June 2016 Issue

Hottest Nutrition Trends of 2016: Avocado Spotlight
By Jessica Fishman Levinson, MS, RDN, CDN
Today's Dietitian
Vol. 18 No. 6 P. 42

This creamy fruit is in high demand among consumers due to its health benefits and culinary versatility.

Avocados are near the top of the list of the hottest nutrition trends of 2016. While they've been most commonly used to make guacamole, this creamy fruit is now being used as a sandwich spread and salad topper, a substitute for butter in baked goods, an ingredient in smoothies and ice cream, and the trendiest use of all—avocado toast.

Between 2012 and 2014, retail sales of avocados increased 28%, with Hass avocados in particular accounting for 94% of sales.1

Greater consumer demand for avocados comes at a time when people are becoming less afraid of eating high-fat foods and the fruit is more available at supermarkets year-round. Today's Dietitian takes a look at how avocados have gained in popularity, why they're so healthful, and how consumers can put them to use in the kitchen.

Botany and Brief History
The avocado (Persea americana) is originally from south-central Mexico, dating back at least 10,000 years. Avocado trees are part of the flowering plant family Lauraceae along with cinnamon, camphor, and bay laurel. Botanically, the avocado fruit is a large berry with a single seed. Researchers believe that humans began cultivating avocados around 5,000 BC. In the 16th century, Spanish explorers were the first Europeans to eat avocados, or aguacate, as they're called in Spanish. At the time of the Spanish Conquest, avocados made their way from Mexico through Central America into parts of South America. Slowly, avocados became popular and new varieties were found, including Guatamalan, Mexican, and West Indian. It was on the tropical island of Barbados in 1751 when George Washington found and ate avocados, later writing that "agovago pears" were abundant and popular.

In 1833, the first avocado tree was planted in America in Florida, followed by Los Angeles in 1856, and in other southern California locations thereafter. In 1926, the first Hass avocado tree was planted in California, and to this day Hass avocados are the most popular California avocados, unique in that they're produced year-round. Nonetheless, Mexico is still the top producer of the world's avocados.

Avocados grow in a two-year cycle, with the amount of fruit harvested dependent on the weather and cultural management from the preceding two years. They mature on the tree but are picked when they're hard, and they ripen once off the tree within one to two weeks at room temperature. Some supermarkets sell ripe avocados, which have been treated with synthetic ethylene gas in a "ripening room" to speed up the ripening process.

Health Benefits
Part of what drives the popularity of avocados is the fact that they're nutrient dense, with nearly 20 vitamins, minerals, and phytonutrients. A 1-oz serving of avocado (about one-fifth of a medium avocado) contains 50 kcal, 4.5 g fat, 0.5 g saturated fat, 3 g monounsaturated fat, and 2 g dietary fiber. Thanks to their high fat content, avocados help the body absorb fat-soluble nutrients like vitamin A when eaten together. Vitamin A is known for its important role in eyesight, as are the phytonutrients lutein and zeaxanthin, which can't be synthesized by the body but are found in avocados. Studies show that lutein and zeaxanthin are linked to reduced risk of cataracts and macular degeneration, which are common in the aging population.2,3

In addition to the eye health benefits of avocados, the fruit has been shown to have heart-health properties. Although high in fat, avocados contain healthful monounsaturated fats and phytosterols, plant sterols that compete with cholesterol for absorption. Scientific research shows that these healthful fats and phytosterols have a cholesterol-lowering effect when substituted for sources of saturated fat.4 Moreover, there's some promising research showing that avocados may reduce markers of inflammation, which is a risk factor associated with heart disease. A 2013 study found that when participants ate fresh avocado with a lean beef burger, the production of interleukin-6, a marker of inflammation, was neutralized, and there was no increase in triglyceride levels compared with when they ate the burger alone5—a good reason to add guacamole to a burger this barbecue season.

One of the metabolic effects of eating high-fat foods is their satiety factor and the role they play in blood sugar stabilization, especially in people with diabetes. A 2013 pilot study conducted at Loma Linda University looked at these effects when avocados were incorporated into a lunch meal. Results showed that the addition of avocado at lunch led to a significant decrease in the desire to eat after the meal was completed and a significant increase in self-reported satisfaction over a three-hour period following the meal. Researchers also found that including avocado at lunch helped mitigate insulin spikes 30 minutes after the meal, regardless of whether the avocado was eaten in addition to the rest of the meal or replaced part of the meal. When the avocado replaced part of the meal, blood insulin remained significantly lower over a three-hour period, but this didn't hold true when the avocado was added to the meal. The researchers concluded that more research is needed to determine the effect of avocado on satiety and insulin response.6

Kitchen Uses
When purchasing avocados, unless you plan to serve them immediately, look for hard, unripened fruit with light green skin. The Hass Avocado Board recommends purchasing unripe, firm green avocados four to five days ahead of when you need to use them and storing the fruit at room temperature. Avocados usually turn from light green to dark green to black when ripening, but some varieties don't change color, so you can't rely on color alone to determine if the fruit is ripe. Instead, gently squeeze the avocado in the palm of your hand to check for ripeness. Ripe, ready-to-eat fruit will be firm yet yield to gentle pressure.

Once ripened, use avocados immediately or store them in the refrigerator for two to three days. Cut avocado can be stored in the refrigerator, but to prevent browning from oxidation, sprinkle it with lemon or lime juice and wrap it in plastic wrap, or store it in an air-tight container. If the outer layer turns brown or black during storage, skim the layer and discard.

The easiest way to prepare an avocado is to cut down the center lengthwise around the seed and then hold the avocado in the palm of one hand while using the other hand to twist the halves apart. To remove the seed, slip a spoon between the seed and fruit and gently work the seed out of the fruit.

A recent popular trend that has gone viral on the Internet involves roasting and dicing the avocado seed, then grinding it to powder in a blender to add to smoothies and other recipes, based on the assumption that the seed provides up to 70% of the nutritional value of the avocado. Research on the health benefits of avocado seeds is limited to the extracts of the avocado seed, not ground seeds, which is what the trend suggests.7 The California Avocado Commission doesn't recommend eating ground avocado seeds and questions the safety of doing so.

While it's not recommended to eat the avocado seed, there are plenty of ways to enjoy the avocado flesh, starting with eating it on its own. Avocados come in a self-contained bowl—all you have to do is sprinkle the flesh with some lime juice and coarse salt, then dive in with a spoon and enjoy. Other ways to use avocados are in spreads, dips, cubed, or sliced in a salad or on a sandwich, stuffed, in dressings or marinades, blended into soups and smoothies, swapped for mayonnaise in chicken or egg salad, used in place of some oil or butter in baked goods, and more. The possibilities are endless.

— Jessica Fishman Levinson, MS, RDN, CDN, is a New York-based nutrition consultant, writer, and recipe developer, and the founder of Nutritioulicious (www.nutritioulicious.com).

References
1. Hass Avocado Board. 2014 state of the category. http://www.hassavocadoboard.com/sites/default/files/hab-state-of-category2014.pdf

2. Gale CR, Hall NF, Phillips DI, Martyn CN. Lutein and zeaxanthin status and risk of age-related macular degeneration. Invest Ophthalmol Vis Sci. 2003;44(6):2461-2465.

3. Delcourt C, Carrière I, Delage M, Barberger-Gateau P, Schalch W. Plasma lutein and zeaxanthin and other carotenoids as modifiable risk factors for age-related maculopathy and cataract: the POLA Study. Invest Ophthalmol Vis Sci. 2006;47(6):2329-2335.

4. Peou S, Milliard-Hasting B, Shah SA. Impact of avocado-enriched diets on plasma lipoproteins: a meta-analysis. J Clin Lipidol. 2016;10(1):161-171.

5. Li Z, Wong A, Henning SM, et al. Hass avocado modulates postprandial vascular reactivity and postprandial inflammatory responses to a hamburger meal in healthy volunteers. Food Funct. 2013;4(3):384-391.

6. Wien M, Haddad E, Oda K, Sabaté J. A randomized 3x3 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;12:155.

7. Oboh G, Odubanjo VO, Bello F, et al. Aqueous extracts of avocado pear (Persea americana Mill.) leaves and seeds exhibit anti-cholinesterases and antioxidant activities in vitro. J Basic Clin Physiol Pharmacol. 2016;27(2):131-140.

RESOURCES

• Love One Today. Hass Avocado Board (www.avocadocentral.com), an agriculture promotion group that promotes consumption of Hass Avocados in the United States.

• California Avocado Commission (www.californiaavocado.com), the official information source for California Avocados and the California Avocado industry.

• 2015 AvoScore Cards. Hass Avocado Board (www.hassavocadoboard.com/retail)

• A Brief History of the Avocado. AvoSeedo (www.avoseedo.com/a-brief-history-of-the-avocado)