamin K

0.72 (0.54, 0.83)

0.72 (0.54, 0.83)

Zinc

0.79 (0.65, 0.87)

0.79 (0.66, 0.87)

Total dietary fiber

0.82 (0.70, 0.90)

0.84 (0.68, 0.90)

Alcohol

0.76 (0.45, 0.89)

0.68 (0.27, 0.86)


a Energy-adjusted correlations between dietary methods as suggested by Willett (1)

b All variables were log-transformed before analysis.

Jackson et al. Nutrition Journal 2011 10:28   doi:10.1186/1475-2891-10-28

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