The study was carried out by researchers from University of Otago Medical School, New Zealand. Funding was provided by Genesis Oncology Trust, the Dean’s Bequest Funds of the Dunedin School of Medicine, the Gisborne East Coast Cancer Research Trust and the Director’s Cancer Research Trust. The research was published in the peer-reviewed American Journal of Epidemiology. This was a case-control study in New Zealand that compared a group of adults with bowel cancer, and a group without bowel cancer, and looked at whether they drank milk at school. School milk was freely available in most schools in New Zealand until 1967 when the government programme was stopped. Many schools in the Southland region stopped free milk as long ago as 1950.
Case-control studies are appropriate for looking at whether people with and without a disease have had a particular exposure (milk in this case). The difficulty is in accounting for all potential confounding factors, particularly other health and lifestyle factors, which could be related to both diet and bowel cancer risk, for example regular childhood milk consumption could be a reflection of a ‘healthy’ diet and other healthy lifestyle behaviours that may reduce risk of cancer. In addition, when examining such a specific dietary factor – ie milk consumed in school – it is difficult to account for all possible milk or other dairy products consumed outside of school.
In this case-control study, 562 adults (aged 30 to 69) with newly diagnosed bowel cancer were identified from the New Zealand Cancer Registry in 2007. For a control group, 571 age-matched adults without cancer were randomly selected from the electoral register. All participants were mailed a questionnaire that asked about any previous illness, use of aspirin or dietary supplements in childhood, participation in school milk programmes, other childhood milk consumption, childhood diet (including other milk and dairy), smoking, alcohol consumption prior to 25 years of age, screening tests for bowel cancer, family history of cancer, education and sociodemographic characteristics. Childhood weight and height were not questioned. For school milk consumption they were specifically asked:
- Whether they drank school milk
- How many half-pint bottles they drank a week
- What age they first drank school milk
- When they stopped drinking school milk
Statistical risk associations between school milk participation and cancer were calculated. The calculations took into account several risk factors for bowel cancer risk including age, sex, ethnicity and family history.
What were the basic results?
Data on school milk consumption was available for 552 cases and 569 controls. As expected, people who started school before 1967 were more likely to have had free school milk than those who began school after 1968. Seventy-eight percent of cases participated in the school milk programme compared with 82% of controls. School milk consumption was associated with a 30% reduced risk of developing bowel cancer (odds ratio 0.70, 95% confidence interval 0.51 to 0.96).
When looking at the effect of number of bottles consumed per week they found that compared with no bottles, five bottles per week was associated with 32% significantly decreased risk, and 10 or more bottles with 61% significantly decreased risk. However, there was no significant association with one to four bottles or six to nine bottles. The researchers found a similar trend when the total school consumption of milk was compared with no consumption: 1,200-1,599 bottles was associated with 38% significantly decreased risk; 1,600-1,799 with 43% decreased risk; and 1,800 or more bottles associated with 38% significantly decreased risk. There was no significant association with fewer than 1,200 bottles. The researchers calculated that for every 100 half-pint bottles consumed at school there was a 2.1% reduction in the risk of bowel cancer. Outside of school, there was a significantly reduced risk of bowel cancer with more than 20 dairy products a week compared with none to nine dairy products a week.
The researchers conclude that their national case-control study ‘provides evidence that school milk consumption was associated with a reduction in the risk of adult colorectal cancer in New Zealand. Furthermore, a dose-dependent relation was evident’. This study has strengths in its relatively large size, its reliable and nationally representative identification of cases and controls, and its thorough data collection. However, the conclusion that school milk consumption is associated with a reduced risk of bowel cancer in adulthood must be interpreted in light of a number of considerations:
The analysis took into account established risk factors for bowel cancer including age, sex, ethnicity and family history. However, many other potential confounders were not considered, including diet, physical activity, overweight and obesity, smoking or alcohol consumption. Diet in particular has been implicated in bowel cancer risk, with diets high in saturated fat, red meat and processed foods and low in fibre, fruit and vegetables thought to increase risk. Potentially, any of these lifestyle behaviours could be confounding the relationship between school milk consumption and bowel cancer and regular childhood milk consumption could be a reflection of a ‘healthy’ diet and other healthy lifestyle behaviours that reduce risk of cancer. When looking at the effect of number of bottles consumed per week, the researchers found that, compared with no bottles, five bottles were associated with 32% significantly decreased risk and 10 or more bottles with 61% significantly decreased risk. However, there was no significant association with one to four bottles or six to nine bottles. Therefore, the trend here is not very clear. Particularly as only 16 cases and 31 controls drank 10 or more bottles a week, statistical comparison between such small numbers should be viewed with caution. With many food questionnaires there is the potential for recall bias. For example, adults may have difficulty remembering how many bottles of school milk they drank many years before. When estimating their average weekly amount, it is highly possible that this could be inaccurate or that their consumption varied slightly from week to week and year to year. Particularly when researchers were using this response and combining it with the number of weeks in the school year and their total years at school to give a total number of bottles consumed at school (figures in 100s or 1,000s), there is the possibility of being incorrectly categorised. Hence, there may be less reliability when calculating risk according to the category of total milk bottles consumed. Cancer prevalence, and particularly environmental and lifestyle risk factors for cancer, can vary between countries. These findings in New Zealand may not be represented elsewhere. Of note, the researchers acknowledge that a cohort study in the UK found the opposite: increased childhood dairy consumption was associated with increased risk of bowel cancer. Case-control studies are most appropriate for looking at rare diseases, where you would expect there to be only a small number of cases developing among a large number of people. In the case of bowel cancer, which is common, the slightly more reliable cohort design could have also been used, where children who drank milk at school and those who didn’t were followed over time to see if they developed cancer. However, such a cohort would consequently need extensive long-term follow-up.
The possible association between milk/dairy consumption, or calcium intake, in childhood, or in later years, is worthy of further study. However, from this study alone, it cannot be concluded that school milk prevents bowel cancer later in life.
Primary school children who don't like eating fruit and vegetables are 13 times more likely to develop functional constipation than children who do, according to a study in the December issue of the Journal of Clinical Nursing. Drinking less than 400ml of fluid a day also significantly increases the risk. Dr Moon Fai Chan, assistant professor at the National University of Singapore, teamed up with Yuk Ling Chan, from the Hong Kong Polytechnic University, to study the diet and toileting habits of 383 children aged from eight to ten from a school in Hong Kong. Fifty-one per cent were boys and children who were on regular medication or who paid regular hospital or clinic visits were excluded. Seventy per cent of the children who took part in the study were ten-years-old, 22 per cent were nine and eight per cent were eight.
“A number of studies have suggested that functional constipation – which is due to dietary habits, environmental habits and psychosocial factors rather than a particular health problem – is getting worse among school-age children” says Dr Moon Fai Chan from the Alice Lee Centre for Nursing Study at the University. “It is estimated that functional constipation accounts for 95 per cent of cases of constipation affecting children once they pass infancy. The condition has serious consequences, as it can cause a wide range of distressing emotional and physical problems such as stress, soiling, problems at school, damaged self-confidence and reduced social interaction.”
Key findings of the study included:
- Seven per cent of the children who took part suffered from functional constipation and there were clear dietary differences between the children who did and did not have problems.
- Girls were more likely to have functional constipation than boys (8.2 per cent versus 6.6 per cent) and nine-year-olds were more likely to report problems (13.3 per cent) than eight-year-olds (10 per cent) and ten-year-olds (5.2 per cent).
- Children who only drank 200ml to 400ml of fluid a day were eight times more likely to experience problems than children who drank 600ml to 800ml and 14 times more likely than children who drank a litre or more.
- Children who said they did not like fruit or vegetables were 13 times more likely to suffer from functional constipation than children who did.
- Nine out of ten children refused to use the school toilets for bowel movements and the figure was the same for children with and without constipation.
The biggest problems with school toilets were that children preferred to go at home. They also cited lack of toilet paper and dirty toilets. “When we compared our findings with previous studies we found that the levels of functional constipation among Hong Kong school children was higher than those in the USA and UK, but similar to Italy” says Dr Chan. The authors have made a number of recommendations that they feel would help to tackle the problem. They suggest that:
- Primary schools should work with healthcare professionals to make children more aware of the problem, with regular healthcare education sessions in classrooms and at assemblies.
- Parents need to be educated about functional constipation so that they can spot problems in their children and make sure that their diet provides sufficient fluid, vegetables and fruit. They should also remind their children to pay regular toilet visits at school.
- School tuck-shops should stock high-fibre snacks such as popcorn, fresh food and dried fruit, instead of crisps and sweets.
- Children should be encouraged to drink plain water during lessons and drinking fountains should be installed.
- School toilets should be more user-friendly, private and well stocked with paper so that children feel more comfortable using them.
“We hope that this study will help to raise awareness of functional constipation, which can cause children real physical and emotional distress and seriously affect their quality of life” says Dr Chan.
Source: Investigating factors associated with functional constipation of primary school children in Hong Kong. Chan MF and Chan YL. Journal of Clinical Nursing. 19, pp3390-3400. (December 2010). DOI: 10.1111/j.1365-2702.2010.03366.x
A new study finds that drinking orange juice, soda and other beverages high in the sugar fructose could increase the small risk that middle-age and elderly women have of developing gout. Gout is a painful form of arthritis caused by too much uric acid in the blood. For women in the study who drank two or more servings of these beverages per day, the risk of gout was more than double that for women who drank sugary sodas and juices less than once per month. Because gout is relatively rare among women, the drinks probably contribute only moderately to a woman's chances of developing it. Still, this is the first study linking sodas and sweetened fruit juices to women's gout risk. Previous research found such a link for men.
The study will be published in the Nov. 24 issue of the Journal of the American Medical Association, and is being presented today (Nov. 10) at the American College of Rheumatology annual scientific meeting.
Gout occurs when levels of uric acid in the blood become too high, and uric acid crystallizes around the joints, leading to inflammation, swelling and pain. Foods than can increase the levels of uric acid in the blood include organ meats (such as kidneys and livers), asparagus and mushrooms, according to the Mayo Clinic. Fructose is also known to increase blood uric acid levels, the researchers said. While gout is not common in the United States, the rate of incidences has more than doubled over a 20-year period, from 16 cases per 100,000 Americans in 1977 to 42 per 100,000 in 1996. Over this period, the researchers noted, the population also consumed increasing amounts of soda and other drinks sweetened with fructose.
The new study followed 78,906 women for 22 years, from 1984 to 2006, as part of the Nurses' Health Study. At the beginning of the study, none of the women had gout. By the end, 778 had developed it. Women who drank one serving of soda per day were 1.74 times more likely to develop gout than those who drank less than one serving per month. Those who drank two or more servings per day were 2.4 times more likely to develop gout. Drinking two or more servings of soda per day caused an additional 68 cases of gout per 100,000 women per year, compared with drinking less than one serving of soda per month, the researchers said. Drinking orange juice also increased the risk. Women who drank one serving of orange juice per day were 1.41 times more likely to develop gout, and those who drank two or more servings were 2.4 times more likely to report gout.
Lifestyle and diet
The rise in gout cases is most likely due to changes in lifestyle and diet and an increase in conditions associated with gout, such as metabolic syndrome, said study researcher Dr. Hyon K. Choi of the Boston University School of Medicine. The results held even after the researchers took into account factors that could have influenced the findings, such as age, body mass index and whether the women had gone through menopause, Choi said.
The findings suggest diets to prevent gout should reduce fructose intake, the researchers said.
The study was funded by the National Institutes of Health.
Could drinking one or more artificially sweetened, carbonated diet sodas a day boost a woman's odds of premature delivery? A new study from Denmark suggests such a link.dblclick('xxlA');
The researchers looked at the soft drink habits of nearly 60,000 Danish women enrolled in a national study there from 1996 to 2002. The investigators found a link between the intake of diet carbonated drinks and, to a lesser extent, diet noncarbonated drinks and delivering a baby early.
The study is published online and in the September print issue of the American Journal of Clinical Nutrition. In the report, the researchers conclude: “Daily intake of artificially sweetened soft drinks may increase the risk of preterm delivery.”
The researchers defined preterm as delivering before 37 weeks' gestation. They categorized the women into groups depending on beverage drinking habits: those who never drank soft drinks or those who drank less than one per week, one to six per week, one each day, two or three per day, or four or more daily. In all, 4.6 percent of the women delivered early, and one-third of those deliveries were medically induced. The team found no association between the premature delivery and the intake of carbonated drinks sweetened with sugar.
However, compared with those who never drank the beverages, women who downed four or more diet (artificially sweetened) carbonated drinks a day were 78 percent more likely to deliver early than women who never drank the beverages. And those who had four or more diet, noncarbonated drinks daily were 29 percent more likely to deliver early. Those who had one or more carbonated diet drinks a day were 38 percent more likely to deliver early.
Why the diet drinks, especially, were linked with early delivery is not known, but the researchers speculate that the link may be driven by high blood pressure disorders in pregnancy. They note that other studies have found a link between soft drinks and high blood pressure in non-pregnant women.
Where did the story come from?
The study was carried out by researchers from Hopital de la Pitie and the IPC (Investigations Preventives et Cliniques) Center in Paris, France. It was funded by French public health bodies, the Caisse Nationale d'Assurance Maladie (CNAM) and the Caisse Primaire d'Assurance Maladie de Paris (CPAM-Paris). The study was published in the peer-reviewed European Journal of Clinical Nutrition.
This research was generally covered well by the media, with most stories making it clear that alcohol had not been found to improve health, but rather that people who drank moderately also had better health and social status. The messages from some headlines were more misleading, however, with Metro claiming that “Drinking wine makes you happier” and The Sun suggesting that booze “aids the body”.
The Daily Mail featured particularly clear coverage, with both its headline and article clearly explaining that the good health of moderate drinkers is more likely to be down to healthier diet, exercise and work–life balance rather than any supposed benefits of alcohol.
What kind of research was this?
This cross-sectional study analysed the relationship between alcohol intake, other cardiovascular risk factors and health status in a large French population. The aim was to evaluate potential confounding factors that may be behind the supposed cardiovascular benefits of alcohol.The researchers looked at data on the clinical and biological characteristics of nearly 150,000 people, which were gathered as part of a large ongoing cohort study.
Several observational studies have shown an association between moderate alcohol intake and a lower risk of cardiovascular disease. The lower risk is often attributed to alcohol having beneficial effects on blood levels of lipids, such as cholesterol, or on other factors, such as the effect of the antioxidants in alcoholic drinks. The researchers point out that addressing the underlying message implied by previous data, that moderate alcohol intake is good for health, is particularly important in France, which has one of the highest average individual alcohol intakes in the world.
The researchers also stress that the findings from observational studies need to be viewed with caution, so they assessed a number of key factors not taken into account by previous research. These key, but generally unexplored, factors included mental wellbeing, subjective health status and social factors.
What did the research involve?
All the people in the study underwent a clinical examination between 1999 and 2005, which included measurements blood pressure, waist circumference, cholesterol, respiratory function and heart rate. Also recorded were tobacco use, physical activity, personal medical history, current medications, social status and occupation. Stress and depression scores were assessed using validated questionnaires, and people were also asked to estimate their own health status.
Alcohol intake was quantified as the number of standardised glasses of pure alcohol (10g a glass) consumed each day, and different types of alcoholic drink were also recorded. People were divided into four groups according to their alcohol consumption: never, low (less than 1 glass a day), moderate (1-3 glasses a day) or high (more than 3 glasses a day). Former drinkers were analysed as a separate group. Established statistical techniques were used to analyse the relationship between alcohol intake and all the other factors. The results were adjusted to account for the influence of age and were also broken down by gender.
What were the basic results?
The researchers found that:
13.7% of men and 23.9% of women did not drink at all. Total alcohol intake increased with age in both sexes. Apart from people aged under 30, most people drank wine. They found that women who drank moderate amounts of alcohol had lower body mass index, waist circumference, blood pressure and blood lipids, including LDL (“bad”) cholesterol. Men who drank moderately had lower body mass index, heart rate, blood pressure, some blood lipids (triglycerides) and fasting glucose levels, plus lower stress and depression scores.
Men who drank little or moderately were also more likely to have better self-assessed health status, social status and respiratory function. In both sexes, alcohol intake was strongly associated with higher levels of HDL (“good”) cholesterol, a finding which was independent of the type of alcoholic beverage consumed.
How did the researchers interpret the results?
The researchers concluded that moderate and low consumption of alcohol was strongly associated with several clinical, social and biological characteristics that point to overall better health status and a lower risk of cardiovascular disease. Importantly, they say, few of these factors seem causally related to alcohol consumption.
They point out that social status was “strikingly different” across the groups, with moderate alcohol consumption being a “powerful general indicator” of social status. Risk factors that have never been taken into account before, such as social and professional status, anxiety score and heart rate, were all more favourable in moderate consumers.
Their results, they say, raise the possibility that the seemingly protective effects of moderate alcohol consumption found in previous research may have been due to the researchers not fully taking account of possible confounders.
This research adds a note of caution to the results of previous studies. It concludes that moderate alcohol consumption may be a marker of better health and lower cardiovascular risk rather than a cause of these improvements.
The study's strength is that it is based on a relatively large cohort and that standardised, validated methods were used to collect clinical and biological information. The main weakness of the study is its cross-sectional design, which means that people were not followed up over time to see if they developed disease. This also meant that deaths from heart disease, for example, were not reported.
Another limitation is that alcohol intake was based on self–reported data. This leaves a possibility for error as accurate recall of alcohol consumption is notoriously hard in this type of study. Future research in this area will ideally follow people over time and carefully measure possible risk factors to establish whether alcohol has any direct, causal role in protection from heart disease.
Overall, this study has implications for public health. As the researchers say, its results suggest that it is premature to promote alcohol consumption as an independent factor for cardiovascular protection, as some have proposed based on past research.