High levels of vitamin D may be linked to lower risk of colorectal cancer, the fourth most common cancer in the United States.

In a new study, researchers found that participants with the highest levels of vitamin D in their blood had up to a 40 percent reduced risk of colorectal cancer (compared to study members with the lowest vitamin D levels). The study included 1,248 people diagnosed with colorectal cancer, as well as 1,248 people who were free of the disease.

In previous research, scientists discovered that vitamin D may help prevent colon cancer by aiding the body in eliminating a highly toxic substance known as lithocholic acid. Since it's difficult to obtain your recommended daily intake of D solely through dietary sources, many medical experts recommend increasing your vitamin D levels by taking a dietary supplement.

Practicing Zen meditation may help thicken certain brain regions and lessen your sensitivity to pain, according to a new study.

For the study, researchers recruited 17 meditators and 18 non-meditators. To measure the participants' pain sensitivity, the researchers applied a heated plate to each individual's calf. In analyzing brain scans of the study members, they found that brain regions involved in regulating pain and emotion were significantly thicker in those who practiced meditation.

In past research, scientists have found that meditation could help improve pain management for people with coping with chronic pain. In particular, meditation has been found to lessen pain and reduce stress in people dealing with conditions like low back pain and fibromyalgia.

A number of other mind-body techniques (including tai chi, guided imagery, and yoga) may also benefit people struggling with chronic pain conditions.

Preliminary research suggests that green tea could help shield your eyes from the harmful effects of glaucoma. In a study on rats, researchers determined that green tea consumption helped defend the animals' eyes from free-radical-induced damage.

A leading cause of blindness in the U.S., glaucoma develops when fluid pressure builds up in the eyes and impairs the optic nerve. Past research shows that oxidative stress (a process that occurs when free radicals overwhelm the body's ability to neutralize them) may contribute to the onset of glaucoma. Known to knock out free radials, antioxidants are abundant in green tea.

In their new study, scientists demonstrated that drinking green tea can help deliver antioxidants to eye tissues and possibly protect against oxidative stress. However, it's too soon to tell whether green tea consumption could have the same effect on human eye health.

In previously published studies, investigators have found that the herb ginkgo biloba may also benefit people with glaucoma.

Bilberry extract may help keep blood sugar in check, according to a recently published study. In tests on mice, scientists discovered that the antioxidant-rich extract helped lower the animals' blood sugar levels and increase their insulin sensitivity.

The study involved mice predisposed to develop diabetes. Among those fed a bilberry-enriched diet for five weeks, researchers observed significantly greater activation of an enzyme known to regulate insulin secretion. Called AMP-activated protein kinase (or AMPK), this enzyme has also been found to promote the breakdown of fat. In the study, AMPK appeared to help control the mice's abnormally high blood sugar levels.

A fruit closely related to blueberries, bilberry is often used in natural treatment of eye conditions (such as glaucoma, macular degeneration, and cataracts). The antioxidants in bilberry are also thought to strengthen the walls of blood vessels, as well as curb inflammation.