JOURNAL: Gut 2004;53:246-250.
AUTHORS: Dr. Tim Card
ABSTRACT: Antibiotic use is associated with the subsequent development of Crohn's disease.
COMMENTARY: Genetic factors are recognized as playing a role in Crohn's disease, but other elements must be involved to account for the rise in incidence over the last century.
Since intestinal flora is associated with Crohn's disease, Dr. Card's group surmised that antibiotics, by interfering with normal colonization, may be one of the missing components in disease etiology. They therefore analyzed data from the General Practice Research Database, where antibiotic use had been prospectively recorded.
They identified 587 patients with Crohn's disease for whom data had been recorded for at least 5 years prior to diagnosis, with whom the authors matched 1460 control subjects by age and gender.
Antibiotics were prescribed at least once 2 to 5 years before the index date for 71% of cases and 58% of controls (p < 0.001). In multivariate analysis excluding subjects with symptoms suggestive of Crohn's disease and those prescribed a gastrointestinal drug 2 to 5 years before the index date, the odds ratio was 1.53. This, according to Dr. Card's team, "is evidence against the association being a result of reverse causation.
The authors estimate that the population attributable fraction was 17% for antibiotics, versus 10% for smoking, another recognized risk factor for Crohn's disease.
STUDY: Dietary intake of folate and risk of stroke in US men and women.
JOURNAL: Stroke 2002;33:1183–9.
AUTHORS: Bazzano LA, He J, Ogden LG, et al
ABSTRACT: The evidence supporting the many health benefits of folic acid has been enhanced with the recent publication of a study in the journal Stroke. The study found that people with a dietary intake of at least 300 mcg per day of folic acid reduced their risk of stroke and heart disease by 20% and 13%, respectively, compared with those who consumed less than 136 mcg of folic acid per day.
COMMENTARY: After years of research confirming that pregnant women taking folic acid are less likely to have children with neural tube defects, this study is one of the first to demonstrate that dietary intake of folic acid not only reduces heart disease risk, but also prevents stroke. Stroke and heart disease are two of the top three causes of death in the United States.
The new study followed the eating habits of 9,764 men and women between the ages 25 and 74 who showed no signs of heart disease at the beginning of the study. Other trials suggest that 400 mcg per day of folic acid may prevent heart disease by lowering homocysteine levels in the blood. Homocysteine has been shown to be a significant risk factor for heart disease; the risk of having a heart attack goes up as homocysteine levels rise.
The protective effects against heart disease and stroke reinforce the benefits of supplementing with folic acid, which healthcare professionals have long known.
Good sources of folic acid include dark, green leafy vegetables such as kale, Swiss chard and mustard greens, oranges, Brewer’s yeast, soybeans, beets, asparagus, and red meat. Dietary intake can be augmented with folic acid supplements.
1. Bazzano LA, He J, Ogden LG, et al. Dietary intake of folate and risk of stroke in US men and women. Stroke 2002;33:1183–9.
2. Rydlewicz A, Simpson JA, Taylor RJ, et al. The effect of folic acid supplementation on plasma homocysteine in an elderly population. Q J Med 2002;95:27–35.
3. Tice JA, Ross E, Coxson PG, et al. Cost-effectiveness of vitamin therapy to lower plasma homocysteine levels for the prevention of coronary heart disease. JAMA 2001;286:936–43.
4. Quinlivan EP, McPartlin J, McNulty H, et al. Importance of both folic acid and vitamin B12 in reduction of risk of vascular disease. Lancet 2002;359:227–8.
5. Werler MM, Shapiro S, Mitchell AA. Periconceptional folic acid exposure and risk of occurrent neural tube defects. JAMA 1993;269:1257–61.
6. Berry RJ, Li Z, Erickson JD et al. Preventing neural tube defects with folic acid in China. N Engl J Med 1999;341:1485–90.
7. Reynolds EH. Effects of folic acid on the mental state and fit frequency of drug treated epileptic patients. Lancet 1967;1:1086–8.
8. Seligmann H, Potasman I, Weller B, et al. Phenytoin-folic acid interaction: a lesson to be learned. Clin Neuropharmacol 1999;22:268–72.
STUDY: Physical activity is associated with a lower risk of prevalent and incident depression
JOURNAL: Am J Epidemiol 2002;156:328-334.
AUTHORS: Dr. William J. Strawbridge
ABSTRACT: Physical activity is associated with a lower risk of prevalent and incident depression among older adults.according to a report in the American Journal of Epidemiology.
COMMENTARY: Dr. William J. Strawbridge, of the Public Health Institute, Berkeley, California, and colleagues studied 1947 subjects from the Alameda County Study who were between 50 and 94 years of age at baseline and were followed for 5 years.
The investigators examined the effects of physical activity (measured on an 8-point scale) on depression, with and without excluding disabled patients.
Every 1-point increase in physical activity protected against both prevalent depression (adjusted odds ratio [OR] = 0.90) and incident depression (adjusted OR = 0.83) over 5 years after adjusting for age, sex, ethnicity, financial strain, chronic conditions, disability, body mass index, alcohol consumption, smoking, and social relations. The incidence results were not attenuated by exclusion of disabled patients (adjusted OR = 0.79), the researchers found.
Regular physical activity, such as walking, exercising, swimming, or playing active sports for older adults will reduce the risk of subsequent depression. This benefit is similar for those with and without physical disabilities.
The most common form of physical activity for members of the Alameda County Study is taking long walks, which shows that physical activity does not have to involve elaborate equipment.
The investigators note that it is plausible that persons with high levels of physical activity are also more likely to engage in other beneficial health behaviors such as not smoking, avoiding obesity, and not drinking to excess.
Keep in mind that a little exercise goes a long way.
Get out there and do something.
STUDY: Initial findings in people support calorie effect seen in lab animals.
AUTHORS: George S. Roth
ABSTRACT: For the first time, researchers have found evidence suggesting people may live longer by eating fewer calories each day, a dietary restriction that already has shown in experiments to extend the lives of laboratory animals by up to 40 percent.
COMMENTARY: Even if the evidence proves to be correct, it’s unknown how much extra time people might live.
Laboratory studies for decades have shown that reducing the calories fed to lab mice and rats enabled the animals to live much longer.
Now, George S. Roth and his colleagues at the National Institute on Aging say they have preliminary evidence that biological changes that help create superaged rodents may also work in humans.
The biological markers — lower temperature, lower insulin levels and a steady level of a steroid hormone called DHEAS — all occur in restricted-diet rodents that live about 40 percent longer than fellow rodents on a normal diet.The same biological markers have now been found in men who are living longest in a continuing study in Baltimore on aging.
Men whose biomarkers were similar to those of the calorie-restricted, long-lived rodents were dying at a much slower rate than were men with other biomarker measurements.
JOURNAL: Lancet. 2004;363:411-412, 417-421, 422-428
AUTHORS: Robert G. Will
ABSTRACT: — Blood transfusion may be a mode of transmitting variant Creutzfeldt-Jakob disease (vCJD).
COMMENTARY: On Dec. 17, 2003, the U.K. announced the death from vCJD of an individual who had previously received a red cell transfusion from a donor who subsequently developed vCJD. Symptoms of vCJD developed in the recipient 6.5 years after the transfusion, and in the donor 3.5 years after the transfusion.
Using the national blood-donor database and the U.K. CJD register, a team from the National CJD Surveillance Unit of Western General Hospital in Edinburgh, U.K., identified 48 individuals, including the subject of the case report, who received a blood component from 15 donors who later developed vCJD.
"Our findings raise the possibility that this infection was transfusion transmitted," senior author Robert G. Will says in a news release. "Infection in the recipient could have been due to past dietary exposure to the BSE [bovine spongiform encephalopathy] agent.
The clinical presentation and preliminary examination of neuropathology of this patient were typical of vCJD. Although magnetic resonance imaging did not show the classical pulvinar sign seen in most cases of vCJD, fluid attenuated inversion recovery sequences with the highest sensitivity were not obtained.
The red blood cells transfused in this patient were not leucodepleted, but the authors note that the efficiency of leucodepletion in reducing infectivity is uncertain.
The surviving recipients of blood transfusions from donors who later developed vCJD are being informed of their possible increased risk of developing vCJD and warned not to donate organs or blood.
"To date, no case of vCJD has been identified with a history of exposure to fractionated blood products," the authors write. "The most direct action to reduce risk is a careful case-by-case evaluation of the need for blood transfusion."
The National Blood Service supported this study.
In an animal study in the same issue of The Lancet, Corinne Lasmézas and colleagues, from the French Atomic Energy Commission, compared the degree of tissue infectivity among macaques with oral or intravenous exposure to tissue containing the BSE agent.
Using the misfolded prion protein as a marker, they found that the degree of organ infectivity was similar regardless of the route of entry, and that tonsil tissue was the most strongly infected. In addition to expected concentrations of prion protein in the brain and spinal cord, it was also present in the autonomic nervous system, in peripheral nerves, and in Peyer's patches in the gut, suggesting possible risk of transmission from endoscopic procedures.
"In view of the high efficiency of transmission of the BSE agent to primates by the intravenous route, the latter should be regarded as a likely route of contamination for vCJD patients with a medical history involving a transfusion during the period at risk," the authors write.
"To avoid further contamination to human beings from peripheral tissues, the same precautionary measures taken for primary vCJD cases should apply to possible transfusion cases of the disease."