The Color Orange

Colors make the world delightful. It’s hard to imagine a life without blue skies, green plants, and the sometimes fiery, sometimes muted, highlights we see in the world.

Colors also affect our psyche; they create an emotional response. Too many gray days breed discontent, prisons are being painted in pastels of various colors to control moods, and businesses use different colors to make people hungry, content, excited, or calm.

Color also can affect our health, especially if you consider that, in the plant world, coloring is achieved through carotenoids, which not only supply us with something pleasant to look at, but also healthful properties.

Orange

Orange is the color of carrots, yams, cantaloupes, butternut squash, and pumpkin. In the natural and healthful world, you would say that orange represents beta carotene. Beta carotene gets its name from carrots, but green leafy vegetables like spinach also contain beta carotene. The orange is masked by the green of chlorophyll. What does the color orange do for us healthwise?

The cancer connection

The beta carotene-cancer link was made during research on vitamin A (which the body manufactures from beta carotene) and cancer in 1981. This year saw reports published in Nature, the International Journal of Cancer, and the Lancet. In late 1981, the New York Times featured an article about the risk of lung cancer and how beta carotene reduced this risk.

Official recognition came in 1982, when the National Academy of Sciences’ report, Diet and Cancer, gave the academic and medical "seal of approval" to the link between beta carotene and vitamin A and reduced risk of cancer. Since then, there has been reconfirmation of this link.

In a study reported in the July 1996 issue of Carcinogenesis, the effect of beta carotene and selenium on pancreatic carcinogenesis in rats was investigated. The researchers noted that both beta carotene and selenium might have had chemopreventive effects, especially when added to diets during the late promotion phase of the carcinogenic process.

A 1998 study in Pancreas on pancreatic carcinogenesis showed similar results. In this study, the effects of alpha carotene, beta carotene, palm carotene, and green tea polyphenols (GTP) on the progression stage of pancreatic carcinogenesis were studied in Syrian hamsters. Inhibitory effects were noted for beta carotene and palm carotene (which includes beta carotene). GTP also showed inhibitory effects.

In 1997, Harvard Medical School released research that indicates that beta carotene can sharply reduce the risk of prostate cancer in men with low beta carotene blood levels. (Cancer Weekly Plus, June 9, 1997). In this research, the diets, lifestyles, and health of more than 22,000 male doctors were observed. Half of the doctors were given 50 mg (80,000 IU) of beta carotene every other day.

The findings indicate that physicians with low levels of beta carotene were one-third more likely to develop prostate cancer. The doctors who supplemented with beta carotene were 36 percent less likely to develop prostate cancer than those who ate few beta carotene-rich fruits and vegetables and did not take beta carotene supplements.

An article in the American Journal of Clinical Nutrition (August 1997) notes that epidemiological studies reveal that people with high intakes of beta carotene or high blood concentrations of this nutrient have a reduced risk of various diseases, including cancer and heart disease. The authors note that this is a credible hypothesis, because

increased consumption of beta carotene is strongly associated with reduced risk of cancer;
beta carotene is a dietary antioxidant and antioxidants inhibit early stages of carcinogenesis; and
beta carotene reduces cancer in experimental animal models.

Why the link?

The link between beta carotene and cancer prevention may be found in beta carotene’s effect on the immune system.

Michelle Santos, et al., writing in the November 1996 issue of The American Journal of Clinical Nutrition, notes that beta carotene may increase the activity of natural killer (NK) cells. NK cell activity has been postulated to be an immunologic link between beta carotene and cancer prevention. The article states that, "Our results show that long-term beta carotene supplementation enhances NK cell activity in elderly men, which may be beneficial for viral and tumoral surveillance." This has been reconfirmed in a more recent study by Santos (The American Journal of Clinical Nutrition; July 1998).

Another reason for beta carotene’s effect on cancer may be due to its influence on the gap-junctional communication between cells.

Gap-junctional communication is a way that cells communicate; it is the exchange of small molecules and ions between neighboring cells. All cells within a tissue, with the exception of circulating blood cells and smooth muscle cells, are connected to one another by gap junctions. These communication channels allow the transmission of important cellular messages and play an important part in maintaining a normal cellular environment.

Some scientists believe that beta carotene, and other carotenoids, achieve cancer protection by improving the communication which takes place in these gap junctions. This improved communication may help cells being transformed into cancer cells revert back to being normal.

Most specifically, beta carotene apparently stimulates a molecule that helps the immune system target and destroy cancer cells. It increases the number of receptors on white blood cells for a molecule known as major histocompatibility complex II (MHC II).

MHC II is integral in helping monocytes, a type of white blood cell, direct killer T cells to cancerous cells (Cancer Weekly Plus, Jan. 6, 1997). In other words, beta carotene is integral in directing the immune system to kill cancer cells.