Author: Tony Wagner

Children’s blood pressure is rising

In the May 5 2004 issue of The Journal of the American Medical Association, a US study has found the rise in childhood obesity may also be partly responsible for a rise in children’s blood pressure. This may have a bearing on the children’s future health as high blood pressure increases the risk of heart disease and stroke in later life.

Below we look at the issue in more depth:

What did the study find?

The US study looked at 3,496 US children aged 8 to 17 years in 1988-1994 and compared their blood pressure to 2,086 US children of the same age in 1999-2000.

The researchers measured the children’s:

  • diastolic blood pressure – the pressure in the arteries when the heart is pumping blood
  • systolic blood pressure – the pressure in the arteries between heart beats when blood is not being pumped

The average systolic blood pressure for the children was 104.6mmHg in 1988-1994 and this rose to 106mmHg in 1999-2000.

The average diastolic blood pressure for children in 1988-1999 was 58.4mmHg and this rose to 61.7mmHg in 1999-2000.

In other words, children’s systolic blood pressure had risen by an average of 1.4 mmHg and their diastolic blood pressures had risen by an average of 3.3mmHg.

Why is this seen as important?

Having high blood pressure in later life raises the risk of developing heart disease and stroke. High blood pressure is defined as having a systolic blood presure of 140 or more and/or a diastolic blood pressure of 90 or more.

The children’s average blood pressure does not suggest that they will have high blood pressure soon. However, blood pressure rises with age and the fact that children have higher blood pressure than previous children means that they are at more at risk of developing the problem in the future. One of the study’s researchers, Dr Jeffrey Cutler, said: “The increases found by the study in children’s average blood pressures may seem small, but they can have serious consequences.”

Dr Cutler claimed that previous research suggests that every 1-2mmHg rise in children’s systolic blood pressure increases their risk of developing high blood pressure by 10 percent. Therefore, the children studied in 1999-2000 had an average increased risk of high blood pressure in later life of 14 percent when compared with those children studied in 1988-1994.

What is thought to be responsible for this rise in blood pressure?

The researchers believe that part of the rise in children’s blood pressure is partly due to the rise in the numbers of children who are overweight or obese. In fact, the researchers have calculated that 29 percent of the rise in systolic blood pressure and 12 percent in the rise in diastolic blood pressure could be attributed to the increase in children’s weights.

According to previous research, the percentage of boys who were overweight had risen from 11.3 percent in 1988-1994 to 15.5 percent in 1999-2000. While the percentage of girls who were overweight had risen even more dramatically from 9.7 percent in 1988-1994 to 15.5 percent in 1999-2000.

Apart from being overweight or obese, the other main lifestyle factors that contribute to increased blood pressure are not getting enough physical activity and eating too much salt in the diet.

Could UK children’s blood pressure also be higher than previous generations?

The levels of childhood overweight and obesity are increasing in the UK, so it is more than likely that UK children’s blood pressure are also higher than previous generations.

Both Professor Graham MacGregor, chairman of the Blood Pressure Association, and Belinda Linda, head of medical information at the British Heart Foundation agree that the rise in UK children’s weights will mean that their blood pressure will be higher too. They are concerned that will lead to higher rates of high blood pressure in later life.

What can be done to reduce childhood obesity and children’s blood pressures?

Reduce the amount of salt in the daily diet

Many children eat more than the recommended daily amount of salt in their diet (see table below). Two of the main contributors to this are the salt found in processed foods (for example ready meals and crisps) and salt that is added while cooking.

D A I L Y    S A L T    L E V E L S
The UK Government’s Scientific Advisory Committee on Nutrition (SACN) recommends the following daily salt intakes:
Baby aged up to six months oldless than 1g per day
Baby aged 7-12 months1g per day
Child aged 1-6 years2g per day
Child aged 7-14 years5g per day
Adult (aged 14+ years)a maximum of 6g per day

Make sure children get at least 60 minutes of physical activity every day

The UK Government now recommends that all children (up to teenage) should be physically active for at least 60 minutes per day, every day of the week. This activity can be built up through the day in bouts of 10 minutes or more, which means that it is possible to incorporate this activity more easily into daily life. For example, the Government suggests children could build this up by:

  • playing in break times at school
  • walking or cycling to and from school
  • taking part in organised activities such as PE, sports and swimming
  • playing with friends near home

However, it is also important for children to develop strong bones, it is vital that children engage in activities that build healthy bones at least twice a week. Activities such as running, jumping, ball games and gymnastics are ideal for strengthening bones. In addition, muscle strength and flexibility can be developed through activities such as carrying, climbing and rough and tumble.

This level of activity will also help children to keep their weight under control.

Parents can encourage healthy lifestyles in their children

If parents set good role models for their children, by eating healthily, not cooking with salt or adding it at the dinner table, and by being physically active in their daily lives, their children are more likely to adopt these lifestyle habits as well.

Acupuncture cuts migraines

British doctors have found that acupuncture can reduce the number of days of migraine a person has a year, as well as reducing the amount of medication they need and days off work. The results of their study are published on the website of the British Medical Journal.

How did the study work?

The study was designed to look at the use of acupuncture as an option for GPs prescribing treatment for migraines and tension-type headaches. GPs randomly offered their patients either standard treatment (medication and GP advice) or standard treatment plus acupuncture. Those who received acupuncture had up to 12 acupuncture sessions over the space of three months.

How many people were studied?

The doctors identified 401 people with chronic headache, most of them had migraines while the others had tension-type headaches. All the people were aged 18-65 years old and had an average of at least two headaches a month.

What were the results?

At the end of 12 months, people who had acupuncture in addition to standard treatment had 34 percent less severe headaches than people who only received standard treatment. Before treatment, the acupuncture group had a mean weekly headache score of 24.6 which fell to 16.2 after 12 months. The group that recieved only standard treatment had a weekly headache score of 26.7 before treatment and a score of 22.3 after 12 months.

During the 12-month study, people who had acupuncture in addition to standard treatment reported 15.6 days of headache during the four weeks before treatment and only 11.4 days of headache in four weeks at the end of the 12-month period. In contrast, those people who received standard treatment only reported 16.2 days of headache in the four weeks before treatment and 13.6 days of headache in four weeks at the end of the 12-month period.

These results mean that the people who recieved acupunture with standard treatment had 1.8 days less of headache every four weeks, when compared with those who did not have acupuncture. This works out as 21.6 days less of headache a year.

Over the 12-month period of the study, people who received acupuncture with standard treatment took a mean number of 12.6 days off from work (standard deviation of 18.9 days). In comparison, the standard treatment only group took 13.8 days off from work (standard deviation of 16.2 days). When these results were analysed statistically, the result is that the acupuncture group took 15 percent less days off work.

How were these results measured?

People filled in a headache diary for four weeks before their treatment started. They then repeated this at three months and one year after starting treatment. They were asked to assess the severity of their headache on a six-point scale four times a day. These scores were added together to give a daily headache score.

In addition, people filled in questionnaires that measured their use of headache treatments and days off sick from work.

What does this mean?

Most doctors agree that acupuncture can play a useful role in reducing pain from headaches but, up until now, the evidence has not been conclusive. This study provides further evidence for the benefits of acupuncture as a treatment for migraine. This is because the study was controlled, the people studied were randomly assigned to either standard treatment or standard treatment plus acupuncture, and the study involved a sizeable number of people.

In addition, the study also shows that acupuncture appears to offer long-lasting benefits. Most of the acupuncture group only received acupuncture for the first three months of treatment, yet their headache severity scores were significantly lower than those for standard-treament only when measured a full nine months after acupuncture treatment had stopped.

What do the study’s authors believe this study shows?

The authors of this study believe that the results show that the use acupuncture in addition to standard treatment leads to persisting, clinically useful benefits for people with chronic headache, particularly migraine. They argue that acupuncture should be used more widely to treat headaches.

Strict diet lowers heart risk

A small-scale study in the US has shown that a stringent calorie-restricted diet may produce large reductions in heart disease and diabetes risk.

The researchers, from the Washington University School of Medicine, St Louis, studied the effects following a calorie-restricted diet of between 10-25 percent less calorie intake than the average western diet. The study appeared in the online version of the journal The Proceedings of the National Academy of Sciences on 19 April and will be published in the 27 April 2004 edition. It offers further support to idea that eating a varied, balanced diet and staying at a healthy weight by being physically active will help to lower your risk of developing heart disease.

What is a calorie-restricted diet?

A calorie-restricted diet is one where a person eats 10-25 percent less calories than an average western person. In this study, the calorie-restricted diet individuals ate 1,112-1,958 kcal/day of energy.

Because there is the danger that people following such a diet might not get the full range of vitamins and minerals they need, individuals following a calorie-restricted diet eat nutrient-dense foods. To do this they eat a wide variety of vegetables, fruits, nuts, dairy products, egg whites, wheat and soy proteins and meat. In this way, they ensure that they get more than 100 percent of their RDI (recommended daily intake) for all essential vitamins and minerals.

In addition to a restricted calorie intake, the people avoid all processed foods containing trans-fatty acids and refined carbohydrates in the form of desserts, snacks and soft drinks.

How does a calorie-restricted diet compare with a normal western diet?

The average american takes in almost twice as much energy as a calorie-restricted dieter: roughly 1,976-3,537 kcal/day.

Also, because the average american diet contains less fruit and vegetables and more processed foods than a calorie-restricted dieter, the composition of what an average american eats is different too.

Normal american diet:
Total energy intake – 18 percent protein, 32 percent fat, 50 percent carbohydrates.

Calorie-restricted diet:
Total energy intake – 26 percent protein, 28 percent fat, 46 percent complex carbohydrates.

Why do some people follow a reduced-calorie diet? What benefits do they believe they will gain?

Some people believe that calorie-restricted diets will confer a longer life-expectancy and help to counter the effects of ageing.

These beliefs are based on the results of animal studies that show that calorie reduction can increase life expectancy by up to 30 percent. So far, these studies have been carried out in rats, mice, fish, worms and various insects.

These findings also have support from an observation during the Second World War. During the war some of North European countries experienced a food shortage and this resulted in rationing. In some of these countries, rationing was accompanied with a sharp fall in mortality from coronary artery disease (heart disease). When the war ended, mortality from coronary artery disease rose sharply.

For these reasons, a small number of individuals have been following calorie-restricted diets for a number of years to try to extend their lifespans beyond the usual range.

What were the researchers aiming to achieve with this study of calorie-restricted dieting?

The researchers wanted to conduct the first human study into the effects of a calorie-restricted diet. They were particularly interested in finding out whether or not such a diet really did have an effect on a person’s risk of developing heart disease.

One of the main causes of heart disease (and strokes) is the narrowing of a person’s arteries through a process called atherosclerosis. Atherosclerosis is the plaque build up on the arterial walls that can impair blood flow and leads to formation of a clot, which can cause a heart attack or a stroke. It is the leading cause of death in the western world.

For this reason, the researchers decided to measure the individual’s risk of developing atherosclerosis. To do this, they measured a person’s risk factors for this condition.

What are the risk factors for developing atherosclerosis?

Link between drinking alcohol and gout

There are a number of risk factors for atherosclerosis, and many of them can be reduced by eating a healthy, balanced diet and being physically active.

The risk factors for developing atherosclerosis are:

  • being overweight or obese (having a body mass index – BMI – of more than 25)
  • high total cholesterol levels
  • high levels of LDL (bad) cholesterol
  • low levels of HDL (good) cholesterol
  • high ratio of total cholesterol to HDL cholesterol
  • high triglyceride levels
  • high blood pressure

How was the study carried out?

The researchers decided to measure the risk factors for atherosclerosis in people who had been following a calorie-restricted diet for a number of years and compare them with those of people following a normal american (or western) diet. The researchers were interested to see if the people following a calorie-restricted diet had lower levels (and hence lower risk of atherosclerosis) than healthy people who ate a normal western diet.

Who was studied?

The study followed 18 individuals from Caloric Restriction Optimal Nutrition Society who were following calorie-restricted diets. They were aged 35-82 years old, with an average age of 50 years. They had been following calorie-restricted diets for 3-15 years, the average length of time was 6 years. None of them were smokers and none were taking medicines that would affect their blood pressure or cholesterol levels.

To compare the calorie-restricted dieters to people eating a normal western diet, the researchers used a comparison group of 18 healthy americans. These 18 people were matched against the 18 calorie-restricted dieters for age and socioeconomic status.

Could the effect of starting a calorie-restricted diet on an individual be followed?

Another interesting part to this research was that the effect of starting and then following a calorie-restricted diet could be studied. The researchers discovered that 12 of the calorie-restricted diet individuals had medical data for their blood pressure, serum lipid levels and lipoprotein levels from the time before they started calorie restriction. These levels could be compared with the results of starting and then maintaining a calorie-restricted diet.

All 12 individuals had levels that were similar to normal americans before starting calorie-restricted diets. After starting a calorie-restricted diet, all 12 experienced their greatest changes in blood pressure, serum lipid levels, lipoprotein levels and weight loss in the first year of dieting. These levels were then maintained or decreased further with continued calorie restriction.

How did calorie restriction affect body mass index (BMI)?

Body mass index (BMI) was significantly lower in the calorie-restricted group when compared with the matched group; 19.6 compared with 25.9. The BMI values for the comparison group are similar to the mean BMI values for middle-aged people in the US.

All those on calorie-restricted diets experienced reductions in BMI after starting their diet. Their BMIs decreased from an average of 24 (range of 29.6 to 19.4) to an average of 19.5 (range of 22.8 to 16.5) over the course of their dieting (3-15 years). Nearly all the decrease in BMI occurred in the first year of dieting.

How did calorie-restriction affect cholesterol and triglyceride levels?

It was found that the average total cholesterol and LDL (bad) cholesterol levels for calorie-restricted individuals were the equivalent of those found in the lowest 10% of normal people in their age group.

It was found that the average HDL (good) cholesterol levels for calorie-restricted individuals were very high – in the 85th to 90th percentile range for normal middle-aged US men.

Because of these very healthy results, calorie-restricted dieters had remarkably low total cholesterol to HDL cholesterol ratios, a very positive sign for lowering the risk of heart disease.

These positive changes in calorie-restricted individuals were found to occur mainly in the first year of dieting. When the levels of the 12 individuals who had information for their cholesterol levels before they began a calorie-restricted diet were studied, it was found that they had close to average levels for normal middle-aged americans. However, following the calorie-restricted diet brought about large improvements in cholesterol levels and most of this occurred in the first year of dieting.

And finally, it was found that the calorie-restricted group had remarkably low triglyceride levels. In fact, they were as low as lowest 5 percent of americans in their 20s. This is more remarkable when it is noted that the calorie-restricted individuals were actually aged between 35 and 82 years.

How did calorie-restriction affect blood pressure levels?

Both systolic and diastolic blood pressure levels in calorie-restricted group were remarkably low, about 100/60, values normally found in 10-year-old children. In contrast, the average blood pressure for the normal diet group was about 130/80 (which is standard for the typical american).

For the 12 individuals who had medical data concerning their blood pressure before they started calorie restriction, it was found that their starting blood pressures were similar to those of the comparison group. Their large decreases in systolic and diastolic blood pressures occurred during the first year of following a calorie-restricted diet with a further decrease to extremely low levels in the period after that.

How did calorie-restriction affect insulin and glucose levels?

Fasting plasma insulin concentration was 65% lower and fasting plasma glucose concentration was also significantly lower in the calorie-restricted group when compared with the comparison group.

What do all these findings mean?

This means that the results show that calorie restrictions results in large, sustained, beneficial changes to a person’s risk factors for atherosclerosis: total cholesterol, LDL cholesterol, HDL cholesterol, triglyceride levels and blood pressure.

Calorie-restriction also provides a powerful protective effect against obesity and insulin resistance (a risk factor for developing type 2 diabetes).

Could the findings be due to vitamin supplements the people were taking?

It appears that taking vitamin supplements made little difference to the results of the study.

Many of the calorie-restricted individuals and comparison subjects took a wide range of supplements. While four calorie-restricted dieters and three comparison subjects did not take any supplements at all. The researchers found that serum lipid, lipoprotein and blood pressure levels of those not taking supplements showed no statistically significant difference from those who were taking supplements.

Can the results of the study be trusted?

While the results of the study appear to be compelling, it must be remembered that the results are based on a very small sample of people – only 18 people who followed the calorie-restricted diet. This means that it is difficult to be certain that these findings are definitely the result of calorie restriction and not some other factor. Much larger trials will be needed to confirm these findings and the study’s researchers are running a larger controlled, prospective study to do this.

Also, the current study only followed people on a calorie-restricted diet for an average of six years. This means that the long-term effects of calorie restriction are unknown and its long-term safety is still unclear. For this reason, the researchers will be running their new study for a longer period.

Is a calorie-restricted diet recommended?

Because there is still uncertainty surrounding the effects and safety of a calorie-restricted diet, the medical community is cautious about recommending this approach as a way of reducing heart disease and diabetes risk. However, the results of this study have been welcomed by UK doctors as further support of the health benefits of eating a healthy, balanced diet and maintaining a healthy weight by being physically active.

What can we do to reduce our risk of heart disease, stroke and type 2 diabetes?

The current advice is:

  • keep at a healthy weight or lose excess weight if necessary (you should aim for a BMI of 25 or less)
  • reduce the amount of salt you eat (to less than 6g a day)
  • eat five portions of fruit and vegetables a day
  • give up smoking
  • learn to relax and reduce stress
  • cut down on alcohol (Men should aim to drink no more than 3-4 units of alcohol per day with a maximum of 21 units a week. Women should aim for no more than 2-3 units per day with a maximum of 14 units a week.)
  • aim to be physically active for about 30 minutes on five or more days of the week