Consumption of Avocados May Reduce Adult Weight Gain but Depend on Initial Body Mass Index
Avocados (Persea americana, Lauraceae) are nutrient-dense and medium-caloric food. They provide dietary fiber, phytochemicals, mannoheptulose, and monounsaturated fatty acids (MUFAs). In vivo studies indicate an association between lower body weight and avocado consumption. However, according to the authors, very few studies have examined the relationship between avocado intake and adiposity in humans, with inconsistent results. The authors state that no large epidemiological studies have evaluated the longitudinal relationship between avocado intake and changes in weight or obesity risk. Hence, the purpose of this longitudinal registry study was to examine the effect of habitual avocado intake on adult weight gain and changes in body mass index (BMI).
This analysis uses the Adventist Health Study-2 (AHS-2) cohort. The full cohort comprises approximately 96,000 people of which approximately 65% are women and 27% are African American. The participants lived in the United States or Canada at the time of enrollment. The full cohort is unique because the participants have a very low rate of smoking (1.1%) and alcohol consumption (6.6%). The AHS-2 study enrolled participants from February 2002 to December 2007. Included participants were proficient in English, ≥ 30 years old, and completed a comprehensive lifestyle questionnaire. The baseline questionnaire collected self-reported height, weight, birth date, gender, ethnicity, health history, education, physical activity, use of tobacco, and typical dietary intake. The collection of follow-up data is ongoing. The comprehensive lifestyle questionnaire included a 204-item quantitative food frequency questionnaire (FFQ) to assess dietary intake, including avocado. Regarding avocado intake, participants were queried about the average frequency and amount of avocado and/or guacamole consumed in the last year. Choices for frequency included “never or rarely,” “one to three times per month,” “one time per week,” “two to four times per week,” “five to six times per week,” “one time per day,” and “two or more times per day.”
Choices for serving sizes included a standard serving (one-fourth of a medium-sized avocado or one-fourth cup of avocado or guacamole); less than one-half of the standard serving; and greater than or equal to one and half of the standard serving. The study considered the standard size avocado to be 32.02 g. Daily avocado intake (g/day) was calculated, and consumption was categorized into either consumer versus non-consumers or non-consumers versus low consumers (>0 to <32 g/day) versus high consumers (≥32 g/day). Total energy intake and dietary patterns were evaluated, and BMI was calculated. For the purposes of this study, participants excluded from the analysis had a calculated energy consumption of <2092 kilojoule (KJ) or >18,828 KJ per day; baseline BMI <18 kg/m2 or >40 kg/m2; were pregnant at baseline; were currently smoking; had implausible anthropometric values or changes; women with a height <142 cm or >183 cm, and men with a height <152 cm or >198 cm; had missing questionnaire return dates; had missing avocado data; and were missing data for gender, race, age, education level, physical activity, sedentary time, and dietary patterns. Daily avocado intake was adjusted for total energy intake. Covariates were identified and included in the analysis. Follow-up weight was collected 4-11 years after baseline.
In total, 55,407 participants (mean age 55.9 years) met the inclusion/exclusion criteria. Of these, 23,242 were non-consumers of avocado, 31,346 were low consumers, and 819 were high consumers. The high consumers had the greatest daily caloric intake. Non-consumers were significantly more sedentary, had significantly less vigorous activity/day, had significantly greater weight, and significantly greater BMI than avocado consumers (P < 0.0001 for all). Greater avocado intake was associated with a less sedentary lifestyle, more vigorous daily activity, lower weight, and lower BMI. Among participants who were normal weight at baseline, 17% became overweight/obese. Normal weight non-consumers were significantly more likely to become overweight/obese (P < 0.0001). Overweight/obese consumers were significantly more likely to become normal weight (P = 0.004). Among normal-weight participants, avocado consumers had a lower rate of weight and BMI increase. Older people tend to lose weight over time. Avocado consumers ≥60 years old had less tendency to lose weight and BMI over time compared with non-consumers. The findings did not change after adjusting for follow-up time, energy intake, gender, race, age, education, physical activity, sedentary time, and dietary patterns.
The authors conclude that among avocado consumers in this cohort, “there was a reduction in the odds of becoming overweight/obese compared to those who did not eat avocado, but this finding was attenuated by adjusting for baseline BMI. Differences in baseline BMI had more of an impact on the odds of becoming overweight/obese than differences in avocado intake.” They conclude that among participants who had a normal BMI at baseline, avocado consumers gained less weight and BMI over time than non-consumers, but the differences were small. The effect of avocado consumption in elderly people may be an important finding that deserves additional exploration. The strengths of the study are a large size and longitudinal analysis. It should be noted the population did not smoke or drink alcohol, which eliminates covariates but decreases the generalizability to the overall population. An important limitation of the study is that avocado intake was only measured at baseline, and the consumption patterns were assumed to not change over time. Therefore, a direct correlation between avocado consumption and weight/BMI cannot be ascertained.
Heskey C, Oda K, Sabaté J. Avocado intake, and longitudinal weight and body mass index changes in an adult cohort. Nutrients. 2019, 11, 691; doi:10.3390/nu11030691.