Egg Fortification with n-3 Polyunsaturated Fatty Acids (PUFA): Nutritional Benefits versus High n-6 PUFA Western Diets, and Consumer Acceptance.

As high dietary n6 polyunsaturated fatty acids and n6 to n3 PUFA ratio may contribute to many western ailments, increasing n3 PUFA in foods could be beneficial. The nutritional significance of n3 PUFA fortified egg vs. enzymatically competitive high n6 PUFA diets is debatable. To evaluate the dietary contribution of ‘field fortification’ of eggs by adding n3 PUFA to high n6 PUFA hen feed and to assess whether it meets consumer preferences. Laying hens (n of 3500) were fed n3 PUFA-fortified (5 percent extruded linseed) feed or standard (control) feed for 5 weeks. Nutritional significance was evaluated for western (American, Israeli) populations.
Compared to regular (control) eggs, fortified eggs yielded a 3.8 fold increase in total n3 PUFA,  6.4 fold alpha linolenic acid (18:3), and 2.4 fold docohexaenoic acid (22:6). N6 to n3 PUFA ratio decreased 3.6 fold, and n6 to n3 long chain PUFA ratio (AA to DHA) 3.0 fold (P < 0.0003). Sensory evaluations were not significantly different. Egg cost increased by 1.5 to 3.0 percent. Fortified egg n3 PUFA content averaged 14.3 percent of the current intake of Americans and 15.9 percent of Israelis – 9.8 and 10.6 percent of upper Dietary Reference Intakes, respectively. Egg DHA content averaged 33.7 and 41.4 percent of upper DRI. Current cholesterol intakes average 281 and 263 mg/day (median 214 and 184 mg/day) including 0.7 and 0.5 egg/day; reported hypercholesterolemia rates are 17.7 and 16.5 percent, respectively. Effective concentration and transformation of supplemental n3 PUFA LCPUFA from feed to egg substantially enhanced egg n3 PUFA percent DRI, particularly of DHA, critical for health but often deficient. Such land based n3 PUFA LCPUFA fortification may be applicable to high n6 PUFA diets, fitting within cholesterol limitations and market criteria. It may contribute to general health and specific requirements (i.e., pregnancy and lactation), with possibilities of wide accessibility and standardization. (Authors abstract)

It has been suggested that high dietary n6 polyunsaturated fatty acids (PUFA) and n6 to n3 PUFA ratio play a role in the high rates of chronic disease in western countries such as the United States, northern Europe, and Israel. As egg fatty acid profiles are highly dependent upon feed given to laying hens, they could become a significant source of n3 PUFA and LCPUFA. High bioavailability of egg alpha linolenic acid (18:3 n3) and DHA has been shown by increased cellular DHA levels in consumers as well as a reduced n6 to n3 PUFA ratio [15] and a significant reduction in plasma triglycerides. However, western eggs, i.e., American and Israeli, typically have a very high n6 PUFA content relative to n3 PUFA (n6 to n3 PUFA ratio ≥ 17.4 to 1). Feed with high n6 PUFA may competitively inhibit transformation of added n3 PUFA, as both n6 and n3 PUFA are metabolized by the same enzyme. This study addressed the feasibility of adding a vegetal (linseed) n3 PUFA source to high n6 PUFA hen feed to attain an egg that may contribute significantly to dietary fatty acid balance in high n6 PUFA western diets, and that may be readily accepted by consumers. Consumption of one fortified egg, with increases in total n3 PUFA by 3.8 fold and DHA by 2.4 fold, could make a significant dietary contribution, particularly of n3 LCPUFA, with DHA content equaling 33.7 and 41.4 percent of the upper DRI for Americans and Israelis, respectively. The highly effective incorporation and transformation of supplemental feed ALA to egg yolk lipids enables fortified egg to become a significant dietary source of DHA. The recommended intake of two 100 g servings/week of fatty fish [6] could provide 350 to 870 mg/day n3 PUFA (mostly LCPUFA) while one fortified egg yielded nearly 260 mg total n3 PUFA, approximately 100 mg as DHA. Where daily consumption of 0.7 (United States) and 0.5 (Israel) regular egg/day contributes only a minor amount of n3 PUFA, increasing daily consumption to a whole fortified egg could double the current dietary DHA intake in men and women. As previous research has shown a significant positive impact of consumption of n3 PUFA-fortified eggs, with no noted negative effects, it has been suggested that they may be used as one means of increasing n3 PUFA consumption to meet current recommendations [8]. The present study suggests that simple and low cost n3 PUFA egg fortification may yield a significant dietary contribution, especially a high percent DRI of DHA, and could be relevant to the United States, Israel, and other western countries that have high total n6 PUFA and relatively low n3 PUFA intakes. (Editors comments)