ironjustice
2010-06-13 23:54:22 UTC
Diet and asthma link researched
Published Date: 04 June 2010
"Three burgers a week could be enough to bring on asthma," The Daily
Express claimed. Several other newspapers have also reported the
results of an international study that looked at asthma risk and
eating habits of over 50,000 children in 20 countries.
The study behind these news reports is flawed due to several problems
noted by the researchers. For example, they did not measure important
risk factors, such as the children’s weight, or fully account for
their social and economic background. Some interesting trends in the
results were mentioned by the Express, for example that a diet high in
fish is linked to less asthma symptoms in rich countries, while
youngsters in poor countries had fewer symptoms if they ate a diet
rich in cooked vegetables.
This study will need to be followed by others that look at, and adjust
for, all known risk factors and follow participants over time. This is
necessary to establish whether diet directly affects asthma risk, or
whether diet is an indicator of social factors that influence the
condition.
Where did the story come from?The study was carried out by researchers
from Germany, Spain and London, along with a large supporting study
group that supplied its data. The co-ordination and analysis were
funded by the Fifth Framework Programme of the European Commission,
whereas the field work and data collection were funded locally.
The study was published in Thorax, a peer-reviewed medical journal.
The other papers and news sources reporting on this study discussed
its limitations in varying amounts of detail. For example. the BBC
picked up on the fact that the link to burgers was only shown in
wealthy countries, while The Daily Telegraph commented on a
theoretical biological basis for the findings. The Telegraph pointed
out that foods such as fruit and vegetables are rich in vitamin C or
antioxidants, which may explain the link between diet and asthma. Most
of the stories implied that the study is yet another reason to follow
a healthy diet.
What kind of research was this?The aim of this research was to
investigate how different foods, particularly the “Mediterranean-type
diet”, are linked to asthma symptoms and diagnosis and allergies in
children. The authors point out that previous reports in this area had
not used objective measurements of allergy (also known as atopy), such
as skin prick testing, so they hoped to use an improved study design
to investigate the association between diet and increasing rates of
asthma and atopy in Western countries.
The study was large and the researchers catalogued an impressive list
of food types, scoring them on how closely they match the idealised
Mediterranean dietary pattern. The objective measurement of atopy,
through skin prick testing, was a strength of the study, although no
food items were subsequently found to be linked to allergic
sensitisation. As the study did not include measurements of the
participants’ weight or energy intake, it is not possible to gauge the
extent to which any link could be related to being overweight or
obese, which are thought to be associated with asthma.
What did the research involve?The International Study on Allergies and
Asthma in Childhood (ISAAC) study is a long-running study in 29
centres in 20 countries around the world. Overall, it reports
important differences in the rates of asthma between countries and
aims to improve the understanding of the possible causes of these
differences.
This piece of research was a sub-study using data from the ISAAC
study. To gather their population, the researchers picked a random
sample of at least 10 schools in a defined geographical area of each
country and chose more than 1,000 children from each of these centres.
Overall, about 63,000 (76.4% of those eligible) schoolchildren between
8 and 12 years old were invited to take part. Between 1995 and 2005,
parents provided 50,004 complete questionnaires on their children’s
diet
These food questionnaires asked about allergic symptoms and diseases.
The researchers also tested 29,579 (59%) of them with skin prick
testing to see if they had allergic sensitivities to the common
allergens. They then used standard statistical techniques to test the
strength of any links found in a cross-sectional analysis. They
adjusted the analysis in several ways for age, sex, environmental
tobacco smoke, parental atopy(allergy), exercise, number of siblings
and maternal education.
The parental questionnaires asked for information on those foods
already thought to be linked to asthma or allergies. This was based on
theories of the contributory or preventative role of antioxidants and
oily fish or saturated fat intake in these conditions. The
questionnaire asked about meat, fish, fresh fruit, raw green
vegetables, cooked green vegetables, burgers, fruit juice and fizzy
drink. They scored food intake according to how well it matched the
Mediterranean dietary pattern, characterised by high fruit and
vegetable intake and low consumption of saturated fatty acids from
animal sources.
The researchers also collected data on age, sex and some of the other
factors thought to be linked to asthma, such as current exposure to
environmental tobacco smoke, number of brothers or sisters, parents’
history of asthma, hay fever or eczema and exercise. Most centres
invited all children in that region for skin prick testing, where the
researchers tested for six common airborne allergens, including house
dust mites, cat hair, and tree and grass pollen. Importantly, the
children were not weighed at this visit.
So that they could test any differences between the countries, the
researchers also classified the study centres into two broad
categories based on gross national income (GNI) per capita. They
defined “non-affluent” countries as those where GNI was less than
$9,200 a year per capita.
What were the basic results?After the researchers’ statistical
adjustments, fruit intake was associated with a lower rate of symptoms
of wheezing in both affluent and non-affluent countries. Consumption
of fish in affluent countries and cooked green vegetables in non-
affluent countries were associated with a lower rate of symptoms of
wheezing.
In all countries, more frequent consumption of fish and cooked or raw
vegetables was associated with a lower reported rates of asthma
diagnosis. Burger consumption was associated with higher lifetime
rates of asthma diagnosis.
Further analysis across all countries showed that, compared with no or
occasional consumption, the consumption of burgers more than three
times a week was associated with about a 40% increased risk of asthma
diagnosis (adjusted odds ratio 1.42, 95% confidence interval 1.08 to
1.87).
On the skin prick testing, none of the food items was associated with
allergic sensitisation.
Food considered to be part of the Mediterranean diet was associated
with a lower prevalence of current wheeze and asthma.
How did the researchers interpret the results?The researchers say that
diet is associated with wheeze and asthma but not with allergic
sensitisation in children. They claim that their results provide
further evidence that eating a Mediterranean diet may provide some
protection against wheeze and asthma in childhood.
ConclusionThis large, carefully conducted study set out to provide new
international data regarding the different rates of asthma and
allergies between countries. The researchers tested theories of how
food might be linked to the causes of these conditions. Several
limitations are mentioned by the authors:
The dietary questionnaire asked about past eating habits in children.
These may have not been accurately remembered or reported by parents.
This may have reduced or increased the strength of the associations
reported. The researchers selected the foods that are part of either
Western or Mediterranean dietary patterns and, as mentioned by several
newspapers, were unable to adjust for total energy intake and body
mass index, which were not asked about or measured. This is an
important limitation as asthma is thought to be linked to being
overweight. The researchers performed numerous statistical
comparisons, which increases the likelihood of finding a significant
result simply due to chance. Overall, this study has improved the
understanding of how asthma rates may differ across the world, but has
raised further questions about the link between diet and asthma.
Ideally, the potential link will be explored through studies that
control for all the other factors thought to increase the risk of
asthma.
There are many good reasons to eat healthily. We do not yet know
whether avoiding asthma is one of them, but it’s best to follow a
balanced diet regardless.
reserved.
Who loves ya.
Tom
Jesus Was A Vegetarian!
http://tinyurl.com/2r2nkh
Man Is A Herbivore!
http://tinyurl.com/a3cc3
DEAD PEOPLE WALKING
http://tinyurl.com/zk9fk
Published Date: 04 June 2010
"Three burgers a week could be enough to bring on asthma," The Daily
Express claimed. Several other newspapers have also reported the
results of an international study that looked at asthma risk and
eating habits of over 50,000 children in 20 countries.
The study behind these news reports is flawed due to several problems
noted by the researchers. For example, they did not measure important
risk factors, such as the children’s weight, or fully account for
their social and economic background. Some interesting trends in the
results were mentioned by the Express, for example that a diet high in
fish is linked to less asthma symptoms in rich countries, while
youngsters in poor countries had fewer symptoms if they ate a diet
rich in cooked vegetables.
This study will need to be followed by others that look at, and adjust
for, all known risk factors and follow participants over time. This is
necessary to establish whether diet directly affects asthma risk, or
whether diet is an indicator of social factors that influence the
condition.
Where did the story come from?The study was carried out by researchers
from Germany, Spain and London, along with a large supporting study
group that supplied its data. The co-ordination and analysis were
funded by the Fifth Framework Programme of the European Commission,
whereas the field work and data collection were funded locally.
The study was published in Thorax, a peer-reviewed medical journal.
The other papers and news sources reporting on this study discussed
its limitations in varying amounts of detail. For example. the BBC
picked up on the fact that the link to burgers was only shown in
wealthy countries, while The Daily Telegraph commented on a
theoretical biological basis for the findings. The Telegraph pointed
out that foods such as fruit and vegetables are rich in vitamin C or
antioxidants, which may explain the link between diet and asthma. Most
of the stories implied that the study is yet another reason to follow
a healthy diet.
What kind of research was this?The aim of this research was to
investigate how different foods, particularly the “Mediterranean-type
diet”, are linked to asthma symptoms and diagnosis and allergies in
children. The authors point out that previous reports in this area had
not used objective measurements of allergy (also known as atopy), such
as skin prick testing, so they hoped to use an improved study design
to investigate the association between diet and increasing rates of
asthma and atopy in Western countries.
The study was large and the researchers catalogued an impressive list
of food types, scoring them on how closely they match the idealised
Mediterranean dietary pattern. The objective measurement of atopy,
through skin prick testing, was a strength of the study, although no
food items were subsequently found to be linked to allergic
sensitisation. As the study did not include measurements of the
participants’ weight or energy intake, it is not possible to gauge the
extent to which any link could be related to being overweight or
obese, which are thought to be associated with asthma.
What did the research involve?The International Study on Allergies and
Asthma in Childhood (ISAAC) study is a long-running study in 29
centres in 20 countries around the world. Overall, it reports
important differences in the rates of asthma between countries and
aims to improve the understanding of the possible causes of these
differences.
This piece of research was a sub-study using data from the ISAAC
study. To gather their population, the researchers picked a random
sample of at least 10 schools in a defined geographical area of each
country and chose more than 1,000 children from each of these centres.
Overall, about 63,000 (76.4% of those eligible) schoolchildren between
8 and 12 years old were invited to take part. Between 1995 and 2005,
parents provided 50,004 complete questionnaires on their children’s
diet
These food questionnaires asked about allergic symptoms and diseases.
The researchers also tested 29,579 (59%) of them with skin prick
testing to see if they had allergic sensitivities to the common
allergens. They then used standard statistical techniques to test the
strength of any links found in a cross-sectional analysis. They
adjusted the analysis in several ways for age, sex, environmental
tobacco smoke, parental atopy(allergy), exercise, number of siblings
and maternal education.
The parental questionnaires asked for information on those foods
already thought to be linked to asthma or allergies. This was based on
theories of the contributory or preventative role of antioxidants and
oily fish or saturated fat intake in these conditions. The
questionnaire asked about meat, fish, fresh fruit, raw green
vegetables, cooked green vegetables, burgers, fruit juice and fizzy
drink. They scored food intake according to how well it matched the
Mediterranean dietary pattern, characterised by high fruit and
vegetable intake and low consumption of saturated fatty acids from
animal sources.
The researchers also collected data on age, sex and some of the other
factors thought to be linked to asthma, such as current exposure to
environmental tobacco smoke, number of brothers or sisters, parents’
history of asthma, hay fever or eczema and exercise. Most centres
invited all children in that region for skin prick testing, where the
researchers tested for six common airborne allergens, including house
dust mites, cat hair, and tree and grass pollen. Importantly, the
children were not weighed at this visit.
So that they could test any differences between the countries, the
researchers also classified the study centres into two broad
categories based on gross national income (GNI) per capita. They
defined “non-affluent” countries as those where GNI was less than
$9,200 a year per capita.
What were the basic results?After the researchers’ statistical
adjustments, fruit intake was associated with a lower rate of symptoms
of wheezing in both affluent and non-affluent countries. Consumption
of fish in affluent countries and cooked green vegetables in non-
affluent countries were associated with a lower rate of symptoms of
wheezing.
In all countries, more frequent consumption of fish and cooked or raw
vegetables was associated with a lower reported rates of asthma
diagnosis. Burger consumption was associated with higher lifetime
rates of asthma diagnosis.
Further analysis across all countries showed that, compared with no or
occasional consumption, the consumption of burgers more than three
times a week was associated with about a 40% increased risk of asthma
diagnosis (adjusted odds ratio 1.42, 95% confidence interval 1.08 to
1.87).
On the skin prick testing, none of the food items was associated with
allergic sensitisation.
Food considered to be part of the Mediterranean diet was associated
with a lower prevalence of current wheeze and asthma.
How did the researchers interpret the results?The researchers say that
diet is associated with wheeze and asthma but not with allergic
sensitisation in children. They claim that their results provide
further evidence that eating a Mediterranean diet may provide some
protection against wheeze and asthma in childhood.
ConclusionThis large, carefully conducted study set out to provide new
international data regarding the different rates of asthma and
allergies between countries. The researchers tested theories of how
food might be linked to the causes of these conditions. Several
limitations are mentioned by the authors:
The dietary questionnaire asked about past eating habits in children.
These may have not been accurately remembered or reported by parents.
This may have reduced or increased the strength of the associations
reported. The researchers selected the foods that are part of either
Western or Mediterranean dietary patterns and, as mentioned by several
newspapers, were unable to adjust for total energy intake and body
mass index, which were not asked about or measured. This is an
important limitation as asthma is thought to be linked to being
overweight. The researchers performed numerous statistical
comparisons, which increases the likelihood of finding a significant
result simply due to chance. Overall, this study has improved the
understanding of how asthma rates may differ across the world, but has
raised further questions about the link between diet and asthma.
Ideally, the potential link will be explored through studies that
control for all the other factors thought to increase the risk of
asthma.
There are many good reasons to eat healthily. We do not yet know
whether avoiding asthma is one of them, but it’s best to follow a
balanced diet regardless.
reserved.
Who loves ya.
Tom
Jesus Was A Vegetarian!
http://tinyurl.com/2r2nkh
Man Is A Herbivore!
http://tinyurl.com/a3cc3
DEAD PEOPLE WALKING
http://tinyurl.com/zk9fk