A cross-sectional set of qFAF images was acquired from 67 control rhesus monkeys (
Macaca mulatta) ranging from 3 to 26 years of age that were fed a standard laboratory diet (Lab Diet Monkey Diet 5037/5038) providing adequate levels of L/Z and ω-3′s and supplemented with fresh fruits and vegetables. In addition, qFAF images were acquired from rhesus macaques (ages 18–24 years,
n = 17) fed one of three L/Z-free semipurified diets from birth. All semipurified diets had the same overall level of fat as the standard diet. The three diets were identical except for their sources of dietary fat, which were designed to provide widely different content of ω-3′s: (1) A high α-linolenic acid (ALA; 18:3ω-3) diet (ω-3 adequate;
n = 7), with soybean oil as the sole dietary fat, contained 8% (as weight % of total fatty acids) of ALA, the precursor of DHA, and 54% linoleic acid (18:2ω-6), the primary dietary omega-6 fatty acid providing a ω-6:ω-3 ratio of 7. This diet has been shown to support normal levels of retinal DHA. (2) The second diet (also ω-3 adequate;
n = 3) consisted of a mixture of plant, animal, and fish oils that provided the preformed long-chain polyunsaturated fatty acids: 0.6% DHA (22:ω-3), 0.2% EPA (20:5ω-3), and 0.2% arachidonic acid (20:4ω-6); plus 1.4% ALA. This diet led to retina levels of DHA similar to the high ALA group, although circulating levels of DHA were higher. In our previous studies of retinal function,
28,47 results were equivalent between the latter two diet groups, and, therefore, data for the two groups were combined in this study to increase
n. (3) The ω-3–deficient diet (
n = 7) contained <0.3% ALA and 54% linoleic acid, with an ω-6:ω-3 ratio of 180, from a 1:1 mixture of safflower and peanut oils. In addition to the low level of ALA, the high ω-6:ω-3 ratio reduces ALA uptake and DHA synthesis due to competition between the two fatty acid classes. We previously showed that this diet, fed during gestation and from infancy, reduced retina levels of DHA by 80% and altered retinal function.
28,29,47