Diets including avocados have a higher unsaturated to saturated fat ratio, which helps improve cardiovascular health, weight control, and cognitive function. For cardiovascular health, avocados are consistent with the American Heart Association’s Presidential Advisory Report recommending a shift from saturated to unsaturated fatty acids such as cis-MUFAs to promote healthier blood lipid profiles, including lowering LDL-C, a major cause of atherosclerosis ^[9][37]. Also, the avocados’ fat ratio helps improve vascular endothelial function by maintaining healthy postprandial FMD blood flow. The fat profile maintains low circulatory non-esterified fatty acids to optimize insulin sensitivity. This is critical as vascular endothelial cells depend on insulin activity for proper function. Also, the fatty acid profile likely reduces the risk of LDL oxidation, thus protecting against atherosclerosis ^{[10][11][12][13][14][15][16]}[13,38,39,40,41,42,43]. For weight control, higher oleic acid intake leads to lower fat storage compared to long-chain saturated fats, especially when consumed in a moderate refined carbohydrate diet ^[17][18][44,45]. The mechanisms include converting oleic acid to oleoylethanolamide in the intestine and liver, which helps induce satiety and increase energy expenditure by stimulating a cascade of biochemical activities ^[19][20][21][46,47,48]. Oleic acid-rich diets improve cognitive function compared to low fat and high SFA diets ^{[22][23][24][25][26][27][28]}[49,50,51,52,53,54,55]. Avocados’ healthy fatty acid ratio helps improve cerebral cortex blood flow, compared to long-chain saturated fats, to help assure the critical delivery of oxygen to the brain to match the increased needs of activated neurons ^[29][30][56,57].

Diets with avocados contain a good source of viscous and prebiotic fiber, which help improve all four identified avocado health benefits. For cardiovascular health, avocados are consistent with the Third Report of the National Cholesterol Education Program Expert Panel and meta-analyses of RCTs, which showed that one gram of viscous pectin could significantly lower TC by −2.7 mg/dL and LDL-C by −2.1 mg/dL ^[31][32][58,59]. Pectin also slows the progression of intima-media plaque deposits in the common carotid arteries ^[33][60] and 4 g of fruit fiber daily lowers the risk of coronary heart disease by 8% ^[34][61]. The major mechanism for pectin and other fiber components is to increase viscosity in the ileal region of the small intestine, leading to reduced efficiency of saturated fat and cholesterol absorption and bile acid reabsorption, thus increasing the uptake of circulatory LDL-C by the liver to reduce the circulatory LDL-C load. Fruit fiber fermentation in the microbiota of SCFAs also reduces hepatic fatty acid synthesis to help lower LDL-C formation ^[35][36][62,63]. For weight control, numerous studies show that adequate fiber intake reduces body weight, waist circumference, and visceral fat, especially in women, compared to lower fiber diets ^{[37][38][39][40][41][42][43]}[64,65,66,67,68,69,70]. The main mechanisms for increased fruit fiber intake and weight control are increases in gastrointestinal bulking volume that promote satiety hormones and reduce macronutrient bioavailability (e.g., reduced metabolizable energy), and promoting healthier microbiota metabolites and microflora that support a more metabolically lean phenotype ^{[2][4][44][41][45][46]}[2,4,25,68,71,72]. For cognitive function, daily intake of a prebiotic type fiber of at least 5–10 g/day can help restore or maintain colonic microbiota homeostasis to reduce systemic inflammation and improve insulin sensitivity, which helps optimize the gut-brain axis for better hippocampal and frontal cortex function ^{[47][48][49][50][51]}[73,74,75,76,77]. In young adults, avocado intake improved cognitive functions such as increased processing speed, sustained attention, and working memory in midlife ^[52][78]. For colonic microbiota health, adequate intake of fiber, especially prebiotics, can generate metabolically active SCFAs ^[48][49][74,75]. Fruits are among the best fiber sources for improving colonic microbiota health. As they ripen, their semi-hydrated cell wall fiber components, including pectin, hemicellulose, and cellulose, become progressively disassembled, and with eating and digestion, their fiber components become highly accessible to the colonic microbiome for fermentation ^[2][7][2,7]. Overall, fruit fiber acts as a prebiotic to help re-balance the colonic microbiota towards a higher anti-inflammatory profile by increasing the Bacteroidetes/Firmicutes ratio, increasing microflora diversity, optimizing colonic mucosal barrier, and lowering levels of primary and secondary bile acids, which are important for maintaining overall health ^[2][53][54][2,26,34].

For weight control, avocados with an ED of 1.6 kcal/g (79% by weight of water and fiber) support better weight management and improve body composition ^{[55][56][44][53][57][58][59][60][61][62]}[23,24,25,26,27,28,29,30,31,32]. Most fresh fruits have a high bulk volume and low energy density (ED), ranging from 0.3 to 1.6 kcal/g ^[2][5][6][7][2,5,6,7]. Humans tend to have relatively low energy regulatory sensitivity to food or meals with an ED greater than 1.75 kcal/g, leading to a positive energy balance and thus to an increased risk of weight gain ^[63][79]. According to NHANES analyses, the estimated US mean daily ED is 1.9 kcal/g, consistent with Western diets low in fruit and vegetable intake resulting in a higher risk of being overweight or obese over time ^[64][80]. A longitudinal study in young overweight women consuming higher ED diets ≥ 1.85 kcals/g showed an average weight gain of 6.4 kg over six years ^[65][81].

Avocados are a unique, oleic acid-rich fruit that provides a highly bioavailable source of lutein, and the lipid boosts carotenoid absorption from co-consumed fruit and vegetables ^[66][67][35,36]. This nutritional feature supports cardiovascular health and cognitive function. For cardiovascular health, highly bioavailable lutein from avocados helps protect LDL from oxidation, decreasing the uptake of macrophages, and helps protect against atherosclerosis pathogenesis ^[68][69][82,83]. Observational studies show that higher lutein intake and blood levels are moderately associated with lowered coronary heart disease and stroke risk ^[70][84]. Combinations of lutein and lycopene are twice as effective at reducing carotid artery intima-media thickness than lutein alone ^[71][85], which may be achieved by consuming avocados with salsa or other tomato-based foods ^[66][67][35,36]. This can significantly lower mean LDL-C, increase FMD, and decrease systolic blood pressure ^[72][86]. For cognitive function, a higher intake of carotenoid-rich fruit and vegetables is generally associated with enhanced cognitive function in younger and older adults ^[73][74][87,88]. Several RCTs of lutein and zeaxanthin supplements after 12 months show improved visual episodic memory performance in young and middle-aged adults, and improved inhibition and attention performance in middle-aged and older adults compared to controls ^[75][89]. Importantly, avocado lutein is more highly bioavailable than that of supplements or low-fat fruits. Lutein and zeaxanthin can cross the blood-brain barrier and direct their antioxidant and anti-inflammatory functions to act directly on the brain structure and function with selective distribution to the prefrontal cortex, visual cortex, hippocampus, and central retina, as measured by macular pigment optical density ^{[73][74][75][76][77][78]}[87,88,89,90,91,92]. The concentration of lutein in the brain is higher in the prefrontal cortex than other regions and positively correlated with the gray matter volume in the parahippocampal gyrus, suggesting that lutein plays a role in memory and inhibition functions ^{[79][61][80][76][77][78]}[18,31,33,90,91,92].