Evidence-based health benefits of Hass avocado

Human authored, evidenced-based – 8 min read

The health benefits of avocado
This blog post will evaluate the published research discussing the benefits of consuming an avocado-rich diet to that of a number of avocado-free diets on various health outcomes, with a particular emphasis on the Hass avocado variety.

Nutritional composition of avocados
The humble avocado (Persea americana) is a tropical fruit that grows almost everywhere in the world but originated in Mexico and South America. There are 50 different types of avocado, but the most well-known and sold type is the Hass. Due to its beneficial properties and popularity, avocado has been used by both the food and cosmetic industries. What many readers may be surprised to learn, is that the pulp of the Hass avocado is mostly water by content ⁽¹⁾:

– 72% water
– 10% fat
– 7% carbohydrates
– 5% dietary fibre (70% insoluble, 30% soluble)
– 2% protein.

The fat content is higher than other fruits, however, 71% of the fat content is monounsaturated fatty acids (MUFA), the same type of fat present in olive oil, with 13% as polyunsaturated fatty acids (PUFA), and 16% is saturated fatty acids. Hass avocados contain several phytochemicals and nutrients, and each of them plays a specific role in preventing CVD and improving the blood lipid profile (5). With regards nutrients, avocados contain good amounts of vitamin E, magnesium, potassium, and fibre, higher intakes of which are associated to beneficial cardiovascular outcomes ⁽²⁾. Click on the drop-down boxes below to learn more about the nutritional composition of Hass avocados per 100g.

Avocados and cardiovascular disease (CVD)
According to global estimates, poor diet is responsible for 255 million disability-adjusted life years and 11 million deaths ⁽³⁾. Additionally, higher intakes of refined carbohydrates, salt, and saturated fat, as well as lower intakes of fibre-rich foods (vegetables, fruit, and whole grains), are consistently linked to various cardiometabolic risk factors ⁽⁴⁾.

High blood cholesterol, particularly low-density lipoprotein (LDL) particles commonly referred to as ‘bad cholesterol’, is a major risk factor for coronary heart disease (CHD), contributing to plaque build up and narrowing of the arteries (fig. 2). Conversely, higher levels of high-density lipoprotein (HDL), often referred to as ‘good cholesterol’, are associated with a lower risk of coronary heart disease. To reduce blood cholesterol levels, public health recommendations generally include lowering overall dietary fat, increasing fibre and sources of polyunsaturated (omega 6 & 3) fatty acids in the diet.

Other risk factors, such as the oxidative alteration of LDL particles is increasingly being recognised as a key player in the pathophysiology of atherosclerosis ⁽⁵⁾. Oxidised LDL (oxLDL) are taken up by macrophages (immune ‘scavengers’) resulting in significant production of cholesterol-rich foam cells that accumulate in the artery wall over time narrowing the passage of blood, oxygen and nutrients (fig. 3) to cells and tissues the require them. Many longitudinal studies have demonstrated a high plasma oxLDL concentration as an independent risk factor for CVD, whilst many foods, such as avocados, have been linked to a reduced risk of CVD ⁽⁶⁾.

Clinical trials have generally showed that avocados may also support healthy blood vessel function ^{(5) (7)}, although not all studies agree ⁽¹⁵⁾, improve insulin sensitivity and reduced c-reactive protein, a pro-inflammatory mediator ⁽⁹⁾ . Other clinical trials in overweight or obese adults with elevated cholesterol, have shown that consuming one avocado acutely, or over several weeks, can improve various cardiometabolic parameters. The observed effects were:

– 1 avocado p/d added to a moderate fat diet over 4 weeks significantly lowered total cholesterol and ‘bad’ LDL cholesterol vs a low-fat, or avocado-free moderate fat diets ⁽¹⁰⁾

– 1 or 2 avocados p/d between 1-12 weeks, significantly lowered triglycerides ⁽¹¹⁾

– 1 avocado in a day, signifacantly reduced oxidised LDL (the type linked to artery damage) ⁽⁵⁾

– 1 avocado p/d over 5 weeks significantly Improved LDL particle size (a type of LDL less likely to cause plaque build-up) ⁽¹²⁾

– 1 avocado p/d over 5 weeks significantly Improved lutein (an antioxidant) in the blood ⁽¹³⁾

Other clinical trials have shown that acute consumption of avocado in a single day on 16 healthy young males aged 18-28yrs ⁽¹⁴⁾, significantly improved blood lipid profiles (fig. 4) compared to typical low-fat or moderate-fat diets.

Avocados and other metabolic outcomes
Studies have also investigated the physiological effects of adding avocado to other meals on flow-mediated dilation (FMD). FMD is a non-invasive ultrasound measure of how well an artery widens in response to increased blood flow and is commonly used as an indicator of blood vessel (endothelial) health; greater vasodilation and arterial flexibility generally indicate better vascular function. A multi-arm randomised controlled trial involving healthy young overweight men ⁽⁷⁾, investigated postprandial (after-eating) effects on endothelial health measured by FMD, after the consumption calorie matched diets of various meals by measuring FMD compared to baseline over the course of 4 hours, with 7 days between each meal:

(i) a Hass avocado sandwich with low-fat milk
(ii) a hamburger plus whole milk
(iii) donuts rich in saturated fat vegetable oil milk

The Hass avocado sandwich significantly improved FMD, compared to the poorer FMD measures after consuming the hamburger and donut meals on their own (fig. 5). In a nutshell, food pairing matters.

Another crossover randomised controlled trial in overweight and obese men (n=21) and women (n=18) ⁽¹⁴⁾, also found that compared to a no-avocado, high carbohydrate energy-matched breakfast, an avocado breakfast significantly improved FMD responses (fig. 6) compared to the high carbohydrate control meal (p<0.01), independent of amount, whilst significantly reducing blood glucose and insulin responses. Additionally, the avocado breakfast also significantly lowered concentrations of triglyceride-rich lipoproteins (p=0.02) and increased concentrations of larger ‘good’ HDL particles (p<0.05).

Further, a systematic review and meta-analysis on the effects of avocado consumption on risk factors of cardiovascular diseases, found that although avocado-rich diets showed no significant difference on systolic blood pressure (SBP) compared to a habitual diet (HD) group (MD = -1.21 [-3.10, 0.68], P=0.21), SBP significantly decreased in the avocado group when compared to the low-fat (LF) diet group (MD = -1.71 [-2.21, -1.21], P=0.001). Similar results were observed with regards diastolic blood pressure (DBP), and although DBP remained consistent between the avocado and HD groups (MD = 0.72 [-0.16, 1.60], P=0.11), the avocado group showed a more significant decrease in DBP than the LF diet group (MD = -2.32 [-2.81, -1.82], P=0.0001).

Figure 7 depicts the potential molecular mechanisms appertaining to the different dietary compounds present in Hass avocado, such as antioxidants, fibre and MUFA, and their potential beneficial effects on CVD prevention and control ⁽²⁸⁾.

Other evidenced health benefits
Diets that include avocados tend to contain more unsaturated fats than saturated fats, a balance that supports heart health ⁽⁶⁾, weight management ⁽¹⁴⁾, and brain function ⁽¹⁶⁾. This type of fat ratio fits well with UK ⁽²⁶⁾ and USA ⁽²⁷⁾ dietary recommendations, which encourages replacing saturated fats with unsaturated fats to help maintain healthy cholesterol levels and reduce the risk of CVD.

As discussed earlier, a large portion (71%) of the fats in avocado are in the form of MUFAs. Higher MUFA intake have been associated with an overall risk reduction in cardiovascular mortality (12%), all-cause mortality (11%), stroke (17%), and cardiovascular events (9%), compared to lower MUFA intakes ⁽¹⁵⁾. Avocados are also rich in oleic acid, a type of MUFA also present in olive oil, that may help improve feelings of fullness and reduce fat storage compared with diets higher in saturated fats, reducing caloric intake and supporting weight loss, as evidenced in a Systematic Review of human clinical trials ⁽¹⁵⁾. Quick pause: have you considered my WEIGHT LOSS & DETOX programme?

Other human clinical trials have showed that diets higher in avocados ⁽¹⁶⁾, led to improved brain function, improved blood flow to the brain, improved concentration and long-term cognitive health. Therefore, it may be entirely possible that MUFAs may be responsible for the beneficial health outcomes. Figure 8 depicts an overview of the potential health benefits of avocado consumption on a number of health outcomes published in the literature.

Avocados and weight loss
UK ⁽¹⁷⁾ and European diet ⁽¹⁸⁾ surveys show that the average Western diet contains about 1.6–1.7 calories per gram of food contrbuting to increaswed weight gain ⁽²⁰⁾. This is typical of diets that are lower in fruit and vegetables and higher in processed foods, which can increase overall calorie intake. Studies have found that diets with higher energy density are linked to gradual weight gain and more abdominal fat over time. In contrast, foods with lower energy density provide more volume for fewer calories, helping people feel fuller and manage their weight ⁽²¹⁾.

For example, most fresh fruits have a very low energy density (around 0.3–1.0 kcal/g) ⁽¹⁹⁾, meaning you can eat larger portions without consuming too many calories. Avocados have a moderate energy density (about 1.6 kcal/g), similar to the average Western diet, but they also contain more fibre, water, and beneficial nutrients that help increase satiety (fullness), which studies suggest can help reduce snacking and overall calorie intake during the day. Supporting this idea, a recent human clinical trial found that people eating minimally processed foods lost more weight and body fat than those eating ultra-processed foods, even when both diets contained the same number of calories. Those eating minimally processsed foods also reported reported a two-fold greater improvement in overall craving control, a four-fold greater improvement in craving control for savoury food, and an almost two-fold greater improvement in resisting whichever food they most craved.

Overall, this evidence suggests that not all calories affect the body in the same way. Foods with similar calorie levels can have very different effects on hunger and health depending on their nutrients and how processed they are. Choosing nutrient-rich, filling foods such as fruits, vegetables, and foods like avocado, instead of highly processed foods high in fat, salt, and sugar, may help people feel fuller, snack less, and maintain a healthier weight.

As a case in point, a large prospective study ⁽¹²⁾ found that persons who consumed avocados daily (≥32g p/day) who were normal weight at baseline, increased weight at a slower rate (0.26%) compared to non-avocado consumers (0.79%). High Hass avocado consumers were also shown to have modest, but significantly lower body weight and body mass index (BMI) than non-consumers (fig. 9)

Other clinical trials appear to support the benefit of consuming avocados on weight loss. A parallel randomised controlled trial of 51 healthy overweight or obese adults (78% women, mean age 39 years, mean BMI 30, mean body fat 40%), randomised to calorie-matched diets both with a ~500 kcal deficit, with and without a daily Hass avocado for 12 weeks ⁽²³⁾, suggested that there were no statistically significant differences in change of body weight (figures 10), BMI, total fat (%), or visceral fat (fig. 11) between the two diets.

What this means is that the addition of avocado to a calorie deficit did not affect the ability to lose weight any more than a calorie-reduced diet without the inclusion of avocado, dispelling a common assumption that avocados are too fatty or too calorific, and that adding them may hamper weight loss goals, this is simply not supported by the literature. Another finding in that same study, was that the avocado diet had a small, but significantly higher satiety score (0.26, p<0.05) compared to the control diet, which appears to support the evidence discussed earlier that avocados may help reduce calorie intake by increasing satiety, hence, further supporting the argument that not all calories are made equal.

The key take-home points are that, 1) you can loose weight in many ways, but the key factor is how that weight loss was achieved and the importance of loosing subcutaneous and visceral fat, but not at the expense of fat-free mass (muscle and bone), and, 2) look beyond the calories and the nutritional information on a food label. Quick pause: Work with a highly qualified professional like myself, and consider my WEIGHT LOSS & DETOX programme

Avocados and inflammation
With regards inflammation, an interesting crossover randomised controlled trial investigated the 2-hour postprandial effects of the addition of half a fresh avocado (68 g) to a 250g hamburger patty (fig. 11) and the effects on FMD and inflammation in eleven male subjects (mean age 25 years, mean BMI 24 kg/m2) ⁽²⁴⁾.

Remarkably, the addition of half an avocado to a hamburger patty prevented the reduction in vasodilation associated with eating hamburgers alone (fig. 12). Additionally, adding the avocado to the hamburger meal, reduced systemic inflammation by:

(i) significantly preserving I-kappa B alpha activity (I-NfkBa), a well recognised regulator of inflammation response, (131% vs. 58%, p = 0.03) compared to eating the hamburger alone after 3 hours.

(ii) avocado plus the hamburger blocked a significant increase in serum Interleukin-6 (IL-6), an inflammatory cytokine, compared to the hamburger alone over 4 hours.

Let’s briefly take a step back and look at how avocado compounds may help fight inflammation. With regards to point (I) above, the image below provides a visual representation of how the compounds found in avocados may help reduce inflammation. The key mechanism is by modulating the expression of the Nuclear factor-kappa Beta (NF-κB) signalling pathway (fig. 13). NF-κB is a transcription factor that regulates the expression of many downstream inflammatory mediators, such as IL-6 (cf: point [ii] above) ⁽²⁵⁾. Hass avocado-derived phytochemicals appear to inhibit the activation of NF-κB partly by stabilising it’s inhibitor I-NfkBa, which helps down-regulate NF-κB ⁽²⁴⁾. Reducing the inflammatory cascade is critical to attenuating the inflammatory responses driving many present day chronic diseases, such as:

• Metabolic syndrome
• Cardiovascular disease
• Arthritic diseases
• Inflammatory bowel disease
• Neuroinflammation, and more.

Because of the involvement of NF-κB in the pathophysiology of many chronic diseases, NF-κB has become a major pharmacological target for anti-inflammatory drugs.

What are the limitations?
Do all the studies investigating the addition of avocado to various diets lead to beneficial outcomes? Although no major adverse effects were observed, some studies did not observe any benefit to adding avocado to a low-fat vegetarian diet on high-cholesterol participants ⁽¹⁰⁾, whilst another randomised clinical trial showed no effects of consuming 1 avocado p/d over 6 months on FMD compared to a controlled diet consuming less than 2 avocados per month ⁽²⁾. Other limitations are that:

(i) many of the clinical trials were relatively short in duration composed of a small number of participants;

(ii) the clinical trials or observational studies were not assessed for quality, statistical analysis of mean effects, or study variations (heterogeneity) to support each of the purported health effects, so caution is warranted and further research is required to determine the veracity of the findings.

(iii) It also remains uncertain whether other avocado varieties may reproduce the purported health benefits of the Hass.

However, given the amount of research discussed supporting the safety and benefit of consuming at least one avocado per day for varying amounts of time, the inclusion of avocado in every day diets may be a safe and justified addition for most individuals.

Adverse effects of consuming avocados
Avocados can be a nutritious addition to many diets, but they may not be suitable for everyone. Because of the other food components present in avocado which I will not go in to, some individuals may find that avocados do not agree with them due to digestive sensitivity, individual metabolic responses, or specific dietary requirements. In certain cases, people with particular health conditions or sensitivities may need to limit or avoid them at least temporarily, and so food choices often need to be considered on an individual basis rather than assuming that any single food is universally beneficial or detrimental. This is how evidence-based personalised nutrition works and part of what I practice.

How to buy and eat avocados
Choose avocados that feel slightly soft when gently pressed, but not mushy, as this usually indicates they are ripe and ready to eat; firmer avocados can be left to ripen at room temperature for a few days, while ripe ones can be stored in the fridge to slow further softening. To prepare, cut the avocado lengthwise around the stone, twist the halves apart, remove the stone, and scoop out the flesh or slice it while still in the skin. Avocados can be eaten on their own or added to salads, sandwiches, smoothies, or savoury meals, and a squeeze of lemon or lime juice can help slow browning once cut (fig. 13).

Let’s work together
I am confident you have enjoyed this blog post, if so please SUBSCRIBE to my monthly newsletters. There is more I could say about avocados, so if you are interested in learning more about the topic or other foods, understand whether avocado or any other food for that matter may be suitable for you or not, if you wish to address a health concern, a symptom, or simply optimise your diet, get in touch to work with me. You can also consider my WEIGHT LOSS & DETOX programme.

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