One of the chemicals that the body produces from vitamin A can turn precancerous cells back into healthy cells, even on a genetic level, according to a study conducted by researchers from Thomas Jefferson University and published in March 2014 in the International Journal of Oncology.
The research was supported by grants from Friends for an Earlier Breast Cancer Test and the Pennsylvania Breast Cancer Coalition.
Although researchers have believed for some time that vitamin A may play a role in cancer prevention or treatment, studies have been inconclusive and have often offered mixed results. The new study suggests an answer to this longstanding puzzle: Vitamin A may only act on cancer cells at a very specific point in their development, and even then only at very specific doses.
Four types of cells
The researchers exposed human breast cells at several stages of cancer development to different concentrations of retinoic acid, one of the chemicals produced in the body from the metabolism of vitamin A. The cells were classified as normal, precancerous, cancerous or fully aggressive.
Although retinoic acid appeared to have no effect on normal, cancerous or fully aggressive cells, the effect on precancerous cells was striking: The cells returned to the shape characteristic of normal cells and changed their genetic expression back to normal as well.
“We were able to see this effect of retinoic acid because we were looking at four distinct stages of breast cancer,” researcher Dr. Sandra V. Fernandez said. “It will be interesting to see if these results can be applied to patients.”
The researchers found that there are 443 separate genes that change their expression as a breast cell moves from normal to cancerous. Exposure to retinoic acid returned expression of every one of these genes to normal levels.
“It looks like retinoic acid exerts effects on cancer cells in part via the modulation of the epigenome,” Fernandez said.
In addition to finding that retinoic acid had no effect on cancerous or fully aggressive cells, the researchers discovered that only one of the concentrations tested produced the full effect on the precancerous cells. Concentrations lower than about 1 micromolar had no effect, and higher concentrations were less effective.
The researchers now plan to test retinoic acid on animals with precancerous cells. If those studies are successful, they could then move to testing the substance on humans.
Eat Your Vegetables
The findings are only one of many reasons to eat plenty of orange- and yellow-colored fruits and vegetables, which are high in the beta-carotene that the body turns into vitamin A. Other foods high in vitamin A include meat and dairy products.
Vitamin A is essential for the formation and maintenance of healthy bones and soft tissues including skin and mucous membranes. It also plays a key role in immune health and vision; deficiency typically manifests first as vision problems and greater susceptibility to infection.
Eating beta-carotene-rich fruits and vegetables has another health benefit: Those foods are also rich in the related chemical alpha-carotene (which is also found in bright-green vegetables). In a 2011 study conducted by researchers from the Centers for Disease Control and Prevention and published in the Archives of Internal Medicine, people with the highest blood levels of alpha-carotene were 39 percent less likely to die over the course of an 18-year study than those with the lowest levels.
The greatest effect was seen through lowered death rates from heart disease and cancer. Notably, alpha-carotene-rich foods appeared to protect against lung cancer better than any other vegetables did.
Sources for this article include: