The avocado (Persea americana) is a shrub or small tree that may reach up to 20 m in height. Some varieties have flowers that produce early in the season and/or fruits with an early ripening period (i.e. summer). Other varieties have late flowering and/or late ripening periods (i.e. fall and winter). Avocados classified according to their flowering behavior (A or B) are also known as Mexican, Guatemalan, or West Indian along their geographic origin. Avocados are rich in monounsaturated fatty acids (MUFA) owing to their high oleic acid content. AVs are low in saturated fatty acids and hence, cholesterol free.
Avocados are unique fruit because of their high fat content, mostly monounsaturated fats which are considered as “heart-healthy” fats. They also contain compare levels of nutrients than other common fruits. For instance, avocados are one of the lowest sugar containing fruits. They are also rich in potassium with almost 2 times more than banana; fiber comparable to dragon fruit; and lutein & zeaxanthin compared to broccoli and other dark leafy greens. One serving of avocado (16 oz) provides 100% more potassium than bananas, 35% more fiber than dragon fruits, 250% more lutein & zeaxanthin than broccolis, and 200% more folate than tomatoes (L. Dreher et al., 2021). With this unique and high nutrient density profile, many studies have been conducted to investigate the impact of avocado consumption on various health benefits (Jyoti Bhuyan et al., 2019). (Table 1) lists the avocado’s nutrient profile per 100g serving.
History and Origin
The avocado (Persea americana) is a buttery, rich, and creamy-textured fruit that originated in southern Mexico between 3000 and 5000 years ago. It was spread to the Pacific coast of Guatemala, where it was cultivated with cultivation continuing to the Andes and northern South America. Cultivation in California began in 1871, and in Florida in 1833. The Hass avocado, a mutation from the Guatemalan race, was one of the first cultivated globally (L. Dreher et al., 2021). Avocado is a unique singular fruit having a nutrient and phytochemical dense profile that includes atypical compositional components. Avocados have a ratio of fat/energy content of >50%, but they are unique in having 60% of their total fat content as MUFA with <20% of fat calories as polyunsaturated fats.
Avocados first began cultivation in Pre-Columbian times in southern Mexico and Central America and were eaten by the Incas and Aztecs before the arrival of Europeans. It was introduced into Hawai’i in 1825, Brazil in 1809, Florida in 1833, Chile in 1827, Dominican Republic in 1857, and California in 1871. Avocados were not stateside in 1880, but the Guatemalan and Florida strains were produced in California (Jyoti Bhuyan et al., 2019). The Hass avocado is a hybrid from the Guatemalan race and flower type B. The cultivation of avocados spread when tasted by Queen of Spain and avocado became a royal fruit.
Nutritional Profile
An avocado is a smooth-skinned, fleshy fruit with a single large seed that contains a lot of monounsaturated fats. It grows in warm climates and comes in many varieties, distinguished by variations in peel color and texture, shape, and size. Over the years, avocados have gained popularity because of their delicious taste and creamy texture, making them the ideal addition to a salad or the remarkable base for a world-famous spread-vegetable guacamole. The avocado fruit, known for its high nutritional value, is native to the American continents, with evidence showing its cultivation originated in Mexico and Central America.
Avocados are regarded as an excellent source of nutrition because they are cholesterol-free and low in saturated fat. Over 70% of the fat content comprises healthy MUFAs, particularly oleic acid. MUFAs help maintain serum lipids by lowering bad cholesterol levels (LDL cholesterol) and increasing good cholesterol levels (HDL cholesterol). They are also a good source of dietary fiber, potassium, vitamins, minerals, and phytochemicals (Jyoti Bhuyan et al., 2019). Bioactive components in avocados may have important health implications. While a lot of attention has been devoted to studies examining the relation between the processing of food products and their bioactive content, less research has been done to track and study the relationship between the bioactive compounds naturally found in food products, their bioavailability, and their effects on human health (L. Dreher et al., 2021).
Cardiovascular Health Benefits
There is a growing interest in the relationship between food consumption and specific cardiovascular health benefits, particularly in lowering blood cholesterol concentrations. Avocados are a unique food source that is particularly high in bioactive nutrients, especially a monounsaturated fatty acid (FA) oleic acid, lutein, and other carotenoids such as zeaxanthin and β-cryptoxanthin. The beneficial effect of oleic acid is highlighted in epidemiologic studies since it is the main fatty acid in virgin olive oil. This review outlines the results of clinical trials, cohort studies, and biological mechanisms addressing the cardiovascular health benefits of avocados (L. Dreher et al., 2021). Because lutein is highly bioavailable from foods, it is feasible for avocados to provide large amounts of this carotenoid, which has many cardiovascular health benefits.
Because people tend to consume avocados in combination with other foods, it would be good to study the cardiovascular health benefits of avocados when consumed as part of a mixed meal. For example, a study addressed the cardiovascular health benefits of avocado-enriched salsa when consumed with homemade corn tortilla chips that were deep-fried in avocado oil. Similarly, since people with metabolic syndrome and at high risk for cardiovascular diseases may benefit from eating avocados, clinical studies in people with differing weight, age, and health indices would be desirable (Jyoti Bhuyan et al., 2019). It may also be beneficial to investigate the cardiovascular health benefits of processed products made from avocados, especially the pulps, peels, and seeds that are currently treated as waste products.
Effect on Cholesterol Levels
Avocado is well known for its health benefits due to its nutrient-rich and bioactive properties. Cardiovascular diseases, including coronary heart disease (CHD), cerebrovascular stroke, arrhythmias, and heart failure, are the leading cause of death globally. Several studies reported that atherosclerosis is often the basis for the aforementioned diseases, which is caused by the accumulation of lipids and inflammatory cells in the arterial wall. Lipids in the blood are carried by lipoproteins, some of which are atherogenic, including low-density lipoproteins (LDL). Lesser amounts of high-density lipoproteins (HDL) are atheroprotective, and the ratio between the two lipoproteins is key in regulating cardiovascular disease risk. Since its peak in 1992, CHD deaths have fallen by 65% in the US, Canada, and other Northern European countries due to lifestyle changes. However, declines in mortality have not been evenly distributed around the world, including supporting evidence. For cardiovascular health, highly bioavailable lutein from avocados helps protect LDL from oxidation, decreasing macrophages’ uptake, and protecting against atherosclerosis pathogenesis. Observational studies show that higher lutein intake and blood levels are associated with lowered coronary heart disease and stroke risk (L. Dreher et al., 2021). Furthermore, combinations of lutein and lycopene are effective at reducing carotid artery intima-media thickness (IMT), which may be achieved by consuming avocados with salsa or other tomato-based foods. Through these mechanisms, it can lower mean LDL-C, increase FMD, and decrease systolic blood pressure.
Blood Pressure Regulation
Hypertension is a condition where the force of the blood against the artery walls is too high. A systolic blood pressure (SBP) reading of 140 or greater, or a diastolic blood pressure (DBP) reading of 90 or greater is classified as hypertensive. Healthy blood pressure is a higher priority than both cholesterol and blood glucose; however, diet can play a pivotal role in maintaining healthy blood pressure levels. There exists large epidemiological evidence suggesting that diet can significantly influence blood pressure through the use of food groups and salts; thus, dietary manipulation cannot only lower blood pressure but maintain healthy blood pressure levels (L. Dreher et al., 2021). The human diet consists of many food groups, many of which have no proven effects on blood pressure. However, may nevertheless play a role in general heart health. There exists strong evidence that a diet rich in unsaturated fats is correlated with lower concentrations of low-density lipoprotein cholesterol (LDL-C) and blood pressure (BP), and a more favorable endothelial function. The above food groups contain a strong source of monounsaturated fatty acids (MUFAs), which is primarily oleic acid (C18:1n-9). MUFA-intake, especially oleic C18:1n-9 acid, has also been linked with cardioprotective effects (Jyoti Bhuyan et al., 2019). Oleic acid is abundant in avocado, a fruit native to Mexico and Central America that has been consumed and cultivated worldwide for thousands of years and is often referred to as an excellent source of MUFA. Avocado consumption has been significantly associated with lower systolic blood pressure mainly through the consumption of Hass avocado.
Weight Management
Obesity has become a worldwide epidemic, posing significant challenges for both developing and developed countries due to environmental and socioeconomic consequences. In the United States, the total prevalence of obesity is 37.9% among adults, while overweight or obesity status is present in 70.7%. According to the National Heart, Lung, and Blood Institute, excess adiposity is a major contributor to cardiovascular disease, type 2 diabetes, and certain cancers, highlighting the importance of weight management as a risk reduction factor. From a lifestyle perspective, effective methods that reduce adult weight gain, or promote maintenance of a healthy weight prior to significant weight gain, would be valuable and are needed (Heskey et al., 2019).
Recent interest has focused on the role of whole foods in weight management. Consuming nutrient-dense, whole food choices instead of highly processed, energy-dense foods may help abate adult weight gain and prevent or reduce the risk of being overweight or obese. Hass avocados (Persea americana) meet these criteria as a whole food, as they are a nutrient-dense and low-calorie fruit rich in dietary fiber, phytochemicals, and healthy fats (L. Dreher et al., 2021). It has been found that individuals with avocado intake in their diet have lower fasting blood glucose levels and a reduced probability of an elevated 2-hour serum insulin response, suggesting a potential role of avocados in reducing the risk of diabetes. As a result, it is hypothesized that avocado intake may reduce the risk of weight gain and excess adiposity, particularly due to its high levels of dietary fiber, phytochemicals, and monounsaturated fatty acids (MUFAs).
Satiety and Reduced Caloric Intake
Weighing an average of 200 g, the dark green Hass avocado is a nutrient-dense fruit rich in healthy fats, dietary fiber, vitamins, and phytochemicals, yet low in sugar and carbohydrates. (L. Dreher et al., 2021). Data presented here demonstrate that a whole Hass avocado (WA) integrated into a breakfast meal caused appetite regulation and triglyceride metabolism modulation compared to a control meal (CON) consisting of no avocado, as evidenced by improved inflammatory and metabolic markers. WA effectively controls appetite by regulating postprandial appetite, energy balance, and food intake. WA reduced energy intake at the lunch meal (−276 kcal) compared with CON and−158 kcal compared with a high fat and fiber avocado-free breakfast meal, indicating that WA promotes a net caloric deficit. The modulation of TAG metabolism after WA was observed as a lower total AUC for TAG from 0 to 8 h and an increased AUC for TAG at 8 h compared with CON, while there was no difference compared with the other two meals. A whole avocado breakfast meal integrated high fat and fiber from avocados attenuated hunger throughout the 6-h post-breakfast period in overweight adults compared with the control avocado-free breakfast meal.
Skin and Hair Health
The skin and hair health benefits of avocados are attributed to their antioxidant properties. Research has shown that the pulp, seed, and oil from Hass avocados can act as antioxidants in various models (L. Dreher et al., 2021). For example, it was reported that a crude avocado fruit peel and pulp extract prevented UV-induced epidermal hyperplasia in mouse skin. The efficacy of the pulp or oil from Hass avocados on UV-induced skin aging in humans was also investigated, revealing that it could reduce wrinkle formation and improve skin elasticity and hydration. These beneficial effects are likely due to the antioxidant effects of carotenoids and tocopherols present in Hass avocados (Jyoti Bhuyan et al., 2019). The pulp alone contains these two lipophilic antioxidants at a high concentration and can protect cultured fibroblasts and keratinocytes from UVB-induced cell death.
Preliminary research has also been conducted on the skin or hair health benefits of avocados. An intermittent thermal treatment for Asian straight hair was developed to make it a two-in-one service of permanent straightening and hair care. The hair structure was modified using a polethylene glycol compound for hair straightening and avocado oil for care, improving hair elasticity, strength, moisture, and shine while reducing volume and frizz. Using Phytosqualans®, the Brazilian avocado oil, reduced the appearance of “chicken skin” on bumpy skin (keratosis pilaris). As for the practical usage of the control and treatment using Peru avocado oil from Hass avocados to keep the pilosebaceous unit clear is currently considered, as the pulp of Peru avocados is discarded.
Antioxidant Properties
A data base search comprising of publications in scientific journals, brochures and research papers available on the internet with credible credibility was carried out to focus on the evaluation of the possible use of avocado as a natural cosmetic. There has been growing interest in the formulation and use of natural cosmetics because of the possible side effects of synthetic cosmetics . Apart from the fruit of the avocado tree, which is a major component of the diet in tropical countries, the peel and seed are discarded as industrial waste. However, the pulp, seed and peel of the avocado have been reported to possess antioxidant properties suggesting their possible role in protecting skin and hair from the deleterious effects of free radicals (L. Dreher et al., 2021). Avocado contains bioactive compounds such as carotenoids, phytosterols and polyphenols that are important for maintaining cellular health. Carotenoids protect cells from UV radiation-associated oxidation and inflammation. Phytosterols have been shown to lower blood total cholesterol levels and reduce the risk of coronary heart disease. Polyphenols are a large group of compounds which protect cells from free radical damage, oxidation and inflammation.
Avocados offer a multitude of health benefits, making them a valuable addition to a healthy diet. Due to their unique nutrient profile and high fat content, avocados can be particularly beneficial for heart health, weight loss, digestion, and improving appetite. Several studies have shown that avocados can help reduce the risk of chronic diseases such as type 2 diabetes, heart disease, stroke, certain cancers, and eye disease, supporting findings from previous epidemiological studies. The mono-saturated fats in avocados can help prevent the onset of heart disease and lower blood cholesterol levels (L. Dreher et al., 2021). In addition, the potassium content in avocados is greater than that in bananas, helping to regulate blood pressure and reducing the risk of high blood pressure, stroke, and cardiovascular disease. In a weight-loss-friendly food match with chia seeds, avocado consumption helped keep energy intake more balanced and especially lower in cholesterol (Jyoti Bhuyan et al., 2019).
Moreover, avocado’s lipid profile can help improve skin and hair health. It contains nutrients, such as oleic acid and amino acids, which cannot be synthesized by the body, thereby preventing the effects of hydrogenation and skin dryness. As a result, the seed oil derived from avocados is commonly used in various skin-care products. Additionally, studies report the presence of 20 amino acids in avocados, enabling them to nourish the skin while also being lightweight, fast-absorbing, and not causing irritation that is commonly encountered with other oils. Avocado oil can benefit dry scalp conditions in hair care products and can be followed up with pre-application of avocado oil prior to dyeing and heat styling treatments. These health benefits and consumption recommendations are based on dietary guidelines in North America, where five servings of fruit and vegetables a day is commonly suggested. Thus, increasing the intake of avocados is encouraged because of their substantial health benefits.