The skinny on tuna fat: health implications

Objective: Dietary n-3 (omega-3) and n-6 (omega-6) PUFA have significant implications in health and disease prevention. Marine life is rich in long-chain n-3 PUFA. Children and adults in North America are reluctant fish eaters; canned tuna is a common fish in children's diets. Although a multitude of tuna products are available, their respective PUFA contents have not been well described. The aim of the present study was to compare the fatty acid (FA) profiles of different commercially available US tuna products. Design: Fat and FA composition of eight products randomly selected from two US suppliers were analysed with capillary GC after lipid extraction. Setting: Large north-eastern US grocery store chain. Subjects: Canned tuna. Results: Energy from fat varied from 3 to 33% and the essential FA (EFA) linoleic acid (18 : 2n-6) and alpha-linolenic acid (18 : 3n-3) varied tenfold. DHA varied between 90 and 770mg/serving. The n-6: n-3 ratio was 3:1-4:1 in oil-packaged products, 2:1-7:1 in packaged tuna salads and 1:3-1:7 in water-packaged products. A similar magnitude of differences was seen in the ratio between arachidonic acid (20:4n-6) and DHA. Conclusions: Light tuna canned in water may be a better choice of providing n-3 PUFA to individuals in a healthy population, whereas oil-packaged products may be preferable for those individuals with a need for increased EFA, such as for patients with cystic fibrosis. Awareness regarding PUFA content may aid in consumer product choices and health-care provider advice.