Omega-3-Index Response to Eating Poultry Foods Naturally Enriched With Omega-3 Polyunsaturated Fatty Acids

STUDY RATIONALE

In this randomized, double-blinded, controlled trial, the investigators aim to quantify the impact of regular consumption of omega-3 PUFA enriched chicken-meat and eggs over a four month period, in a healthy Saudi population.

STUDY AIMS AND OBJECTIVES.

The primary objective of this study will be to assess the red blood cell omega-3 index response of healthy Saudi adults to regular consumption of omega-3 PUFA-enriched chicken-meat and eggs. The red blood cell omega-3 index is calculated as the sum of EPA and DHA expressed as a percentage of total fatty acids in erythrocyte (red cell) membranes.

Secondary objectives include;

• The assessment of red cell and plasma EPA, DPA and DHA responses to regular consumption of omega-3 PUFA-enriched chicken-meat and eggs.
• The comparison of baseline red cell and plasma levels of EPA, DPA and DHA, amongst Saudi residents who regularly consume oily fish with those that do not regularly consume oily fish, and
• The assessment of whether the red cell and plasma omega-3 index responses to the omega-3-PUFA enriched foods differs between those that do, and those who do not, include oily fish in their weekly diet.

TRIAL DESIGN.

This will be a randomised double-blind interventional study. The trial will be performed in accordance with the Declaration of Helsinki.

STUDY PARTICIPANTS

80 healthy, community dwelling, participants will be recruited to the study.

RANDOMIZATION AND MASKING

Participants will be randomized to either of two arms;

• Control / Placebo Intervention: Consumption of at least 4 portions of standard chicken-meat and at least 4 standard eggs per week, for 4 months.
• Experimental Intervention: Consumption of at least 4 portions of omega-3-PUFA enriched chicken-meat and at least 4 omega-3-PUFA enriched eggs per week, for 4 months.

STUDY CONDUCT

Participants will attend the study center at the screening and baseline visits and at study end (month 4). They will be contacted by telephone at monthly intervals (Months 1, 2 and 3).

At the screening visit, a comprehensive lifestyle and medical history will be taken, a food frequency questionnaire will be completed to capture food intake over the previous year; a 3 days food record will be arranged to capture the current dietary intake of participants; and satisfaction of the inclusion and exclusion criteria will be evaluated.

At the baseline visit, if all inclusion and exclusion criteria are satisfied, participants will be randomized to either the control or the interventional arm of the study.

At both the baseline and month 4 visits, height, weight, waist and hip circumference will be measured, allowing calculation of both the body mass index and the waist-hip ratio. At these two clinic visits fasting blood samples will be taken to allow measurement of plasma and red cell levels of EPA, DPA and DHA, and also to allow storage of plasma aliquots for future research measurements. Participants will be asked to fast, not drink tea or coffee, not smoke and not engage in intense exercise from midnight (minimum 8 hours), prior to the baseline and end-of-study visits. Participants may drink water and take essential medications on these mornings.

At the month 1, 2 and 3 telephone calls, and at the month 4 visit, frequency of consumption of chicken-meat, eggs and fish, during previous week, will be assessed, as will concurrent medications and participant wellbeing.

Participants will be asked to avoid taking long-chain omega-3 PUFA supplements, for the duration of the study.

NUTRITIONAL INTERVENTION

The poultry meat and eggs will be enriched by feeding chickens a complete feed which includes algae, which is a rich source of omega-3 PUFAs (OmegaPro, Humanitiv, Meath, Ireland). Omega-3 PUFA enriched chicken (whole chickens, breasts, thighs and drums) and eggs, or the appropriate control chicken and control eggs, will be delivered to the homes of study participants at regular intervals (weekly or two-weekly), so that both they, and up to three additional family members, will be able to eat at least 4 servings per week of chicken meat, and at least 4 eggs weekly over the 4 month study period. The chicken-meat will be delivered frozen, and the eggs will be delivered refrigerated.

MEASUREMENT OF RED CELL AND PLASMA LEVELS OF FATTY ACIDS

Measurement of plasma and red cell levels of EPA, DPA and DHA will be performed at a laboratory with specific expertise in lipid analyses. Total lipids will be extracted from plasma and red cells using a modified Folch method. Phospholipids will be separated from neutral lipids by 1-dimensional thin-layer chromatography. Fatty acid methyl esters will be prepared by direct transesterification and separated using gas chromatography-mass spectrometry allowing quantification of 28 distinct fatty acid peaks. Plasma levels of omega-3-PUFAs will be expressed in microgram/gram, and red cell levels as a percentage of total fatty acids in erythrocyte membranes. The erythrocyte or red cell omega-3 index is calculated as the sum of EPA and DHA expressed as percentage of total fatty acids in erythrocyte membranes.

STATISTICAL ANALYSIS

Analyses and Reporting The study will be analyzed on an intension to treat basis. Standard summary statistics (mean, standard deviation, median, range, %) will be used to describe baseline characteristics of the participants.

Repeated measures ANOVA will be used to compare the 2 study groups. The study will be reported in accordance with the CONSORT (Consolidated Standards of Reporting Trials) 2010 statement.

Sample Size Considerations The primary end point will be the change in red cell omega-3-index at 4 months. In previous studies, the standard deviation of repeated measures of the erythrocyte omega-3 index has been found to be 0.5%. Hence with 80 participants, the study will have in excess of 95% power to detect a difference of 1% in the change from baseline in the omega-3 index between those eating enriched foods versus those eating control foods, at a 2-sided alpha-level of 0.05.