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Table 1 Number of selected items and the cumulative contribution to total nutrient intake from selected food items

From: Development and validation of a food frequency questionnaire for Japanese athletes (FFQJA)

  Number of items contributing up to 90% cumulative contribution* Stepwise multiple regression analysis
Number of items explaining more than 90% of variance*2 Cumulative R2 for
66 items*3
Cumulative R2 for
62 items*4
Energy 36 12 0.990 0.980
Protein 29 12 0.995 0.955
Fat 22 11 0.988 0.982
Carbohydrate 29 9 0.990 0.980
Calcium (Ca) 34 16 0.992 0.943
Iron (Fe) 39 19 0.979 0.867
Retinol*5 17 3 0.999 0.998
Vitamin B1 28 3 0.998 0.450
Vitamin B2 30 6 0.991 0.665
Vitamin C 16 3 0.999 0.942
Dietary fiber 27 16 0.975 0.849
  1. *Number of food items to reach cumulative percentage contribution of 90% from 103 foods/food groups
  2. *2 Number of food items selected by stepwise multiple regression analysis explaining more than 90% of variance from 103 foods/food groups
  3. *3 66 items were all foods/food groups selected by contribution to 90% cumulative contribution and multiple regression analysis, excluding sugar, sauces, soy sauce, stock, and other seasonings (sweet sake, ketchup, and spices), and including nuts, honey or maple syrup, bread stuffed with meat or vegetables, sponge cake or steamed bread, rice crackers, chips, and alcoholic drinks
  4. *4 62 items were only basic items asked about in the food frequency questionnaire. Supplements, minor cereals, sesame, and soymilk were excluded from the list of 66 items
  5. *5 Retinol was calculated as retinol activity equivalents