Nutrition News Bites: Vitamin D for Lung Health, Omega-3s for Healthier Hearts

Vitamin D for Stronger Lungs

Research continues to uncover new benefits of vitamin D, which has been linked to everything from bone strength to reductions in the risk of prostate and colon cancers. A study now reports that higher blood levels of this vitamin support better lung function (1).

Using data collected from over 14,000 adults who took part in a US National Health and Nutrition Examination Survey, investigators divided the participants into 5 groups based on their blood levels of vitamin D. They then compared how well the groups had done on tests of lung function. FEV (forced expiratory volume) measures how much air you can exhale in a second, while forced vital capacity (FVC) determines the amount of air you can rapidly blow out after taking a deep breath.

People with the highest vitamin D levels had considerably stronger FEV scores and better FEC rates, even after adjusting for factors such as smoking and exercise. The study also found more vitamin D naturally occurring in men than in women, and that the older and more obese a person was, the less vitamin D was present. The researchers think that vitamin D may be helping the remodeling of tissues in the lung.

While the study showed a "definite relationship between vitamin D and lung function", the study's lead author cautioned that it isn't clear whether increases in vitamin D can favorably affect lung function in people who already have chronic respiratory diseases.

The body's capacity to produce vitamin D from sunlight exposure declines with age, and many experts believe that older adults need even higher levels of this vitamin than the currently recommended daily dose of 400 IU for those over 50 and 600 IU for those 70 years and older.

Omega-3s and Healthier Heart Rates

Many epidemiologic and clinical trials have documented the heart-protective effects of the omega-3 fatty acids found in cold-water fish.

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In recent years, studies have found that consuming more omega-3s reduces the risk for sudden death in people with coronary heart disease. Sudden death occurs when the heart stops abruptly, a condition also known as cardiac arrest. Most cardiac arrest occurs when electrical impulses in the heart become rapid and/or chaotic. The omega-3 fats are believed to fight against sudden death by regulating the heartbeat and preventing irregular rhythms.

A new study designed to explore the possible mechanisms in which fish oil protects against the risk of sudden death has shown that supplementation with omega-3 fatty acids significantly decreases heart rate while at rest, and accelerates its return to normal after exercise (2).

In this well-controlled but small study, men with a history of heart attack took omega-3 fatty-acid supplements (about 800 mg daily) or placebo for 4 months, then switched to the alternate treatment for another 4 months. Resting heart rate significantly decreased with the omega-3 supplement, and heart rate returned to normal much faster after the men completed a stress test. The decrease in heart rate at 1 minute post-exercise was 19% greater with omega-3s.

"This decrease in heart rate could help explain the decreased risk in sudden death with omega-3 fatty acids", noted the lead author, "because there is a relationship between resting heart rate and the risk of sudden death: The higher the rate, the higher the risk."

While this study focused on people who had already experienced a heart attack, the omega-3s may help others too. In 2003, researchers reported that healthy men who regularly ate fish had lower average heart rates - a sign of a much healthier heart.

Photo courtesy of www.cfsan.fda.gov

1. Black PN et al. Relationship between serum 25-hydroxyvitamin d and pulmonary function in the third national health and nutrition examination survey. Chest. 128:3792-8, 2005.
   
2. O'Keefe JH et al. Effects of omega-3 fatty aids on resting heart rate, heart rate recovery after exercise, and heart rate variability in men with healed myocardial infarctions and depressed ejection fractions. Am J Cardiology 97:1127-30, 2006.