Avocados (Persea americana) generally are considered a healthy food; the high fat content of avocados typically is the only reason given for limiting consumption of this fruit. Avocados are a good source of monounsaturated fats, folate, vitamin B6, and various chlorophylls. Avocados have been shown to protect the liver, improve cholesterol, and ameliorate osteoarthritis symptoms. Avocado extract has been shown to have chemopreventive effects on human oral premalignant and malignant cells, as well as inhibiting the growth of both androgen-dependent and androgen-independent prostate cancer cell lines in the laboratory. Avocados are a rich source of cytochrome P-450s, enzymes involved in drug metabolism and estrogen metabolism, the implications of which for breast cancer have not been established.
Breast cancer-related effects of eating avocados
One study found that a diet high in avocado oil promoted the formation of mammary tumors in rats. Another study of postmenopausal U.S. Latina women found that consumption of avocados was associated with higher circulating estrogen levels. On the other hand, a toxin in avocado leaves has been shown to enhance the cytotoxic effects of tamoxifen on human breast cancer cells regardless of their estrogen receptor (ER) status. Based on the available evidence, breast cancer patients, survivors and those at high risk should limit consumption of avocados until further studies clarify these findings.
Lactating animals that gain access to avocado leaves or fruit have been known to develop a type of noninfectious mastitis, with a marked decrease in milk production, and milk characterized by cheesy consistency and clots. This has been shown to be accompanied by pathological changes in the mammary gland. Avocado fruit and leaves have been shown to be toxic to various bird species, dogs, goats, and horses.
Up to half of people with a significant latex allergies will develop cross-reactivity to avocados.
We are aware that this is a favorite "healthy" food for many and are making an extra effort to find new studies as they become available. However, there is not much interest in avocados among cancer researchers, so few truly relevant studies are available.
Below are links to recent studies concerning this food. For a more complete list of studies, please click on avocados.