Here in California, avocados are very popular. We put avocado or guacamole on just about everything we eat! We also find creative ways to eat avocados: avocado fries (fried slices of avocado), avocado sour cream, avocado smoothies and soup, and now avocado toast! There are a few cafes in San Francisco where you can buy avocado toast for $5 a pop, but it’s easy to make yourself. Avocado toast is not only a delicious and easy snack, but avocados are packed with many cancer-fighting compounds, which we will evaluate below.
Overall Healthy Ingredient Profile
Here’s a little known fact: Avocados, believe it or not, are a single-seeded berry. Some mistake it for a vegetable because it doesn’t have a particularly sweet taste. Luckily, because of this lack of sweetness, they contain less than a gram of sugar. So, you can easily get your daily dose of fruit without all the sugar!
Avocados are high in phytochemicals and nutrients and low in calories, sodium, and bad fats. According to Natural Health 365, avocados are rich in many vitamins and vital compounds such as potassium (60% more than bananas), vitamin B, vitamin K, and fiber (highest of any fruit; 75% insoluble, 25% soluble). Other important vitamins and minerals include boron, calcium, copper, magnesium, vitamin E, vitamin B6, folate, and pantothenic acid.
They are high in fat, but it’s mostly monounsaturated fat (oleic acid), the compound in olive oil that helps to lower your blood pressure. Along with that, phytosterols, or phytochemicals found in avocados, have cholesterol-lowering properties.
The combination of oils in avocados helps in the absorption of fat-soluble vitamins and phytochemicals. Avocados contain carotenoids, and because they are high in fat, the body is able to absorb these carotenoids quickly. They can also help you process carotenoids from other sources such as leafy salad greens. So, don’t forget to top your salad with a few slices!
The darker green flesh underneath the avocados skin contains high concentrations of antioxidants and phytosterols as well, which helps to reduce inflammation in the body. Phytosterols have been studied in cell and animal models for cancer prevention (see this review and skin cancer prevention article). So, be sure to really scrape the inside of the skin to get the best out of your avocado!
Evidence for Cancer Prevention of Avocados
Prostate, head, neck, colon, and oral cancers
Avocados are high in lutein, zeaxanthin, alpha-carotene, and beta-carotene. These are carotenoids that aid in the prevention of prostate, head, neck, and oral cancers. The fiber in avocado helps prevent colon cancer.
Women who have a higher amount of lutein in their diets may be at a lower risk for breast cancer. The primary fat in avocados, oleic acid, has been shown to protect against breast cancer as well.
There is still some controversy around the association between dietary total fat and fatty acids intake and risk of breast cancer. Results from this meta-analysis suggested that dietary total fat and fatty acids might be not associated with risk of breast cancer. A lot of this science is up for debate, so though we like to tell you that these studies look promising, the results are not concrete.
There are no clinical trials or animal studies with avocado extracts. However, several studies of avocado extracts with leukemia, esophageal, colon, and oral cancer cells look promising. A 2015 study describes avocatin B, a lipid derived from avocado and identified in a high-throughput cell-based screen. Avocatin B reduced the viability of acute myelogenous leukemia cells by targeting mitochondrial components without affecting healthy leukocytes or leukocyte progenitor stem cells. This study suggests a strategy for selective leukemia cell eradication based on a specific difference in mitochondrial function.
The authors of this study from Iran describe four phyto-extracts of avocado for treatment of patients with esophageal cancer and colon cancer. They noted that the phytoextracts have a much lower toxicity than standard chemotherapeutic agents and significantly slow growth of these cancers.
Avocado extracts have also shown activity against oral cancer cells. This paper discusses how the phytochemicals in avocados arrest cancer cells in their cell division cycle and lead to apoptosis, which is natural cell death.
Other recent studies indicate that phytochemicals extracted with chloroform from avocado fruits target multiple signaling pathways and increase intracellular reactive oxygen leading to apoptosis. This review summarizes the reported phytochemicals in avocado fruit and discusses their molecular mechanisms and targets. These studies suggest that individual and combinations of phytochemicals from the avocado fruit may offer an advantageous dietary strategy in cancer prevention.
Choosing, Peeling, and Storing Avocados
A great explanation on how to choose the right avocado is to select an avocado that, when squeezed, yields to the pressure you apply. In other words, soft, but not squishy. Store your avocados on your counter. Do not put them in the refrigerator! In fact, if your avocados are on the harder side, store them near a window in indirect sunlight or store them in a paper bag to get them to ripen quicker.
The closer you get to the peel, the higher the phytonutrient and antioxidant content. So, many advise that you peel the avocado instead of slice it open and scoop out the insides. If you do it the second way, be sure to scrape the inside of the skin as best you can.
Once an avocado has been opened, reducing the avocado’s exposure to the air will help you keep it fresh for a longer period of time. Some suggest storing it with slices of onion in an air-tight container in the refrigerator.
Avocados are famous for going bad very quickly. You want to avoid eating it after it becomes oxidized (turns brown) or develops any mold. Once the avocado goes bad and turns brown, the inside will become stringy, and nobody wants to eat that!
That said, enjoy our recipe below!