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Global Commentary
Wednesday, 12 October 2005
Head way to a healthy heart
Topic: Health
This Newsweek article, entitled "The Good Heart", adds to the notion that psychology is an important aspect of health.

The article reports that at a meeting of the American Heart Association last year, Debra Moser, a professor of nursing at the University of Kentucky in Lexington, presented the results of a study heart-attack patients with high anxiety levels were more likely to suffer complications than those low anxiety levels.

The article also cites Dr. Michael Frenneaux, professor of cardiovascular medicine at the University of Birmingham in England, as saying that depression doubles an otherwise healthy person's heart-attack risk, while for people who have suffered a heart attack in the past, depression quadruples or quintuples the risk of a second one.

Other factors in heart attack risk mentioned in the article include levels of hostility, depression, stress and childhood trauma. These seem to affect the body negatively through the release of stress hormones like cortisol and epinephrine (adrenaline), which lead to high blood pressure and blood-glucose levels. Stress hormones also cause inflammation, which is believed to promote heart disease through several stages, from plaque formation to heart attack.

The opposite of these negative emotions appears to help prevent or ameliorate heart disease. Psychologist Karen Matthews at the University of Pittsburgh found that optimism helped reduce thickening in the carotid arteries of postmenopausal women while Dr. Michael Miller of the University of Maryland School of Medicine found that laughter relaxed people's peripheral arteries and increased blood flow.

The findings reported in the article are interesting. They show that one way to a healthy heart is through the head.

However, the article probably does not cover the full range of mechanisms through which psychology affects heart health. For example, it does not mention the effect of stress on telomere shortening, an important ageing mechanism and therefore, surely an important factor in the development of heart disease.

Posted by lim_cs at 8:14 PM JST | post your comment (0) | link to this post
Monday, 29 August 2005
Coffee with antioxidants
Topic: Health
This is good news for coffee-lovers.

In its report entitled "Another Coffee Perk: Antioxidants", HealthCentral.com says:

By measuring the amount of antioxidants contained in the most common foods and beverages, and comparing them to U.S. government data on food consumption, researchers found that coffee far outpaced any other beverage or food as the main source of antioxidants in the American diet.

... [T]he average American received more than four times the amount of antioxidants from coffee daily than from black tea, which was second on the list. Bananas, dry beans and corn were the top three foods on the list.

However, Joe Vinson, the University of Scranton chemist who presented the results of his analysis yesterday at the annual meeting of the American Chemical Society, in Washington, DC, was also quoted in the report as saying that coffee has been linked to increased risk of cardiovascular disease and high blood pressure.

So the recommendation in mainstream health circles to rely more on fruits and vegetables for antioxidants still seems to be the more prudent one.

Posted by lim_cs at 10:56 AM JST | post your comment (0) | link to this post
Wednesday, 27 July 2005
Exercise cannot halt age-related effects on fitness
Topic: Health
A new study published in the American Heart Association journal Circulation shows that exercise cannot ward off the effects of ageing. Excerpt from the Associated Press report.

A treadmill test given to different age groups showed that as people aged, their aerobic capacity -- the amount of oxygen consumed while exercising -- declined at higher rates with each passing decade whether they exercised or not.

The researchers knew the rate of decline would worsen with age, but they were surprised by the magnitude, said Dr. Jerome L. Fleg, a cardiologist who is lead author of the study and a medical officer at the National Heart, Lung and Blood Institute in Maryland.

"I guess we were a little disappointed that regular exercise didn't make a difference in the rate of decline," he said.

However, he pointed out that those who exercise still end up ahead because their aerobic capacity was higher to begin with.

"If I start higher, I'm going to end higher," Fleg said. "Having a higher aerobic capacity translates into being more fit."
In my opinion, there is too much hope and hype involved in exercise. As the report points out, exercise can improve a person's health and fitness, but the deterioration in the body associated with ageing is an intrinsic process. It affects the body at a cellular and even genetic level -- see, for example, my previous posts on telomeres and ageing "Stress and ageing" and "Obesity and smoking affect biological age". While exercise causes the body to adapt closer to its capacity -- that is, it causes the body to become fitter -- that capacity -- the maximum fitness that the body can attain -- itself declines with age.

The idea in some that exercise can arrest or reverse that age-related decline in fitness capacity was always a bit of wishful thinking.

Posted by lim_cs at 11:47 AM JST | post your comment (0) | link to this post
Tuesday, 14 June 2005
Obesity and smoking affect biological age
Topic: Health
A new study has provided yet more evidence that telomeres play a fundamental role in translating risk factors into age-related diseases.

Telomeres are the material which cap the ends of the chromosomes in cells and protect them from damage. Every time a cell divides -- and as people age -- the telomeres get shorter.

The new study involved more than 1,100 British women aged between 18 and 76 years. The women filled out a questionnaire on their smoking history and provided blood samples, which were tested for concentrations of a body fat regulator called leptin and for telomere length.

As HealthDay News reports, the study found that:

...telomeres of obese women and smokers were much shorter than those of lean women and those who'd never smoked. In contrast, lean women had much longer telomeres than moderately overweight women who, in turn, had longer telomeres than obese women.
The net effects:

Overall, obese women aged an additional 8.8 years -- based on telomere length -- compared to lean women, the researchers reported. A current or previous history of smoking entailed an average 4.6 year increase in aging compared to never-smokers, while those with long-term smoking habits -- a pack-a-day for 40 years -- added an additional 7.4 years of aging to their life compared to those who stayed away from cigarettes completely, the study found.
For another post on research involving telomeres, see "Stress and ageing".

Posted by lim_cs at 12:02 PM JST | post your comment (0) | link to this post
Wednesday, 18 May 2005
Diet affects recurrence of breast cancer
Topic: Health
A new study has found that postmenopausal breast cancer survivors who cut down on fats in their diet can reduce their risk of tumor recurrence.

WebMD reports the following details on the study:

The study included 2,437 women aged 48 to 75. All were treated with surgery for breast cancer, followed by radiation, chemotherapy, and hormone treatment, if needed. Every three months, they received some general dietary guidance.

Nearly 1,000 of the women were also entered into an intensive nutrition program... Women who received the intensive counseling reduced the amount of fat in their diet from 51 grams per day to about 33 grams a day, or from 29% to 21% of their total daily calories.
And the results:

At five years, less than 10% of those on the low-fat diet had their cancer recur. Twelve percent of the women who continued on their usual diet had cancer recurrence during this time. This translates to about a 24% reduction in risk, [researcher Rowan T] Chlebowski says.

Most breast cancers are fueled by estrogen, and because of this several treatments are available that block hormones to the breast and reduce the risk of recurrence.

Women whose tumors were not fueled by hormones -- a high-risk group that account for about 30% of women with breast cancer -- benefited the most. Their chances of recurrence fell by about 42% when limiting dietary fats.
This study just adds to the growing body of evidence that diet has an important role in the incidence of cancer. There are two caveats, though.

First of all, although the women on the low-fat diet benefited as a group, the researchers are not clear on whether the benefit was derived from the low amount of fat consumed or from other factors -- for example, weight loss, increase in fibre consumption.

Secondly, for the study subjects a whole -- as opposed to just those women whose tumours were not fueled by hormones -- the recurrence rate dropped from 12 percent for those on their usual diet to 10 percent for those on the low-fat diet -- all of 2 percentage points.

More studies on this would certainly be helpful.

Posted by lim_cs at 12:29 PM JST | post your comment (0) | link to this post
Thursday, 28 April 2005
Vitamin D, calcium supplements not helpful in osteoporosis
Topic: Health
Two new studies carried out in the United Kingdom have found that taking vitamin D or calcium supplements does not help prevent fractures in elderly people.

In one study, researchers led by University of Aberdeen professor Adrian Grant randomly assigned 5,292 people over 70 who had already suffered a fracture either to take a dummy pill, a daily supplement of vitamin D, calcium or both supplements together. They were then tracked for between 24 and 62 months.

The researchers found that 13 percent of the patients had a new fracture. For people in the group taking calcium, the fracture rate was 12.6 percent, compared with 13.7 percent of those taking a dummy pill. For those taking vitamin D alone, the fracture rate was 13.3 percent, compared with 13.1 percent for those taking the dummy pill. And for those taking both calcium and vitamin D, the fracture rate was 12.6 percent, compared with 13.4 percent for those taking the dummy pill.

The researchers concluded that supplements do not offer protection from second fractures.

This study appears in the April 27 online issue of The Lancet.

In the second study at the University of York, researchers tracked 3,314 women aged 70 and older. Half were given calcium and vitamin D tablets to take daily, the rest just received a leaflet on diet and prevention of falls. All women were monitored for an average of about two years.

The researchers found that about 1 percent of women in both groups suffered a subsequent hip fracture. The researchers concluded that there was no reduction in hip fractures with either calcium or vitamin D.

This study appears in the April 30 issue of the British Medical Journal.

An expert interviewed by HealthDay saw nothing new in The Lancet study. "I am not surprised," said Dr. Steven J. Goldstein, a professor of obstetrics and gynecology at New York University Medical Center. "By definition, the people they studied here had osteoporosis."

"We know that vitamin D and calcium alone are not sufficient to treat osteoporosis," Goldstein added. "All this study showed is that if you take people who have already suffered a fracture, who therefore by definition have osteoporosis, and you simply treat them with calcium and vitamin D, it's not sufficient. You've already let the horse out of the barn."

Goldstein pointed out that the time to take vitamin D and calcium is when you are young.

Posted by lim_cs at 11:45 AM JST | post your comment (0) | link to this post
Thursday, 21 April 2005
Obesity and mortality
Topic: Health
A new study has found that obesity is not as dangerous as previously thought.

Researchers from Centers for Disease Control and Prevention (CDC) have found that both obesity and being underweight are associated with excess deaths when compared with the normal weight population.

There were 112,000 more deaths than expected among obese individuals, that is, those with body mass index (BMI) of 30 or higher. Among underweight individuals -- those with BMI of less than 18.5 -- there were nearly 34,000 more deaths than expected. However, while most of the excess deaths among the underweight occurred in people age 70 or older, most of the excess deaths among the obese occurred in people younger than 70.

Being slightly overweight -- BMI of 25-29.9 -- was not associated with excess mortality. In fact, the study found 87,000 fewer deaths than expected among those in this BMI range.

Another study by researchers from CDC found that cardiovascular disease risk factors in the US have declined, regardless of BMI. The exception was diabetes, which has increased by 55 percent over the past 40 years.

These studies appear in the 20 April 2005 issue of Journal of the American Medical Association (JAMA).

Most reports on the study linking obesity and mortality have highlighted the fact that it shows that the risk of death from being overweight has been overestimated. Times Online, however, entitled its report on the study "If you want to live longer - put on weight". This seems unwarranted.

First of all, whether putting on weight is healthy depends on your starting weight. Obesity is still associated with higher death risk.

Secondly, it may be premature to make recommendations based on this study. No one study can be conclusive. The findings need to be replicated in other studies to eliminate the possibility of flaws in the study. With so many factors affecting health and mortality rates, failure to properly account for any factor can have an impact on the overall result. After all, CDC itself had earlier put out a report that predicted a much higher mortality rate from obesity, which, in the light of the findings from the new study, is leading to some controversy in the United States (see the report "Stonewalling: Why Won’t The CDC Endorse New Obesity Deaths Figure?")

In any case, as the Times Online itself wrote, quoting Nigel Hawkes, The Times health editor: "Despite its breadth, the conclusions of the report are limited. It looked only at deaths, not at disease or disability which generally increase with weight".

Posted by lim_cs at 3:25 PM JST | post your comment (0) | link to this post
Wednesday, 20 April 2005
Happiness brings health
Topic: Health
A new study has found that happiness may bring health.

Researchers from University College London tested 116 men and 100 women who were taking part in a major study of thousands of London-based civil servants to investigate the risk factors for coronary heart disease. The researchers evaluated the level of happiness of the subjects during the course of the day.

The researchers found that levels of cortisol -- a stress hormone related to conditions including type II diabetes and high blood pressure -- were 32 percent lower in people who reported more happy moments. Happy people also had lower levels of plasma fibrinogen -- a marker for inflammation and an indication of heart disease -- when they were stressed.

The research is published in the Proceedings of the National Academy of Sciences. The BBC and WebMD carry reports on the study.

By focusing on happiness, this study complements some others that find that psychological distress adversely affects health -- see for example "Stress and ageing".

Posted by lim_cs at 12:12 PM JST | post your comment (0) | link to this post
Friday, 24 December 2004
Limits to the benefits of exercise
Topic: Health
It's Christmas Eve and if you are planning to go out and celebrate tonight and over the next week or so by feasting, do note that some new research suggests that if you gain any weight in the process, don't assume that exercise will be able to undo the damage.

Early this month, the BBC put out a report which said that exercise benefits vary widely among individuals. The report cited a Louisiana University study in which researchers put 742 people through a strenuous 20-week endurance training programme.

Over the course of the programme, measures such as oxygen consumption improved in some, but not in others. While the average maximum oxygen consumption improved by 17 percent, some participants improved by 40 percent while another group showed no improvement at all.

Similar patterns were seen when other fitness measures such as cardiac output, blood pressure, heart rate were checked, as well as for insulin resistance, a marker of risk for heart disease and diabetes.

Mark Hargreaves, of Deakin University, Melbourne, was quoted in the report as saying: "We need to recognise that, although on average exercise may have clear benefits, it may not work for everyone. Some people may do better to change their diet."

Which leads to another BBC report today. This report cited a study by a group of Harvard School of Public Health researchers on more than 116,000 women nurses which found that physical activity did not totally compensate for the higher death risk associated with being obese.

The researchers estimate that excess weight and physical inactivity together could account for about a third of all premature deaths, two-thirds of deaths from cardiovascular disease, and a fifth of deaths from cancer among non-smoking women.

They defined excess weight as a body-mass index (weight in kg divided by the square of the height in meters) of 25 or more. Women who did more than 3.5 hours per week of exercise were considered "active".

Lean women who exercised less than 3.5 hours per week increased their risk of early death by 55 percent. Obese women who worked out for at least 3.5 hours a week increased their risk by 91 percent and those who were obese and inactive increased their risk of a premature death by 142 percent.

The researchers said the key to a long life, for both men and women, is to keep weight down and take regular exercise.

And if you can't help bingeing over the next week of festivities, you can at least take that as a New Year resolution.

Posted by lim_cs at 2:35 PM WST | post your comment (0) | link to this post
Friday, 3 December 2004
Stress and ageing
Topic: Health
It is commonly believed that stress accelerates ageing. Scientists have new evidence that this is indeed so.

A team from the University of California at San Francisco has found that the stress of caring for a sick child can add about 10 or more years to the biological age of a woman's cells. It does this by affecting key pieces of DNA called telomeres which are involved in regulating cell division, they say.

Telomeres are strips of DNA at the end of chromosomes which appear to protect and stabilise the chromosome ends. However, they shorten each time a cell divides, until there is nothing left, making the cell more defect-prone after division and increasing the risk of age-related disorders. The tendency for telomeres to shorten at cell division can be mitigated by an enzyme called telomerase, which helps to regenerate the ends.

The study examined 58 women, which included 39 healthy, pre-menopausal women who were primary caregivers for a child with a chronic illness, and 19 age-matched mothers of healthy children who served as a control group.

All the women completed questionnaires asking them to evaluate the level of stress they felt they had been under during the previous month. Blood samples were also taken so scientists could carry out DNA analysis of telomeres. Levels of telomerase in immune cells were also measured.

There was no difference in the telomere length of the two groups. However, in the 14 women with the highest stress scores, telomeres averaged 3,110 units in length; the 14 with the lowest stress had telomeres that averaged 3,660 units. The scientists translate this shortening to 9 to 17 additional years of ageing.

Within the care-giving group, the longer that a woman had been a care-giver, the shorter was the length of telomeres.

The higher-stress group was also found to have lower levels of telomerase in immune cells. The researchers, led by Dr Elissa S. Epel, said this implied the immune cells could function less well and could die sooner.

It was also found that the high-stress women also had higher oxidative stress levels -- cumulative damage caused by molecules called "free radicals" -- which has been shown to speed up the shortening of telomeres in other studies.

The researchers were not able to say exactly how stress affects telomeres, but suggested that their findings showed how cellular aging could be a way in which psychological stress was linked to the earlier onset of age-related diseases.

This study has been published in the Proceedings of the National Academy of Sciences. It represents an important step towards the recognition among health experts that psychological health plays an important part in physical health.

Posted by lim_cs at 10:49 AM WST | post your comment (0) | link to this post

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