Research on Avocados: I’m In!

Summary New research shows that avocados increase beta-carotene absorption and conversion to vitamin A while not increasing caloric intake when eaten in moderate amounts.

Two recent studies on avocados have made this dietitian start eating more.

The first was conducted at Ohio State University and examined whether eating avocado could increase vitamin A levels in the blood after meals (1).

Vitamin A is obtained from plant foods by eating carotenoids which the body can then convert into vitamin A. There is evidence that adding fat to meals can increase carotenoid absorption, which isn’t surprising given that carotenoids are fat-soluble. (See the VeganHealth.org article about Vitamin A for more info.)

The study showed that not only did adding 1/2 of an avocado to a high-carotenoid meal increase the amount of carotenoids absorbed, it also increased the amount of vitamin A in the blood by about 3 to 6 times compared to a high-carotenoid meal without avocado.

Some caveats:

– It’s not clear that the amount of vitamin A measured in the blood after a meal really indicates that someone has better vitamin A status.

– Some people are, apparently, “non-responders” and do not absorb more carotenoids when added to the diet. In this study, one participant (out of twelve) was found to be a non-responder and she was removed.

– The Hass Avocado Board provided some of the support for this study.

Increasing vitamin A isn’t necessarily needed by most people, but since vegans do not get a direct source of vitamin A, and many may not eat enough carotenoids, adding avocado to meals will help ensure that you’re efficiently utilizing carotenoids.

And why not? Avocados are delicious.

Of course, there is a reason why not – because avocados are high in fat.

It turns out that due to their high water and fiber content, avocados barely rise to the category of a medium energy dense food. A serving size is considered 1/2 of a medium-sized avocado or 70 g. One serving contains 4.6 g of fiber, 10 g of fat, but only 112 calories. As an extra bonus, it contains 340 mg of potassium (almost as much as a medium-sized banana).

This brings us to the second study, from Loma Linda University, looking at energy intake and satiety (feeling satisfied) when avocados are added to the diet (2).

There were three test meals: a control lunch without avocado, a lunch with the same amount of calories as the control lunch and including 1/2 of an avocado, and a control lunch plus 1/2 of an avocado.

The lunches with the avocados resulted in slightly less hunger over the next three hours, and the people who ate avocados with lunch ate less calories for their evening meal and snack (1194 vs. 1276 kcal; difference was not statistically significant). The meals in which avocado replaced other calories were the winners as those people ate 83 calories less for the day.

Again, there are caveats:

– This doesn’t mean that eating an avocado every day will lead to weight loss. At the very least, it’s evidence that adding one-half of an avocado a day won’t lead to eating more calories for most people.

– In the words of the authors, “The funding for this study was supported by a grant from the Hass Avocado Board, which had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review or approval of the manuscript.”

Any time a study is supported by an industry group you have to be more skeptical. Even if the Hass Avocado Board had nothing to do with conducting the study, there may be an unconscious bias for a positive analysis. In this case, the Loma Linda University researchers suggest that a longer trial is needed “to evaluate the effects of daily avocado intake on measures of appetite sensation and weight management in free-living normal weight, overweight and obese adults.” In other words, it would be great if the Hass Avocado Board could fund some more research.

But that said, who else is going to fund studies like these? We might have to wait a long time before the government makes studying avocados a priority.

When I go to Chipotle, which is every few weeks, I normally ask them to really limit the guacamole they add. It can be comical how large the servings there get as ingredients pile up and by the time they get to the last item, the guacamole, there is already a massive amount of food on the tray, so I’m not inclined to change my ordering habits there.

But Chipotle aside, the research above has already made me add more avocado to my daily eating habits. Congratulations to the Hass Avocado Board – you’ve made a believer out of me!

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References

1. Kopec RE, Cooperstone JL, Schweiggert RM, Young GS, Harrison EH, Francis DM, Clinton SK, Schwartz SJ. Avocado Consumption Enhances Human Postprandial Provitamin A Absorption and Conversion from a Novel High-β-Carotene Tomato Sauce and from Carrots. J Nutr. 2014 Aug;144(8):1158-66. | link

2. Wien M, Haddad E, Oda K, Sabaté J. A randomized 3×3 crossover study to evaluate the effect of Hass avocado intake on post-ingestive satiety, glucose and insulin levels, and subsequent energy intake in overweight adults. Nutr J. 2013 Nov 27;12:155. | link

9 Responses to “Research on Avocados: I’m In!”

  1. Richard Says:

    Awesome news! Avocados are one of my favorite foods and I eat avocado pretty much every day. I never thought to combine it with carotenoid-rich food, but I’ll have to give that a try.

  2. Derek Says:

    I actually pay Taco Bell for extra guac. I can’t imagine telling Chipotle to limit it.

  3. X-tine Says:

    Jack: What do you make of Dr. Greger’s posts on the potential genotoxicity of avocados? I, too, used to eat avocados regularly, but his posts made me cut back quite a bit.

  4. Jack Norris RD Says:

    X-tine,

    The only data on humans eating avocados, versus in vitro studies, that I found on Dr. Greger’s site was associated with less prostate cancer:

    http://nutritionfacts.org/questions/any-update-on-the-scary-in-vitro-avocado-data/

    I usually do not get too excited about positive results, or worried about negative results, from in vitro studies using foods that have been generally recognized as safe for generations.

  5. Nancy T Says:

    Thanks for the good news! I will continue eating lots of avocado.

  6. Andrea Says:

    I’ve found that the majority of avocados from Mexico contain very little fat if any at all while avocdos from California tend to be very fatty! Especially organic avocados… Love em!

  7. Lori Says:

    Thanks for the avocado article, Jack. I usually have one around to add to my green smoothie, usually putting a third in the smoothie. Really puts the s-m-o-o-t-h in the smoothie, too.

  8. mpe Says:

    Hi
    Just wondering about why tomatoes are left out of your Vit.A article and only mentioned in the study reference #1
    0.5cup is 29 RAE ,higher than a raw apricot,Are the carotenoids not well absorbed in this common food?
    https://ndb.nal.usda.gov/ndb/foods/show/3497?fgcd=&manu=&lfacet=&format=&count=&max=50&offset=&sort=default&order=asc&qlookup=tomato+cooked&ds=

  9. Jack Norris RD Says:

    mpe–

    I leave out tomatoes because they’re not very high in RAE. The reason I include apricots is because they are a yellow-orange color and I want people to know they are also not high in RAE. I can see why this would be confusing.

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