http://www.cnpp.usda.gov/sites/default/files/healthy_eating_index/HEI2010-UpdatePaper.pdfWe measured diet quality using the modified Alternative Healthy Eating Index. Cox proportional hazards regression was used to determine the association between diet quality and risk of ≥3-point decline in Mini-Mental State Examination score, and reported as hazard ratio with 95% confidence intervals with adjustment for covariates.
During 56 months of follow-up, 4,699 cases of cognitive decline occurred. We observed lower risk of cognitive decline among those in the healthiest dietary quintile of modified Alternative Healthy Eating Index compared with lowest quintile (hazard ratio 0.76, 95% confidence interval 0.66-0.86, Q5 vs Q1). Lower risk of cognitive decline was consistent regardless of baseline cognitive level.
It's interesting in the healthy eating index, "the type of fat is more important than the total amount of fat and call for replacing saturated fatty acids with monounsaturated and polyunsaturated fatty acids. In the HEI-2010, the ratio of unsaturated fatty acids to saturated fatty acids is used to capture the concept of replacement and the relative balance of the two. This ratio has been used as part of another diet quality score. The Fatty Acids component is classified as an adequacy component to reflect the health benefits of poly-and monounsaturated fatty acids. In the USDA Food Patterns, the values of this ratio range from 2.5 to 2.6 among the various calorie levels. The least restrictive value of 2.5 was chosen as the standard for the maximum score. The approach for setting the minimum score is described below. Because the Dietary Guidelines also include the DASH Eating Plan as an illustrative dietary pattern, the ratio of unsaturated to saturated fatty acids in the various diets used in the DASH trials was also reviewed. The achieved diets had ratios of 2.4 to 3.1, suggesting that 2.5 is a reasonable standard."
I'm curious how PUFA factors into this ratio. While keeping SFA lower, I feel like the more MUFA the better, but I don't feel that way about PUFA. Right now in my low-SFA experiment, my unsaturated:saturated ratio is 3.7 (evoo+nuts+seafood), going up over 4.0 on higher fat days, although total PUFA is up around 11.8g with a 2.8 n-6:n-3 ratio.