Table 1.
Percentile cutoffs for average daily intake for nutritional factors among control mothers who participated in the National Birth Defects Prevention Study, 1997-2011a
| Nutritional Factor | 10th Percentile | 90th Percentile |
|---|---|---|
| Diet quality indexb | 5.9 | 17.6 |
| Nutrient | ||
| Beta carotene, µg | 623.5 | 5526.5 |
| Calcium, mg | 407.1 | 1151.4 |
| Choline, mg | 206.4 | 399.2 |
| Folate, µg dietary folate equivalent | 253.0 | 776.6 |
| Iron, mg | 7.0 | 19.6 |
| Lycopene, µg | 0.3 | 8128.8 |
| Niacin, mg | 13.0 | 26.4 |
| Retinol, µg | 192.2 | 755.6 |
| Riboflavin, mg | 1.2 | 2.6 |
| Thiamin, mg | 0.8 | 1.6 |
| Vitamin A, µg retinol activity equivalent | 358.2 | 1119.1 |
| Vitamin C, mg | 41.5 | 189.4 |
| No. of servings per day | ||
| Fruits | 0.6 | 3.8 |
| Vegetables | 0.8 | 3.6 |
| Dairy | 0.3 | 3.6 |
| Grains | 1.0 | 4.0 |
| Sweets | 0.3 | 3.3 |
| Dietary glycemic indexc | 46.2 | 58.3 |
| Percentage of calories from… | ||
| Protein | 13.2 | 23.0 |
| Fat | 21.0 | 37.1 |
| Saturated fat | 7.5 | 14.8 |
a Data source: Yoon et al.14 Nutritional factors were standardized to the median energy intake among all 11 109 study participants (1461.32 kcal/d) before determining percentile cutoffs. Values are from food frequency questionnaire data and therefore should be interpreted as semiquantitative and not as absolutes.
b A summary score of 6 positively scored components (grains, vegetables, fruits, folate, iron, and calcium) and 2 negatively scored components (intake of sweets and percentage of calories from fat). For each participant, we scored each component from 0 to 3 on the basis of quartiles of the distribution among controls, and then we summed the component scores to obtain the final value for the diet quality index; the score could range from 0 to 18, and a higher score indicates better diet quality. Index is based on a previously validated index17,18 adapted to the National Birth Defects Prevention Study food frequency questionnaire.19
c Calculated by summing the glycemic index of each food, multiplied by average daily servings and carbohydrate content of each food, and dividing the sum by total average daily carbohydrate intake; the glycemic index reflects the quality of dietary carbohydrate intake, relative to the blood glucose response to consumption of a food item.