In the News

Omega-3 May Not Reduce Recurrence of Atrial Fibrillation

Fructose-rich Beverages Associated With Increased Risk of Gout in Women

Yoga’s Effect on Mood and Anxiety Linked to Increased Levels of Critical Brain Chemical

Combined Aerobic and Resistance Training Helps Patients With Diabetes

Omega-3 May Not Reduce Recurrence of Atrial Fibrillation

Although some data have suggested that omega-3 fatty acid supplements, such as from fish oil, may improve treatment of atrial fibrillation, a randomized trial with more than 600 patients finds that treatment with high-dose prescription omega-3 did not reduce the recurrence of atrial fibrillation over 6 months, according to a study in the December 1 issue of JAMA.

Peter R. Kowey, MD, of the Lankenau Institute for Medical Research, Wynnewood, Pennsylvania, and colleagues conducted a randomized clinical trial to assess the efficacy of a pure prescription formulation of omega-3 fatty acids (prescription omega-3) at a dose considerably higher than has been tested in previous trials for preventing recurrent atrial fibrillation. The study included 663 US outpatient participants with confirmed symptomatic paroxysmal (sudden attacks) (n = 542) or persistent (n = 121) atrial fibrillation (AF) with no substantial structural heart disease who were recruited from November 2006 to July 2009 (final follow-up was January 2010). Participants received prescription omega-3 (8 g/d) or placebo for the first 7 days and prescription omega-3 (4 g/d) or placebo thereafter through week 24.

After 6 months of follow-up, the researchers found that in the paroxysmal group, there were 129 documented symptomatic AF or flutter (abnormal, rapid heart beat) events (48%) in the placebo group and 135 (52%) in the prescription group. In the persistent AF group, there were 18 documented symptomatic AF or flutter events (33%) in the placebo group and 32 (50%) in the prescription group, and in the two groups combined, there were 147 events (46%) in the placebo group and 167 (52%) in the prescription group.

None of the secondary efficacy endpoints, including first recurrence of AF or flutter in the persistent group and both groups combined, reached statistical significance. Sixteen participants (5%) taking placebo and 12 (4%) taking prescription omega-3 discontinued study medication due to an adverse event.

“In this population of patients with symptomatic paroxysmal AF or persistent AF, and no evidence of substantial structural heart disease, prescription omega-3 did not show evidence of reducing the recurrence of symptomatic atrial fibrillation,” the authors write.

They add that several factors might contribute to the discordance between their findings and those of other studies: “Either the positive results reported in some trials represent a chance effect of small sample sizes or the differences are real. If the latter, there are several possibilities, including differences in the study populations, in population-specific AF mechanisms, in dosing regimens and product formulations, or in concomitant therapies. In our study, nearly half the events occurred during the first 2 weeks of follow-up, suggesting that fish oil may not have rapid effects, even with high-loading doses.”

Fructose-rich Beverages Associated With Increased Risk of Gout in Women

Consumption of fructose-rich beverages, such as sugar-sweetened sodas and orange juice, is associated with an increased risk of gout among women, although their contribution to the risk of gout in the population is likely modest because of the low incidence rate among women, according to a study in a recent issue of JAMA.

Gout is a common and very painful inflammatory arthritis. According to the authors, the increasing incidence of gout in the United States over the last few decades (ie, an incidence of 16/100 000 people in 1977 vs 42/100 000 people in 1996) coincided with a significant increase in soft drink and fructose consumption. “Fructose-rich beverages such as sugar-sweetened soda and orange juice can increase serum uric acid levels and, thus, the risk of gout, but prospective data on the relationship are limited,” the authors write.

Hyon K. Choi, MD, DrPH, of the Boston University School of Medicine and colleagues examined the relationship between intake of fructose-rich beverages and fructose and incidence of gout in a large group of women. The study consisted of data from the Nurses’ Health Study, a US prospective cohort study spanning 22 years (1984-2006). The researchers analyzed data from 78 906 women with no history of gout at the beginning of the study and who provided information on intake of beverages and fructose through validated food-frequency questionnaires.

During 22 years of follow-up, the researchers documented 778 newly diagnosed cases meeting American College of Rheumatology survey criteria for gout. They found that increasing intake of sugar-sweetened soda was associated with increasing risk of gout. Compared with consumption of less than 1 serving per month, women who consumed one serving per day had a 74% increased risk of gout, and those with two or more servings per day had a 2.4 times higher risk. Diet soft drinks were not associated with the risk of gout.

Orange juice intake was also associated with risk of gout. Compared with women who consumed less than a glass (6 oz) of orange juice per month, women who consumed 1 serving per day had a 41% higher risk of gout, and there was a 2.4 times higher risk with two or more servings per day. Also, compared with women in the lowest quintile (fifth) of free fructose intake, women in the highest quintile had a 62% higher risk of gout.

The authors note that although the relative risks of gout associated with fructose-rich beverages among women were substantial, the corresponding absolute risk differences were modest given the low incidence rate of gout among women.

The researchers add that their findings have practical implications for the prevention of gout in women and that physicians should be aware of the potential effect of these beverages on the risk of gout.

Yoga’s Effect on Mood and Anxiety Linked to Increased Levels of Critical Brain Chemical

Yoga has a greater positive effect on a person’s mood and anxiety level than walking and other forms of exercise, which may be due to higher levels of the brain chemical gamma-aminobutyric acid (GABA) induced in practitioners of the exercise, according to an article in The Journal of Alternative and Complementary Medicine.

Yoga has been shown to increase the level of GABA, a chemical in the brain that helps to regulate nerve activity. GABA activity is reduced in people with mood and anxiety disorders, and drugs that increase GABA activity are commonly prescribed to improve mood and decrease anxiety.

Tying all of these observations together, the study by Chris Streeter, MD, from Boston University School of Medicine and colleagues demonstrates that increased GABA levels measured after a session of yoga postures are associated with improved mood and decreased anxiety. Their findings establish a new link between yoga, higher levels of GABA in the thalamus, and improvements in mood and anxiety based on psychological assessments. The authors suggest that the practice of yoga stimulates specific brain areas, thereby giving rise to changes in endogenous antidepressant neurotransmitters such as GABA.

Combined Aerobic and Resistance Training Helps Patients With Diabetes

Performing a combination of aerobic exercise and resistance training was associated with improved glycemic levels among patients with type 2 diabetes compared to patients who did not exercise, according to a study in a recent issue of JAMA. The level of improvement was not seen among patients who performed either aerobic exercise or resistance training alone.

Although it is generally accepted that regular exercise provides substantial health benefits for individuals with type 2 diabetes, the exact exercise type (aerobic vs resistance vs both) has been unclear.

Timothy S. Church, MD, MPH, PhD, of Louisiana State University, Baton Rouge, and colleagues conducted the HART-D trial, which compared among 262 sedentary women and men with type 2 diabetes the effect of aerobic training, resistance training, and a combination of both on change in hemoglobin A1c levels (HbA1c; a minor component of hemoglobin and to which glucose is bound; HbA1c levels are used to monitor the control of diabetes mellitus). Study participants were 63.0% women, 47.3% nonwhite, aged 56 years on average, and had an HbA1c level of 7.7% and a duration of diabetes of 7.1 years. The individuals were enrolled in the 9-month exercise program between April 2007 and August 2009. Forty-one participants were assigned to the nonexercise control group, 73 to resistance training sessions, 72 to aerobic exercise sessions, and 76 to combined aerobic and resistance training.

The researchers found that the absolute change in HbA1c in the combination training group vs the control group was -0.34%. In neither the resistance training (-0.16%) nor the aerobic (-0.24%) groups were changes in HbA1c significant compared with those in the control group. The prevalence of increases in hypoglycemic medications were 39% in the control, 32% in the resistance training, 22% in the aerobic, and 18% in the combination training groups.

Compared with the control group, only the combination-training group improved maximum oxygen consumption. In all exercise groups, waist circumference decreased from -.75 to -1.1 inches compared with the control group. The resistance-training group lost an average of 3.1 lbs fat mass, and the combination-training group lost an average of 3.7 lbs compared with the control group.

The primary finding from this trial is that although both resistance and aerobic exercise provide benefits, only the combination resulted in reductions in HbA1c levels. It is also significant that the difference in HbA1c between the combination training group and the control group at follow-up occurred even though the control group had increased its use of diabetes medications and the combination-training group decreased its diabetes medication use.