THE QUESTION: Wear and tear on the joints is most often blamed for osteoarthritis. Might the nutrients in foods have a protective effect?

THE QUESTION: Wear and tear on the joints is most often blamed for osteoarthritis. Might the nutrients in foods have a protective effect?

THIS STUDY: It involved 293 generally healthy adults (average age, 58) who had no knee pain. The nutrient content of each participant's diet was determined at the start of the study. Ten years later, their knee cartilage and bone were examined by magnetic resonance imaging (MRI). People who reported consuming the highest amounts of vitamin C, primarily from eating fruit, were the least likely to have developed bone changes associated with osteoarthritis. Little or no link was found between bone changes and vitamin E or most carotenoids.

WHO MAY BE AFFECTED? Adults. Osteoarthritis affects an estimated 21 million Americans. The risk increases as people age.

CAVEATS: Data on supplement use, which might have affected the findings, were not included in the analysis. Information on diet was based on the participants' recall. The study did not indicate how many people received an osteoarthritis diagnosis during the 10-year period.

FIND THIS STUDY: It's in the July online issue of Arthritis Research & Therapy.

LEARN MORE ABOUT osteoarthritis at www.niams.nih.gov/hi and www.arthritis.org.

THE QUESTION: Soft-drink consumption has been tied to weight gain and higher blood pressure.

Might such drinks also boost blood cholesterol, sugar and fat levels, raising the risk for metabolic syndrome, which can lead to heart disease and diabetes?

THIS STUDY: It analyzed data on 6,039 people, most in their 50s. Over four years, metabolic syndrome was diagnosed in 1,239 of them. Those who reported drinking one or more soft drinks a day — whether regular or diet, caffeinated or decaffeinated — were 44 percent more likely to have developed the syndrome than those who drank less. They were also at greater risk for obesity, increased waist size, high triglycerides or blood glucose and low levels of high-density lipoprotein ("good" cholesterol).

WHO MAY BE AFFECTED? People who consume soft drinks.

CAVEATS: Differences in lifestyle and eating habits may have affected the results. The surprise finding that sugar-free sodas were also linked to metabolic syndrome suggests that something other than sugar content may be involved. One theory is that a high sweetness level makes people crave more sweets. Data on soft drink consumption were based on the participants' recall.

FIND THIS STUDY: It's in the July 24 issue of Circulation.

LEARN MORE ABOUT metabolic syndrome at www.nhlbi.nih.gov/health and www.mayoclinic.com.

The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.