Diets high in cholesterol can ramp up the speed of cancer tumour growth by up to 100 times, a new study has revealed – but as scary as that is, the findings could also lead to better treatments to stop this from happening.
The research began as a way of studying a correlation between high-cholesterol diets and an increased risk of colon cancer. That link has already been identified but scientists still don't understand much about its cause.
According to the team of researchers, stem cells could be the key: these cells can be turned into almost any kind of cell in the body, and it appears the extra cholesterol is increasing the rate at which these stem cells multiply, and then the rate at which tumours grow.
"We were excited to find that cholesterol influences the growth of stem cells in the intestines, which in turn accelerates the rate of tumour formation by more than 100-fold," says one of the team, Peter Tontonoz from the University of California Los Angeles (UCLA).
"While the connection between dietary cholesterol and colon cancer is well established, no one has previously explained the mechanism behind it."
In tests on mice, the researchers noticed increased tumour growth rates after putting more cholesterol in the animals' diets. Growth rates also increased in another group of mice where a specific gene was changed to get the animals to produce more cholesterol on their own.
The altered gene, which forms an enzyme called Lpcat3, regulates phospholipids; the primary type of fat inside cell membranes. As this supply line was cut off, more cholesterol was produced.
Once the cholesterol levels of the mice rose, the stem cells' ability to multiply increased, which then caused their intestines and gut tissue lining to expand. As a result, the rate of tumour formation in their colons also went up.
Now the challenge is to see if the same cholesterol effect can be noticed for other types of cancers, as well as finding methods for stopping it. If the same results can be recorded in humans, we could have a new way of fighting colon and other cancers.
The research also helps in the ongoing debate over whether statins – drugs which can lower the the level of "bad" cholesterol or low-density lipoprotein (LDL) in the blood – can also reduce the risk of cancer.
Cholesterol is found in the outer membrane of all human cells and is produced by the liver as an essential building block for other substances in the body.
However too much of the fatty stuff in the bloodstream (particularly the LDL type) has been linked to a host of different health issues, including heart attacks and strokes.
Foods rich in saturated fats, trans fats, and certain carbohydrates can increase the levels of unwanted cholesterol in the body. As a result most experts warn against eating too much red meat and dairy food.
Let's hope this discovery of how cancer tumours can be sent into overdrive eventually leads to better ways of reversing their growth.
The research has been published in Cell Stem Cell.