Hawthorn extract, according to a new animal study. In tests on rat pups, scientists discovered that eye drops containing hawthorn extract helped fight cataracts by revving up antioxidant activity.

The world's leading cause of blindness, cataracts develop when fibers in the lens of the eye clump together and result in blurred vision (or complete blindness, if left untreated). In previously published population studies, researchers have found that loading up on lutein and zeaxanthin (antioxidants found in yellow or dark-green leafy vegetables) and omega-3 fatty acids (healthy fats found in flaxseed and certain fish) may help reduce risk of cataracts.

Often touted as a natural remedy for heart health, hawthorn extract has been shown to keep blood pressure in check and prevent atherosclerosis (the buildup of fatty deposits in your arteries) in past research.

To build strong bones, girls may need to start taking vitamin D supplements prior to early adolescence. In a recent study of 73 girls (ages 12 to 14), those who received four doses of 150,000 IU of vitamin D over the period of a year showed no significant improvement in bone health. According to the study's authors, this finding suggests that earlier supplementation is needed in order to make the most of peak bone-building years.

Vitamin D is essential for maintaining normal blood levels of calcium and phosphorous, which in turn helps support the hardening of bones. Running low on vitamin D may lead to the development of osteoporosis, a condition marked by decreased bone density.

Although vitamin D is available in some foods (such as certain fish and fortified cereals), it's difficult to get your recommended daily intake solely through dietary sources. Your body can synthesize vitamin D during exposure to the sun's UVB rays, but getting too much sun can raise your risk of skin cancer. Therefore, many medical experts recommend taking a daily supplement in order to boost your levels of vitamin D.

Filling your plate with foods high in vitamin E may help reduce your risk for Alzheimer's disease, a new study shows.

For the study, researchers sized up dietary information provided by 5,395 participants (all of whom were 55 years or older and did not have dementia between 1990 and 1993). Over the course of about 9.6 years, 465 study members developed dementia. Among the participants with dementia, 365 were diagnosed with Alzheimer's disease. In analyzing their data, the researchers found that study members whose diets were highest in vitamin E were 25 percent less likely to develop dementia. Dietary intake of vitamin C and beta-carotene, however, was not associated with a reduction in dementia risk.

In the study, the major food sources of vitamin E were margarine, sunflower oil, butter, cooking fat, soybean oil, and mayonnaise. The study's authors suggest that vitamin E (considered an antioxidant) may help protect against dementia and Alzheimer's by fighting off free radicals.

Using zinc nasal sprays to soothe cold symptoms may dull your sense of smell, a new study shows.

The study included 25 patients, all of whom had been treated at a nasal dysfunction clinic. The patients reported experiencing a burning sensation immediately after using zinc nasal sprays, followed by a loss of sense of smell within minutes to hours of using the sprays. According to the study's authors, the only "probable explanation for the smell loss is chemical injury due to the use of intranasal zinc." What's more, the study's authors note, previous research suggests that zinc nasal sprays may not be effective when it comes to preventing or treating colds.

In past studies, several other natural remedies have been found to help reduce the duration and/or severity of the common cold. These remedies include herbs like echinacea and astragalus, as well as nutrients like vitamin C.