Subtropical Fruit Crops Research & Education
University of California
Subtropical Fruit Crops Research & Education

Posts Tagged: nutrition

Eat THAT Seed??????

We have received a lot of questions from consumers and dietitians lately asking us what we think about consuming the avocado seed/pit. So is it safe to eat the avocado seed? We don't recommend it.

While this is presently a very popular topic and there is a body of evidence looking at extracts of the avocado seed, the fact is there is not enough research to support consuming an avocado seed. The purported health benefits and risks of avocado seed intake are poorly characterized. 

As stated in a 2013 research study by Pennsylvania State University, “although the currently available data is promising, for most indications, it remains very preliminary and further studies are needed” and “In addition, the safety of the various extracts of the avocado seeds must be assessed in order to more fully estimate the usefulness of this resource."

While it is not recommended that you eat the seed of the avocado, the fruit/pulp of the California Avocados is ripe with nutrition. One-fifth of a medium avocado (1 oz.) has 50 calories and contributes nearly 20 vitamins and minerals, making it a tasty choice for a nutritious and healthy diet. California Avocados are naturally sodium and cholesterol-free; a naturally nutritious superfood. 

And some research papers to chew on:

Avocado (Persea americana) seed as a source of bioactive phytochemicals


Nutritional efficacy of avocado seeds


Optimization of the antioxidant and antimicrobial response of the combined effect of nisin and avocado byproducts


Posted on Friday, July 13, 2018 at 6:07 AM
Tags: avocado seeds (1), nutrition (5), peel (2), phytochemicals (1), tannins (1)

Eat More Avocados

MISSION VIEJO, Calif. — Tufts University has released results of a study linking eating avocados to helping improve cognitive brain function in older adults, news especially relevant to Hispanics who have been found to have the longest life expectancy rate in the U.S.1 Published in the journal Nutrients and supported by the USDA and the Hass Avocado Board, the research tracked how 40 healthy adults ages 50 and over who ate one fresh avocado a day for six months experienced a 25% increase in lutein levels in their eyes and significantly improved working memory and problem-solving skills.

Lutein is a type of carotenoid antioxidant, or pigment, commonly found in fruits and vegetables already widely accepted to have a role in preserving eye health and now increasingly thought to have a positive impact on brain health as well. As study participants incorporated one medium avocado into their daily diet, researchers monitored gradual growth in the amount of lutein in their eyes and progressive improvement in cognition skills as measured by tests designed to evaluate memory, processing speed and attention levels. In contrast, the control group which did not eat avocados experienced fewer improvements in cognitive health during the study period.

“The results of this study suggest that the monounsaturated fats, fiber, lutein and other bioactives make avocados particularly effective at enriching neural lutein levels, which may provide benefits for not only eye health, but for brain health,” said Elizabeth Johnson, Ph.D., lead investigator of the study from the Jean Mayer USDA Human Nutrition Research Center on Aging, at Tufts University. “Furthermore, the results of this new research reveal that macular pigment density more than doubled in subjects that consumed fresh avocados, compared to a supplement, as evidenced by my previous published research. Thus, a balanced diet that includes fresh avocados may be an effective strategy for cognitive health.”

“Tuft's findings that eating avocados is linked to a positive impact on memory is one more reason to enjoy healthy avocados daily. It's especially good news for Hispanic households where avocados are already so popular and older generations are culturally central to the core family unit,” said Emiliano Escobedo, Executive Director of the Hass Avocado Board. “More research is needed in different populations with different amounts of avocado to better understand the connection between avocados and brain health.”

To view the abstract, visit here.

This study is part of ongoing research that is continually unlocking the unique benefits of avocados to human health. Discover delicious inspiration for different ways to prepare and enjoy healthy avocados in Spanish at and in English at

1.   Center for Disease Control, April 2016

–The Hass Avocado Board


For Full Article, Click on Download PDF [235 KB, uploaded 23 August 2017]

Nutrients 20179(9), 919; doi:10.3390/nu9090919

Avocado Consumption Increases Macular Pigment Density in Older Adults: A Randomized, Controlled Trial

Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA
Author to whom correspondence should be addressed.
Received: 9 May 2017 / Revised: 17 August 2017 / Accepted: 21 August 2017 / Published: 23 August 2017
Download PDF [235 KB, uploaded 23 August 2017]


Lutein is selectively incorporated into the macula and brain. Lutein levels in the macula (macular pigment; MP) and the brain are related to better cognition. MP density (MPD) is a biomarker of brain lutein. Avocados are a bioavailable source of lutein. This study tests the effects of the intake of avocado on cognition. This was a six-month, randomized, controlled trial. Healthy subjects consumed one avocado (n = 20, 0.5 mg/day lutein, AV) vs. one potato or one cup of chickpeas (n = 20, 0 mg/day lutein, C). Serum lutein, MPD, and cognition were assessed at zero, three, and six months. Primary analyses were conducted according to intent-to-treat principles, with repeated-measures analysis. At six months, AV increased serum lutein levels by 25% from baseline (p = 0.001). C increased by 15% (p = 0.030). At six months, there was an increase in MPD from baseline in AV (p = 0.001) and no increase in C. For both groups, there was an improvement in memory and spatial working memory (p = 0.001; p = 0.032, respectively). For AV only there was improved sustained attention (p = 0.033), and the MPD increase was related to improved working memory and efficiency in approaching a problem (p = 0.036). Dietary recommendations including avocados may be an effective strategy for cognitive health.
Keywords: lutein; avocado; macular pigment; bioavailability; cognition; older adult luteinavocadomacular pigmentbioavailabilitycognitionolder adult
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

avocado fruits
avocado fruits

Posted on Wednesday, August 30, 2017 at 3:00 PM
Tags: avocado (289), fruit (18), helath (1), lutein (1), nutrients (21), nutrition (5)

Citrus Grower Meeting Coming Soon

Every year growers get together to learn what is being done in the citrus research world that could affect their operations. This June, University of California and the Citrus Research Board are bringing some good talks to three different growing areas. All growers are invited, but RSVPs are appreciated.


CRB-GrowerSeminar-Flyer 2017
CRB-GrowerSeminar-Flyer 2017

Posted on Friday, May 19, 2017 at 6:13 AM
Tags: ACP (86), alternate bearing (5), breeding (4), citrus (338), disease (57), fertilizers (6), grapefruit (27), huanglongbing (66), irrigation (79), irrigation (79), lemons (9), mandarins (5), nutrition (5), oranges (6), pests (25), tangerines (1)

New Avocados for the Valley?

California avocados are the best in the world. So says downtown restaurant manager Daniel Avalos in a Valley Public Radio story by reporter Ezra David Romero.

The fact that they currently thrive only on a small swath of coastal Southern California is being challenged by UC Cooperative Extension specialist Mary Lu Arpaia. She is on a mission to find avocado varieties that withstand the hot summers and cold winters of the San Joaquin Valley, where irrigation water and crop land are more abundant and cheaper. 

She hopes to find avocado varieties that ripen at various times of year, and varieties that might be an alternative crop for citrus growers should huanglongbing, a disease that has devastated the Florida citrus crop, take hold in Central California.

"There's a void of California fruit on the market in the months of November, December and actually early January," Arpaia said. "So if we can find different selections that maybe are unique that fit into that window, then we help the entire California avocado industry."

An as-yet unnamed avocado variety. 

Romero visited the UC Lindcove Research and Extension Center to see the trees in Arpaia's study. Currently, the vast majority of California avocados are the Hass variety. The goal is to breed varieties with similar eating quality that grow to a moderate height and have high yield. One potential that is already being produced by nurseries is called "gem."

"This is gem," said Eric Focht, a staff research associate in Arpaia's lab. "You can see it's a little more oval or egg shaped than Hass. It has the speckling on the skin. Now as this ripens, it will turn dark and a lot of times the speckled lenticels with get a yellow kind of golden color it it."

Another promising variety is called "lunchbox" because of its small size. According to Focht, it "just falls out of the skin." Arpaia said, "It makes wonderful guacamole and I found, with a non-replicated test in my refrigerator, the fruit doesn't brown."

Arpaia's favorite guacamole recipe is featured at the end of the story on the KVPR website. And there is more on this story at:


Mary Lu Arpaia

Mary Lu
Mary Lu

Posted on Friday, May 12, 2017 at 5:46 AM
  • Author: Jeanette Warnert
Tags: avocado (289), California (13), citrus (338), freeze (10), frost (19), heat damage (4), irrigation (79), lemon (100), new crops (6), new variety (1), nutrients (21), nutrition (5), oranges (6), temperature control (1)

Do I Really have Virus in my Citrus?

When reviewing possible problems your citrus might have, it's easy to jump to the conclusion that it is a virus.  That's because viruses are a major problem around the world in citrus and the effects can be slow, chronic and debilitating or fast and deadly. Images get posted on the web, and if those symptoms look like something your tree has, then by golly you have a virus.  Well, actually viruses are everywhere and in most plants, so you probably do have a virus or viruses, but not plant debilitating one.  California, has had a pretty thorough nursery inspection procedure in place for many years and the likelihood of a virus causing a problem is less likely here than in many parts of the world.

 In most cases viruses are difficult to eradicate in practice, so it is best to remove them before they get out in the field.  The Citrus Clonal Protection Program ( weeds out citrus viruses before they get to wholesale nurseries and into the trade.  That does not mean that we don‘t have debilitating viruses in the California industry.  We do.  Tristeza is in some of our orange orchards and that can lead to significant yield reductions and tree death (  Tristeza is spread by the melon aphid and is hard to control without good control of the aphid.  In many older orchards there is exocortis and psorosis;  These are graft transmissible and why it is not good, in fact unlawful, to propagate trees with uncertified budwood.

In most cases in California if you are having symptoms of unhealthy in your trees it's most likely due to an irrigation problem (too much, too little, poor timing), a nutrient deficiency and possibly a fungal disease (most likely a root one such as armillaria or Phytophthora).  Or in this day, it could be the start of Huanglongbing vectored by Asian Citrus Psyllid (  Before jumping to the conclusion that there is a virus in your trees.  Check out the most common problems for California citrus first (  There are enough of those anyway.


Boron toxicity

boron toxicity citrus 1
boron toxicity citrus 1

Posted on Monday, September 14, 2015 at 6:46 AM
Tags: citrus (338), disease (57), health (4), irrigation (79), nutrition (5), virus (5)
Webmaster Email: