Avocados are relatively high in plant sterols — naturally occurring compounds that may have several health benefits — but there does not appear to be quality research regarding their ability to balance hormones, such as relieving the effects of menopause, regulating periods or managing insulin.
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"Plant sterols are very important, and a lot of plants do have selective estrogen receptor modulator (SERM) properties, but I don't think there is any good evidence to show that avocados have a hormone-balancing effect," says Margaret Nachtigall, MD, a reproductive endocrinologist with NYU Langone Health in New York City.
Plant Sterols and Avocados
Phytosterols, known as plant sterols and stanol esters, are compounds found in plant cell membranes, according to the Cleveland Clinic. They can block cholesterol absorption in the body, resulting in reduced blood cholesterol levels.
According to a February 2014 study in Atherosclerosis, avocados are relatively high in plant sterols, containing 75 milligrams of the compound per 100 grams of the fruit (mg/100 g). For reference, oranges contain 24 mg/100 g and broccoli contains 39 mg/100 g.
Plant sterols have been studied in various ways. They are among the few compounds approved for their cholesterol-lowering properties by the European Commission and the Food & Drug Administration (FDA), according to a December 2017 study in Nutrients. The FDA has said that a health claim can be made on food labels that "diets that include plant sterol/stanol esters 'may' or 'might' reduce the risk of heart disease."
According to a July 2014 British Journal of Nutrition meta-analysis, plant sterols and stanols have been proven to have an effect on lowering "bad" low-density lipoprotein (LDL) cholesterol. Adding 2 grams of plant sterol to your diet each day could help lower LDL by 5 to 15 percent, according to the Mayo Clinic.
Selective Estrogen Receptor Modulators (SERMs)
The human body is host to estrogen receptors just about everywhere, Dr. Nachtigall says. "When these estrogen receptors are not being bound because people are not producing adequate estrogen, they can experience many side effects, such as hot flashes, mood changes, trouble sleeping and changes in their menstrual cycle," she says.
Some SERMs bind to some estrogen receptors positively and to others negatively, she explains. "For example, Tamoxifen, a drug used in the treatment and prevention of breast cancer, binds negatively to estrogen receptors in the breast, which has a protective effect; in the uterus, however, it acts like estrogen production [and] can increase endometrial thickness."
Plant sterols tend to behave in a similar manner. "Some of them act like estrogen in some tissues, but have anti-estrogenic effects in others. In soy extracts, one compound that has been studied in cell culture and is sold over the counter, Femarelle, inhibits estrogen in breast cells, but promotes it in bone," Dr. Nachtigall says.
Natural Hormone Balance?
While hormone therapy is an attractive option for some people, others would choose to avoid it; Dr. Nachtigall fields lots of questions from patients interested in natural, dietary alternatives.
"The idea that plant sterols in avocados and other foods would act like SERMs, behaving positively in tissue where it would be beneficial in terms of sleep, mood and bone health, but perhaps negatively in breast tissue, is an attractive concept," she says.
But the amount of sterols people consume in food is relatively low, less than the 2 to 3 grams the National Heart Foundation of Australia recommends for people with high blood cholesterol to take to lower their cholesterol. Supplements with plant sterols may contain higher concentrations, but they raise other concerns, Dr. Nachtigall says.
"Usually, plant sterols are delivered as an extraction with other ingredients and sold over the counter. You have to wonder about the method of extraction and other components of the supplement, because these products are not regulated by the American Food and Drug Administration, so in many instances you don't know what's included," she says.
Hormone balance is a complicated and nuanced topic. "Many people ask what the ideal diet is to maintain hormone balance, but what's right for one person might not be right for another. Everyone is a little different," Dr. Nachtigall says.
The bottom line: Although it may be tempting to credit avocados with hormone-balancing properties due to their high plant sterol content, evidence to support this is lacking.
- Cleveland Clinic: “Boost Your Cholesterol-Lowering Potential With Phytosterols”
- Atherosclerosis: “Plant Sterols and Plant Stanols in the Management of Dyslipidaemia and Prevention of Cardiovascular Disease”
- National Heart Foundation of Australia: “Phytosterol/Stanol Enriched Foods”
- Nutrients: “Plant-Based Beverages as Good Sources of Free and Glycosidic Plant Sterols”
- Margaret Nachtigall, MD, reproductive endocrinologist, NYU Langone Health, New York, New York
- U.S. Food & Drug Administration: “CFR - Code of Federal Regulations Title 21”
- British Journal of Nutrition: “LDL-Cholesterol-Lowering Effect of Plant Sterols and Stanols Across Different Dose Ranges: A Meta-Analysis of Randomised Controlled Studies”
- Mayo Clinic: “Cholesterol: Top Foods To Improve Your Numbers”