A study published in the American Journal of Clinical Nutrition examined the relation between baseline plasma vitamin C concentrations and risk of incident stroke. The study included a British population of over 20,000 adult men and women. The participants completed a health questionnaire and attended a clinic during 1993–1997.

After an average follow-up time of 9.5 years, the participants in the top fourth of plasma vitamin C levels had a 42% lower risk of stroke compared to those with the lowest levels. These results were independent of age, sex, smoking, BMI, blood pressure, cholesterol, physical activity, diabetes, social class, alcohol consumption, and any supplement use.

Plasma vitamin C concentrations, therefore, may act as an indicator of lifestyle or other factors associated with reduced stroke risk and may be helpful in determining those at high risk of stroke.

American Journal of Clinical Nutrition, Vol. 87, No. 1, 64-69, January 2008.

A combination of prolonged exercise and fish oil can dramatically reduce levels of a fat that can cause hardening of the arteries, a leading cause of heart disease. Fat in the bloodstream is a primary contributor to atherosclerosis, or partial blockage of the arteries.

A study found that people who do prolonged, aerobic exercise have muscle cells that are able to quickly break down and reduce levels of a fat called triglycerides. Taking a fish oil supplement can reduce triglyceride levels even more.

The researchers studied triglyceride levels in recreationally active men after they’d eaten high-fat meals. One group ate a fatty meal after they exercised. A second group ate a high-fat meal after taking a four-gram fish oil supplement. A third group ate a high-fat meal after exercising and taking the fish oil supplement. A control group ate a high-fat meal only.

The study found a 38 percent decline in peak triglyceride levels in the men who took a fish oil supplement before they ate a high-fat meal. Peak triglyceride levels dropped 50 percent in the men who exercised and took a fish oil supplement before they ate a high-fat meal.

Regular exercise and fish oil supplements may be beneficial for people who are concerned about maintaining a healthy triglyceride level.

In a similar study, combining fish-oil supplements with regular exercise improved both body composition and heart disease risk factors. Overweight participants with various heart disease risk factors were assigned to one of three groups: Fish oil (approximately 1.9 grams/day of omega-3 fats), fish oil and exercise, or placebo (sunflower oil). The exercise group walked 3 days/week for 45 minutes. Heart disease risk factors and body composition were measured at 0, 6, and 12 weeks. The group taking fish oil had a significant reduction in triglycerides, increased HDL cholesterol, and improved arterial vasodilation (blood flow). Both fish oil and exercise independently reduced body fat.

This study showed that increasing intake of omega 3 fatty acids could be a useful addition to exercise programs aimed at improving body composition and decreasing cardiovascular disease risk.

Metabolism. 2004 Oct;53(10):1365-71.

Am J Clin Nutr. 2007 May;85(5):1267-74.

In a study published in the Archives of Internal Medicine, over 19,000 men were recruited to determine the relationship between cardiorespiratory fitness (CRF) and mortality risk in healthy men and those with metabolic syndrome. The study group, which included about 3,800 men with metabolic syndrome, were evaluated for fitness and then followed for up to 17 years.

Healthy men who were out of shape at the beginning of the study were three times as likely as their fit peers to die of cardiovascular disease. While men with metabolic syndrome were 89 percent more likely than healthy men to die of heart disease over the years, men with metabolic syndrome who were unfit had twice the death rate as their fit counterparts.

According to the researchers, “This study strengthens the argument for aggressive public health campaigns aimed at increasing physical activity levels in the population.”  Fitness, regardless of body weight, can provide a strong protective effect against premature death in men with metabolic syndrome as well as healthy men.

Arch Intern Med 2004 May 24;164(10):1092-7

A study conducted at Duke University and published in the journal Chest compared the effects of three different exercise regimens on fitness improvements in overweight men and women who were at risk for heart disease.

Broken into four groups, the volunteers either did not exercise, walked briskly for 12 miles a week at a moderate intensity, walked briskly or jogged slowly 12 miles a week at a vigorous intensity, or jogged 20 miles a week at a vigorous intensity.

Two measurements of fitness – time to exhaustion and oxygen consumption – were measured before and after 7 to 9 months of training.

All exercise groups saw fitness improvements compared to baseline. Results indicated that two to three hours of mild exercise a week at a moderate intensity is sufficient to increase aerobic fitness and cut the risk of cardiovascular disease. Increasing either the intensity or the amount of exercise provided additional improvements in fitness.

Although more vigorous exercise should still be encouraged for maximum benefit, this study demonstrates that it is appropriate to recommend mild exercise to improve fitness levels and reduce cardiovascular disease risk, especially in those who are overweight and sedentary.

Chest. 2005;128:2788-2793.