TABLE 3.

Lipid diets and their effects on AD.

Lipid diet interventions	Effects on AD
Algal DHA#; 2 g daily for 18 months	Supplementation with DHA compared with placebo did not slow the rate of cognitive and functional decline in patients with mild to moderate Alzheimer’s disease (Quinn et al., 2010).
Consumption of fish once or more per week	In adults above the age of 65, participants who consumed fish once or more per week had 60% less risk of developing Alzheimer’s compared to participants who rarely or never ate fish (Morris et al., 2003).
Omega-3 PUFA; 600 mg EPA and 625 mg DHA daily for 4 months	In adults with mild cognitive impairment and probable AD, omega-3 supplementation had negligible effects on cognition or mood (Phillips et al., 2015).
EPA-DHA for 26 weeks; stratified into high-dose (180 mg EPA-DHA daily) and low-dose (400 mg daily)	In cognitively healthy adults over 65 years old, there were no significant differential changes in any of the cognitive domains for either low-dose or high-dose fish oil supplementation compared with placebo (van de Rest et al., 2008).
Study participants are postmenopausal women (60−84 years); 1g DHA, 160 mg EPA, 240 mg Ginkgo biloba, 60 mg PS, 20 mg per day for 6 months	In a randomized, double-blind study, a high dose of omega-3 nutrients has cognition and mobility benefits to older women (Strike et al., 2016).
DHA-EPA; 1.7 g DHA and 0.6 g EPA daily for 6 months (OmegAD Study)	Omega-3 fatty acids did not delay the rate of cognitive decline, nor did it have marked effects on neuropsychiatric symptoms except for possible positive effects on depressive symptoms in non-APOE4 carriers and agitation symptoms in APOE4 carriers (Freund-Levi et al., 2006; Freund-Levi et al., 2008). Plasma levels of AA decreased while DHA and EPA levels increased at 6 months. Specialized pro-resolving mediators (SPMs) do not change in the omega-3 group but a decrease in the placebo group. SPM changes associate with cognitive changes in AD (Lopez et al., 2011).
Omega-3 PUFAs; 1.8 g daily for 24 weeks	The omega-3 supplementation treatment group showed significant improvement in the Alzheimer’s Disease Assessment Scale compared to the placebo group in participants with mild cognitive impairment. However, there was no significant improvement in Alzheimer’s disease study participants (Chiu et al., 2008).
Supplementation with omega-3 fatty acids alone or omega-3 plus alpha-lipoic acid; 675 mg DHA and 975 mg EPA or 675 mg DHA and 975 mg EPA plus 600 mg lipoic acid daily for 12 months	Combining omega-3 fatty acids with lipoic acid slowed both cognitive and functional decline in mild to moderately impaired AD participants over 12 months compared to placebo (Shinto et al., 2014).
3 DHA exposure variables used in separate analyses; plasma DHA, dietary DHA, and consumption of cold-water fish	Plasma and dietary DHA were associated with a decreased risk of dementia and AD (Lopez et al., 2011).
Arachidonic acid and DHA supplementation;240 mg of AA and DHA daily for 90 days	Participants with mild cognitive impairment showed a significant improvement in the immediate memory and attention score compared to placebo, but there was no significant improvement in participants with AD (Kotani et al., 2006).
Docosahexaenoic acid-concentrated fish oil supplementation; 430 mg of DHA and 150 mg of EPA daily for 12 months	In participants with mild cognitive impairment, supplementation resulted in a significant improvement in short-term memory, working memory, immediate verbal memory, and delayed recall capability (Lee et al., 2013).
Fortasyn Connect supplementation; 125 mL once-a-day drink containing Fortasyn Connect for 24 months (LipiDiDiet Trial)	In individuals with prodromal AD, Fortasyn Connect supplementation had no significant effect on neuropsychological test battery results (Soininen et al., 2017).
FINGER Study − Dietary intervention using a diet with 10−20% of daily energy (E%) from proteins, 25−35% from fat (less than 10E% from SAFA, 10−20% from MUFA, 5−10% from PUFA (including 2,5−3 g/day n-3 fatty acids); 45−55% from carbohydrates (less than 10% refined sugar); 25−35 g/day dietary fiber; less than 5 g/day salt; and less than 5 E% from alcohol for 2 years	In adults over 60 years old, there was a significant beneficial intervention effect on overall cognitive performance, including memory, executive function, and psychomotor speed (Rosenberg et al., 2020).

^#DHA, Docosahexaenoic acid (C22:6, n-3); EPA, Eicosapentaenoic acid (C20:5, n-3); MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; SAFA, saturated fatty acids.