1. Seasonal Availability, Culture, and Religious Practices Appear to Influence Fish Consumption Throughout the Year
Jennifer Hanson & Mark Haub
Kansas State University, Manhattan, Kansas
Background
Research studies on omega-3 fatty acids are hindered by the lack of a tool specifically designed to measure omega-3 intakes in U.S. populations. Compounding this problem is the fact that the number of omega-3 enriched foods available to consumers is rapidly growing.
Purpose
To assess question clarity and factors related to the test-retest reliability of a food frequency questionnaire (FFQ) specifically designed to measure dietary intakes of foods rich in eicosapentaenoic and docosahexaenoic acids.
Methods
A self-administered semi-quantitative food frequency questionnaire (FFQ) was used to measure consumption of foods rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Intake was recorded for the six-month period prior to administration of the FFQ. The instrument included items to capture intake of EPA and DHA from: 1) seafood, 2) poultry and eggs, 3) omega-3 enriched foods, and 4) dietary supplements. On hundred sixty-five college students completed the FFQ during its initial administration in May of The participation rate was 83.7%.
Of those students who took part in the initial survey, 54 agreed to complete the FFQ a second time. Forty-five of those who agreed to complete the survey a second time did so, thereby yielding a return rate of 83.3%.
Results
Results
Results
Conclusions
A large proportion of the participants had omega-3 intakes below the range generally considered to be ideal.
Overall test-retest reliability of the instrument is good.
A sizeable proportion of the participants indicated their fish consumption changed throughout the year due to cultural, seasonal or school-related factors. Participants who indicated their fish consumption was related to seasonal availability and those who said it was related to the school year both had significantly higher intakes of omega-3 fatty acids from seafood.
Only 7.4% (n = 12) of the participants felt one or more of the questions was difficult to answer; among those who experienced confusion, uncertainty regarding omega-3 enriched foods was cited by 75% (n = 8).
As indicated by participant feedback and the decreased test-retest coefficients, unfamiliarity regarding omega-3 enriched foods may be problematic when measuring intakes from these sources.
Additional work is needed to improve the reliability of the FFQ items related to omega-3 functional foods.
Test-Retest Reliability of Omega-3 Supplement Use
Retest
Initial Test No
Yes 38 1 3
Summary
Number of Subjects 42
Percent with exact matches
97.6
Cohen’s Kappa
.844 (p < 0.001)
Mann-Whitney U for Consumption Factors and Omega-3 Intake from Seafood
Factor n
Mean Rank U p
Culture/ Religion
Yes 29
84.90
1366
.103 No
117
70.68
Seasonal Availability 25
96.24
919
.002
120
68.16
School Year 53
96.14
1264
<.001 93
60.60
Types of Sushi Listed n
Percent
California Rolls 13
34.2%
Salmon 7
18.4%
Shrimp 3
7.9%
Philly/Cream Cheese
Eel 2
5.3%
Other 10
26.3%
Figure 1. Select Questions from Food Frequency Questionnaire
Acknowledgments
We would like to thank the students who participated in this study for their support.
Spearman Rank Order Correlation Coefficients for Omega-3 on Initial and Retest FFQ
Omega-3 Retest FFQ
Omega-3 Initial FFQ
Seafood
Canned Tuna
.80 (n = 44)**
Fried Fish
.64 (n = 43)**
Fried Shellfish
.70 (n = 44)**
Sardines
.83 (n = 41)**
Baked White Fish
.76 (n = 44)**
Baked Dark/Oily Fish
.48 (n = 43)**
Sushi
.58 (n = 43)**
All Seafood
.84 (n = 38)**
Other Foods
Dark Chicken
.79 (n = 43)**
Eggs
.67 (n = 45)**
All Seafood and Other
.78 (n = 36)**
Functional Foods
Omega-3 eggs
.52 (n = 44)**
Omega-3 margarine
.42 (n = 42)*
Omega-3 milk
.17 (n = 44)
Omega-3 juice
.14 (n = 44)
Total Functional Foods
.24 (n = 42)
Supplements
.86 (n = 42)**
Total All Sources
.86 (n = 31)**
* < 0.005; ** < 0.001
Summary
Intakes of Omega-3 fatty acids ranged from 0 to 2734 mg/day with a mean of mg/day. Sixty-four percent (n = 91) of the volunteers had omega-3 intakes below 130 mg/day.
Omega-3 intakes were non-normally distributed with positive skewing and values clustering at the low end.
Test-retest reliability correlation coefficients for each of the non-functional food items were significant and ranged from .48 to .83;
p <
Test-retest reliability for the overall scale (i.e., total omega-3) was .86 ; p <
Test-retest reliability correlation coefficients for each of the functional food items were low and/or non-significant.
Twenty-one percent (n = 35) of the participants had eaten sushi, 9.1% (n = 15) had taken an omega-3 supplement.
California rolls were the predominate type of sushi listed.
Discloser
Funding for this project was provided by:
Herbert D. and Nylda Gemple Research Award
Kansas State University Research Foundation Fellowship Award
University of Nebraska Impact of Sustagrain Barley Grant
Select Comments Regarding Questionnaire Clarity
“How do I know what is omega-3 enriched?”
“I'm not aware of my omega-3 intake.”
“Not sure whether or not I have eaten omega-3 enriched foods.”
“Explain omega-3 enriched foods.”
“I don't know if the stuff I eat is omega-3 enriched.”
“I don't know if foods are enriched.”
For further information
Please contact, Jennifer Hanson, Department of Human Nutrition, Kansas State University.
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