Validation of a Food Frequency Questionnaire to Assess Folate

Status among Georgia State University StudentsMiriam Abouelnasr, Carrie Asher, Erin Buehler,

Holly Cheek, Andrea Penix, Lauryn Whitfield

Why Folate?

Percentage of people with low folate has decreased since the early 90s with the United States’ fortification of grain products, but folate status is still low in some populations.

In 2000, 5.1% of US women of childbearing age were deficient in folate.

The Facts About Folate

Many dietary sources Leafy greens, cereals and grains Egg yolks and liver

Need about 400 μg folate/day Essential for

synthesis of DNA and RNA methylation of DNA conversion of homocysteine to methionine Erythrocyte synthesis

Population’s Problems Cooking foods such as grains and leafy

greens may reduce the amount of folate that is bioavailable.

In a study of collage aged women only ~1/3 took folic acid supplements.

Folate Deficiency Consequences About 1/ 1000 births in the US is complicated

by a NTD High levels of homocysteine are implicated in

cardiovascular disease Inadequate biosynthesis of DNA/RNA can

cause megaloblastic anemia

Materials and Methods Subjects

15 college age women (ages 18-30) 14 college age men (ages 18-30)

Location: Georgia State University campus

Purpose: To validate a food frequency questionnaire (FFQ) that is likely to

assess the intake of folate in the Georgia State University community

Two FFQ’s administered: 1. Gold Standard FFQ obtained from National Health and Nutrition

Examination Survey (NHANES) 2. Coordinated program FFQ (CPFFQ)

Gold Standard FFQ Administered first

Frequency of consumption of various folate-containing foods assessed for the past 12 months

Foods asked in each question: Oatmeal, grits or other cooked cereal Cold cereal Whole grain cereal such as shredded wheat, Wheaties, Cheerios, Raisin Bran or other

bran, oat, or whole wheat cereal Cooked greens such as spinach, turnip, collard, mustard, chard, or kale Raw greens such as spinach, turnip, collard, mustard, chard or kale Coleslaw Sauerkraut or cabbage (other than coleslaw) Carrots (fresh, canned, or frozen) String beans or green beans (fresh, canned or frozen) Corn (fresh, canned, or frozen) Broccoli (fresh or frozen) Cauliflower or Brussels sprouts (fresh or frozen)

Mixed vegetables Sweet or hot peppers (green, red, or yellow) Fresh tomatoes (including those in salads) Summer squash (include yellow or green squash) Lettuce salads (with or without other vegetables) Sweet potatoes or yams Tortillas or tacos Cooked dried beans (such as baked beans, pintos, kidney,

black-eyed peas, lima, lentils, soybeans, or refried beans) Rice or other cooked grains (such as bulgur, cracked wheat, or

millet) Pancakes, waffles, or French Toast Lasagna, stuffed shells, stuffed manicotti, ravioli, or tortellini Macaroni and cheese Pasta salad or macaroni salad Bagels or English muffins Breads or rolls as part of sandwiches (including burger and hot

dog rolls) Breads or dinner rolls not as part of sandwiches

Example of GSFFQNever

1-6 times per year

1 time per year

1 time per month

2-3 times per month

1 time per week

2 times per week

3-4 times per week

5-6 times per week

1 time per day

2 or more times per day

Coordinated Program FFQ Administered second

Frequency of consumption per week of various folate-containing foods

Foods asked in each question: Beans, lentils, and chickpeas/garbonzos (include

kidney, pinto, refried, black, and baked beans) Peanuts, peanut butter, or other types of nuts and seeds All-Bran, All-Bran Extra Fiber, 100% Bran, Fiber One, or Total Cereals Cereals such as corn flakes, cheerios, rice krispies, or presweetened

cereals Hot cereals such as oatmeal, cream of wheat, cream of rice, and grits White bread, rolls, bagels, biscuits, English muffins, or crackers Dark breads and rolls, including whole wheat, rye, and pumpernickel Corn bread, corn muffins, or corn tortillas Flour tortillas

Rice Salted snacks such as potato chips, taco chips, corn chips,

and salted pretzels and popcorn Vegetables Cooked greens such as mustard, turnip, or collard Okra or asparagus Broccoli or Brussel sprouts Corn Raw spinach Raw onions Multi-vitamins

Example of CPFFQ

0 1 2 3 4 5 More than 5

Analysis of Data The nutrient content of the CPFFQ and GSFFQ was analyzed using the

nutrient data base at MyPyramid.gov

The validity of the CPFFQ was determined by using standard statistical methodology such as: Sensitivity Specificity PPV NPV Accuracy Likelihood Ratio Odds Ratio Relative Risk Mean Standard Deviation Median 95% Confidence Interval

ResultsCPFFQ GSFFQ TOTAL

YES NO

YES 0 8 8

NO 1 20 21

TOTAL 1 28 29

Sensitivity= 0; the CPFFQ picks up 0% of people who don't meet the DRI for folate

Specificity= 0.285714; 29% of the time the CPFFQ correctly excludes people that do meet the DRI

PPV= 0; If a person meets the DRI according to the CPFFW there is a 0% chance that that he or she actually meets the DRI

NPV= 0.952381; If a person does not meet the DRI according to the CPFFQ there is a 95% chance that he or she does not meet the DRI

Accuracy= 0.689655; 69% of all tests have given the correct result

Likelihood ratio= 0 It is 0% likely that a positive test will be found in a person meeting the DRI, as compared to one not meeting the DRI

Association between the Surveys Relative Risk: 0, which is <1 so the likelihood

of people not meeting the DRI for folate occurred more in the GSFFQ.

Odds Ratio: 0, which is <1, so the likelihood of picking up people who do not meet the DRI for folate occurred more in the experimental group.

Mean ± SD Median 95% Confidence

95% CI

CPFFQ 309.31 ± 165 243 60.05

309.3+/-60.1GSFFQ 207.69 ±

103.28201 37.59

207.7+/-37.6

Correlation coefficient r = 0.32; this represents a positive, low correlation between the two surveys

Survey Differences

The CPFFQ assesses supplement use, whereas the GSFFQ does not.

Therefore, the percentage of people that met the DRI according to the CPFFQ did not meet the DRI according to the GSFFQ.

Questions?