Tips from gaining health

Regular aspirin use appears to be associated with an increased risk of neovascular age-related macular degeneration (AMD), which is a leading cause of blindness in older people, and it appears to be independent of a history of cardiovascular disease and smoking, according to a report published Online First by JAMA Internal Medicine.

Aspirin is one of the most widely used medications in the world and is commonly used in the prevention of cardiovascular disease, such as myocardial infarction (heart attack) and ischemic stroke. While a recent study suggested that regular aspirin use was associated with AMD, particularly the more visually devastating neovascular (wet) form, other studies have reported inconsistent findings. Smoking is also a preventable risk factor for AMD, the authors write in the study background.

Gerald Liew, Ph.D., of the University of Sydney, Australia, and colleagues examined whether regular aspirin use (defined as once or more per week in the past year) was associated with a higher risk of developing AMD by conducting a prospective analysis of data from an Australian study that included four examinations during a 15-year period. Of 2,389 participants, 257 individuals (10.8 percent) were regular aspirin users.

After the 15-year follow-up, 63 individuals (24.5 percent) developed incident neovascular AMD, according to the results.

"The cumulative incidence of neovascular AMD among nonregular aspirin users was 0.8 percent at five years, 1.6 percent at 10 years, and 3.7 percent at 15 years; among regular aspirin users, the cumulative incidence was 1.9 percent at five years, 7 percent at 10 years and 9.3 percent at 15 years, respectively," the authors note. "Regular aspirin use was significantly associated with an increased incidence of neovascular AMD."

The authors note that any decision concerning whether to stop aspirin therapy is "complex and needs to be individualized."

"Currently, there is insufficient evidence to recommend changing clinical practice, except perhaps in patients with strong risk factors for neovascular AMD (e.g., existing late AMD in the fellow eye) in whom it may be appropriate to raise the potentially small risk of incident neovascular AMD with long-term aspirin therapy," the authors conclude.

Commentary: Relationship of Aspirin Use with Age-Related Macular Degeneration

In an invited commentary, Sanjay Kaul, M.D., and George A. Diamond, M.D., of Cedars-Sinai Medical Center, Los Angeles, write: "This study has important strengths and limitations. It provides evidence from the largest prospective cohort with more than five years of longitudinal evaluation reported to date using objective and standardized ascertainment of AMD."

"The key limitation is the nonrandomized design of the study with its potential for residual (unmeasured or unobserved) confounding that cannot be mitigated by multivariate logistic regression or propensity score analysis," the authors continue.

"From a purely science-of-medicine perspective, the strength of evidence is not sufficiently robust to be clinically directive. These findings are, at best, hypothesis-generating that should await validation in prospective randomized studies before guiding clinical practice or patient behavior," the authors conclude. "However, from an art-of-medicine perspective, based on the limited amount of available evidence, there are some courses of action available to the thoughtful clinician. In the absence of definitive evidence regarding whether limiting aspirin exposure mitigates AMD risk, one obvious course of action is to maintain the status quo."

A University of Eastern Finland study showed that low serum vitamin D levels are a risk factor for pneumonia. The risk of contracting pneumonia was more than 2.5 times greater in subjects with the lowest vitamin D levels than in subjects with high vitamin D levels. The results were published in Journal of Epidemiology and Community Health.

The follow-up study carried out by the UEF Institute of Public Health investigated the link between serum vitamin D3 and the risk of contracting pneumonia. The study involved 1,421 subjects living in the Kuopio region in Eastern Finland. The serum vitamin D3 levels of the subjects were measured from blood samples drawn in 1998–2001, and these data were compared against reported cases of pneumonia in hospital records in the same set of subjects in 1998–2009. The results showed that during the follow-up, subjects with serum vitamin D3 levels representing the lowest third were more than 2.5 times more likely to contract pneumonia than subjects with high vitamin D3 levels. Furthermore, smoking constituted a significant risk factor for pneumonia. The risk of contracting pneumonia also grew by age, and was greater in men than women. At baseline, the mean serum D3 concentration of the study population was 43.5 nmol/l, and the mean age of the study population was 62.5 years.

Earlier research has shown that vitamin D deficiency weakens the immune defence system and increases the risk of mild respiratory infections. This University of Eastern Finland study was the first one to establish that vitamin D deficiency also increases the risk of contracting pneumonia in the ageing general population. According to the researchers, this finding supports earlier observations on the diverse role of vitamin D in the body, and it also calls for further research on vitamin D deficiency as a public health issue. In northern latitudes, there is enough sun exposure to maintain sufficient vitamin D levels in summer, but not during the winter season, and vitamin D supplementation is often required.

New research from the University of Reading has shown that eating four slices of bread containing beetroot lowers blood pressure and improves the function of blood vessels, significantly improving heart health.

The researchers provided 24 participants with four slices (200g) of bread containing 100g of beetroot, or control bread with no beetroot enrichment once on two separate occasions. They found the diastolic¹ blood pressure of those who consumed ‘beetroot bread was lowered by up to 7 mmHg when compared to the control group approximately 3 hours after consumption.

Evidence suggests that a reduction in diastolic blood pressure of 5-6 mmHg over a five year period could reduce the chances of a stroke by 38% and coronary heart disease by 23% less. In addition, prolonged high blood pressure is an important risk factor for the development of heart disease, which is the single biggest killer in the UK, causing nearly 179, 000 deaths per year.

The component of beetroot bread thought to be responsible for the beneficial effects on blood vessel function and blood pressure is dietary nitrate. Dietary nitrate is a natural component of beetroot and a number of other vegetables such as spinach, lettuce and rocket.

When dietary nitrate is eaten it produces nitric oxide in the blood vessel wall which causes relaxation of the vessel and increased blood flow. This ultimately results in lowering of blood pressure and an improvement in blood vessel function.

Julie Lovegrove, Professor of Human Nutrition, Head of the Hugh Sinclair Unit of Human Nutrition and the Deputy Director of the Institute for Cardiovascular and Metabolic Research (ICMR) at the University of Reading, who led the study said: "These exciting and novel findings show for the first time that bread containing beetroot improves blood vessel function. This is an important addition to the increasing body of evidence that suggests beneficial effects of dietary nitrate rich foods on the heart.

"This research also supports the findings of our previous study which was carried out last year and showed that beetroot in the form of juice or bread lowers blood pressure. Collectively, these studies suggest a potential role for foods rich in dietary nitrate in the management of high blood pressure."

The study, published in the Journal of Nutrition, was undertaken by Dr Ditte Hobbs in the University of Readings Hugh Sinclair Human Nutrition Group, which has an international reputation for its research into the relationship between diet and the risk of chronic disease such as cardiovascular disease, diabetes, neurodegenerative disease and cancer.

Research due in an upcoming issue of the British Medical Journal found that smokers had a greater risk of developing glucose intolerance than people who never smoked. But another finding of the study is raising eyebrows - that people exposed to secondhand smoke also experienced an increased risk for the condition.

The study, begun in 1985, followed 4,572 young men and women (age 18 to 30 at baseline) in four American cities for up to 15 years.

After adjusting for confounders (factors that could also influence development of glucose tolerance - age, sex, race, education, income, blood pressure, body mass index, triglycerides, and alcohol intake), researchers found, when compared to people who never smoked and had no passive smoke exposure:

• Current smokers (average 10 cigarettes/day) had a 65% greater risk of developing prediabetes.
  
• People who never smoked but were exposed to secondhand smoke (average 12.6 hours/week) had a 35% greater risk of developing prediabetes.

Prediabetes, also known as impaired glucose tolerance, was recorded when serum glucose ≥ 100 mg/dl and < 126 mg/dl. (Diabetes is diagnosed when fasting serum glucose ≥ 126 mg/dl.) Most people with prediabetes will develop full blown diabetes unless they make lifestyle changes.

Researchers said substances in cigarette smoke which are damaging to the pancreas may be present in higher concentrations in secondhand smoke, since passive smoke is produced under different temperatures and chemical conditions.

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Some news summaries:
Secondhand Smoke Linked to Diabetes Risk

Passive Smoke Could Prompt Diabetes Precursor: Report

Smoking Linked to Glucose Intolerance in Young Adults

For the study abstract:
Active and passive smoking and development of glucose intolerance among young adults in a prospective cohort: CARDIA study

For the study (pdf):
Active and passive smoking and development of glucose intolerance among young adults in a prospective cohort: CARDIA study

My previous post discussed the link between smoking and death from heart and lung diseases (and showed benefit for quitting). Heres a study, actually a study of studies or a meta-analysis, from 5 months ago that reasserted the often observed link between smoking and type 2 diabetes:

Active Smoking and the Risk of Type 2 Diabetes, JAMA, December, 2007

Of the 25 studies included in this analysis, 24 reported a positive association between smoking and diabetes, specifically:

"The pooled adjusted RR was 1.44."

An RR (Relative Risk) of 1.44 means that there was a 44% increased risk for developing diabetes among active smokers vs. non-smokers. Among heavy smokers, the risk increased to 61%:

"The risk of diabetes was greater for heavy smokers (≥20 cigarettes/day; RR 1.61) than for lighter smokers (RR 1.29) and lower for former smokers (RR 1.23) compared with active smokers, consistent with a dose-response phenomenon."

The link was so consistent that the authors stated there was "no need for further cohort studies to test this hypothesis." They recommended instead "that future studies focus on plausible causal mechanisms or mediating factors such as obesity, lack of physical activity, dietary habits, and stress levels."

One mechanism they noted which has appeared in previous studies is smokings link to insulin resistance or inadequate insulin secretion - a mechanism which should bear scrutiny in future investigations.
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Sibling attacked by Stroke| The debate on whether the stroke hereditary disease or not, is still growing. But the latest research by Swedish scientists found evidence that risk of stroke can be seen from absence of siblings who have a history of stroke.

Researchers reported that individuals who have a sibling male or female with a stroke, the risk of stroke could rise to 64 percent than those who do not have a family history of stroke.

In fact, increasing the risk of stroke may be higher if a person has a sibling with a stroke when she was still relatively young. For example, when your brother had a stroke before the age of 56 years, then their siblings (brother or sister) have an increased risk of stroke nearly doubled.

The findings refer to the most common type of stroke - called ischemic stroke - which occurs when blood flow to the brain is interrupted as a result of blockages in blood vessels.

"Patients in zone of risk of heart attack or stroke should be made aware that genetic factors contribute greatly," says study leader, Dr. Erik Ingelsson, a professor of cardiovascular epidemiology at the Karolinska Institute, Stockholm.

To find out how relationships between family history and risk of stroke, researchers included more than 30 700 men and women that his brother had suffered a stroke and 152 000 adults who have siblings with no history of stroke.

The result, those who have a brother or sister with a history of stroke (61-64 percent) were more likely to suffer a stroke than people without a family history of stroke.

While individuals who have a sibling with a stroke at age 55 years or younger nearly doubled risk of stroke. Gender differences also seem to not be too influential.

Researchers emphasize that they only saw limited incidence of stroke and did not see the other risk factors like high blood pressure or cholesterol levels. This means that researchers can not track the extent to which genetic factors influence the risk of stroke.

"But if your brother had a stroke, probably the best idea is to pay more attention to lifestyle habits such as diet and exercise, and blood pressure checked regularly," advises Ingelsson.

Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, said the study was very helpful in better understanding about the risk of stroke. "It gives us insight into the family of risk, involving both genetic, in the case of high blood pressure and risk of high cholesterol, and lifestyle history together," he said.

"Obviously, those who have relatives with stroke have a higher risk, and should strive to address all modifiable risk factors for stroke," added Fonarow.

Dr. Murray Mittleman, director of cardiovascular epidemiology research unit of the Beth Israel Deaconess Medical Center, Boston, said, although one can not eliminate the factor of family history, but they can control the risk through lifestyle interventions.

"That means stop smoking if you are a smoker. Routine blood pressure checks, maintain an active lifestyle. And choose foods that nourish the heart to maintain a good balance of healthy fats, fresh fruits and vegetables, as well as a reasonable amount of fiber," Mittleman clear.