Saturday NOv 30, 2013 (foodconsumer.org) -- A new study in Cell Reports has found evidence to support the observation that high serum cholesterol can be a risk factor for breast cancer.  High cholesterol has been already known to be a risk factor for cardiovascular disease and Alzheimer’s disease.

The study led by Q. Wu and colleagues from University of Texas Southwestern Medical Center in Dallas, TX shows that a metabolite of cholesterol called 27-Hydroxycholesterol or 27-HC for short promotes cell-autonomous ER positive breast cancer growth in mice.

Prior to this research, "estrogen is the only known endogenous estrogen receptor (ER) ligand tat promotes ER+ breast cancer growth," the authors state in their report.  Now the researchers found that patients with ER+ breast cancer have high levels of 27-HC in normal breast and even higher levels of this cholesterol metabolite in the breast with tumors.

The 27-HC levels were increased because the expression of the 27-HC metabolizing enzyme CYP7B1 in tumors were diminished for some reason, according to the study.  And the reduced levels of the enzyme were associated with poorer patient survival.

Also in MCF-7 cells, 27HC was produced and poised to stimulate cell-autonomous ER dependent and GDNF-RET dependent cell proliferation.

All evidence combined indicates that "27HC is a locally modulated, nonaromatized ER ligand that promotes ER+ breast tumor growth."

Another study published also recently in the Nov 2013 issue of Science explained hypercholesterolesmia is linked to pathophysiology of breast cancer via 27-hydroxycholesterol.

Authors of the study E. R. Nelson from Duke University School of Medicine in Durham, NC and colleagues said that hypercholesterolemia or simply high cholesterol is a risk factor for estrogen receptor positive (ER+) breast cancer and is correlated with a decreased response of tumors to endocrine therapy.

The study shows that 27-hydroxycholesterol (27HC) increases ER-dependent growth and LXR-dependent metastasis in mice with breast cancer.   

The study also reveals that cholesterol imposes a promotional effect on tumor pathology through the action of the cytochrome P450 oxidase CYP27A1 which converts cholesterol to 27HC.

The authors also found that in human breast cancer tissue, high CYP27A1 expression levels were correlated with high tumor grades.

The findings suggest that both lowering circulating cholesterol levels and blocking the conversion of cholesterol to 27HC may help prevent and or treat breast cancer.

It has already been found in other studies that cholesterol lowering drugs statins are associated with reduced risk of breast cancer and other types of malignancies.  Should we take statins to prevent breast cancer?  Maybe. Just be aware that long-term use of statins can cause side effects such as muscle pain.  More consumer-friendly alternatives are available including red yeast rice, which has been found as effective as statins in lowering cholesterol.

The role of 27HC in the development of ER+ breast cancer was reported as early as in 2008 again by researchers at Duke University Medical center in Durham, North Carolina.

In the Jan 2008 issue of Molecular Endocrinology, C. D. DuSell and colleagues reported that "27-hydroxycholesterol is an endogenous selective estrogen receptor modulator."

The finding basically explains the observation that obese and high cholesterol individuals are at elevated risk of breast cancer.

The researchers published a similar study in Oct 2008 in Trends Pharmacological Sciences.

In another study published in May 2012 in Experimental and Therapeutic Medicine, P. Cruz and colleagues from Laboratorio de Nutrición y Regulación Metabólica, INTA-Universidad de Chile in Santiago compared the proliferative effects on mammary cancer cells of 27HC and estradiol, an estrogen, which also promotes the growth of ER+ breast cancer.

They found simvastatin blocked 27OHC proliferation-stimulatory activity and an α-fetoprotein-derived cyclic nonapeptide inhibited estradiol-stimulated proliferation.  The study demonstrated that cholesterol metabolite 27HC is major risk factor for ER+ breast cancer and explains why obese breast cancer patients suffer increased breast cancer growth.

Dietary supplements that can help lower cholesterol include green blue algae spirulina, red yeast rice, black radish juice, plant sterol and stanols, soya protein, beta-glucans, vitamin C, berberine, policosanols, artichoke  leaf, and nola cactus among others.

Other things that can help lower cholesterol include avoiding animal foods with high cholesterol such as eggs, seafood, meat and milk, eating a vegetarian diet, physical exercise and good night sleep.

Bewere that some well-known "natural health advocate" promotes eating cholesterol by claiming that cholesterol is good for the brain.  Food consumers should do their own home work to understand whether cholesterol is good for their health.  High cholesterol is a known risk factor for heart disease, cancer and also Alzheimer's disease and dietary cholesterol is known to increase circulating cholesterol. (David Liu, PHD)