Prevention of Obesity and Type 2 Diabetes in New Zealand Children.
A report published by
DiabetesNew Zealand Inc and Fight the Obesity Epidemic Inc.
Limitations of this review
The scope of this review was limited to just several major areas of interventions relating to nutrition and physical activity promotion. This review was prepared as background for submissions on the proposed Public Health Legislation and as such only a fraction of the thousands of potentially relevant Medline-indexed articles relating to nutrition and physical activity interventions were examined. Furthermore, this report did not include a comprehensive examination of New Zealand-specific grey literature (eg, unpublished reports).
This review has put a lot of weight on the evidence from systematic reviews of randomised controlled trials, particularly for the physical activity interventions examined by the Task Force on Community Prevention Services (TFCPS). Some experts in evaluation methodology have suggested the need for more comprehensive and complex criteria to be used in evaluating evidence for public health interventions1 relative to that used by such Task Forces. Rychetnik et al suggest that the appraisal of public health interventions should encompass not only the credibility of the evidence, “but also its completeness and transferability”. Furthermore, the evaluation of an intervention’s effectiveness should be “matched with the stage of the development of that intervention”; be designed to “detect all the important effects of the intervention”; and encapsulate “the interests of all the important stakeholders”. However, these issues are not well developed in most of the reviews covered in this document.
Finally, this report has not yet been peer reviewed by experts in the relevant specific areas of nutrition promotion, physical activity promotion, obesity prevention and diabetes prevention.
Aims The aim of this report is twofold: to describe the magnitude of the obesity epidemic as it relates to New Zealand and to consider the likely drivers of this. Secondly, to briefly review the evidence relating to legislation and regulations that play a role in the prevention of obesity and diabetes – through primarily nutritional and physical activity interventions.
Method Searches were carried out during 2002 of Medline, the Cochrane Collaboration Library, and the findings of major Task Forces for relevant articles (particularly systematic reviews).
Findings 1) Obesity and type two diabetes are increasing at an alarming rate in all developed countries including New Zealand. Latest figures from the Ministry of Health (Rigby, Commonwealth Health Ministers Meeting, Christchurch, Nov 2001) demonstrate that there has been a 50% increase in obesity in New Zealand since 1989. The Ministry of Health’s models and forecasts for diabetes in New Zealand released in 2002 describe an epidemic of type 2 diabetes with the prevalence of known diabetes increasing from 81,000 in 1996 to 145,000 in 2011. This represents an increase in prevalence over the 15-year period of 20% for Europeans, 34% for Pacific islanders and a 38% increase for Maori. These numbers probably describe half the burden of disease, as we know that for every person with diabetes there is one other undiagnosed. Pacific and Maori people living with diabetes lose on average about 12 years of life expectancy and Europeans about seven years. In total, almost 2,000 years of life were lost to diabetes in 1996.
2) There is evidence for interventions to prevent obesity and diabetes by improving nutrition
Regulations on food advertising and television: There is good evidence that the content of televised food advertising in developed countries (including New Zealand) is that of a dietary pattern (high in fat and sugar) that poses risks of obesity. Furthermore, experimental evidence indicates that food advertising directly impacts on the eating behaviour of children. Other randomised trials indicate that children’s television viewing time can be reduced, and in one trial it decreased body mass. Some countries ban television advertising directed at children, and in one of these, Poland, the ban was associated with reduced soft drink sales. Studies on alcohol and tobacco advertising also strongly suggest that advertising bans and restrictions work. There is a range of plausible regulations to restrict food advertising that could be used in the New Zealand setting.
Regulations to facilitate the use of economic instruments: There is good evidence that price is an important determinant of food purchasing. Although the evidence with regard to food is limited, there is strong evidence for alcohol and for tobacco. There is a range of plausible regulatory interventions that include removing GST from vegetables and fruit and introducing specific taxes on saturated fats, free sugars and even ruminant livestock.
Regulations to improve food labelling: There is good evidence that consumers in developed countries, including New Zealand, read food labels. Other evidence links such knowledge obtained from labels to actual dietary changes. There is also a strong body of evidence that labels on alcoholic beverages and tobacco products can lead to changes in knowledge and behaviour. Although the overall impact of food labels may be relatively modest, this impact could be enhanced given the evidence on the importance of good label design. There is also a consumers’ rights argument for having informative food labelling. In New Zealand there is a range of plausible regulations that could further advance food labelling eg, expanding the heart tick or introducing a symbol to signal nutritious foods with a low glycaemic load.
Other possible regulations to reduce excessive food intake and improve nutrition: There are many other plausible regulatory interventions that were not reviewed in detail in this report. These include the development of a “Health Information Authority”; controls on the use of fat in takeaway outlets; minimum standards for televised cooking programmes; minimum standards for restaurant meals and standards for portion sizes.
Possible regulatory interventions focused on the school setting and children include: minimal levels of nutrition education at schools and restrictions on the following: food industry sponsorship; food sales at and near schools; and vending machines.
3) There is evidence for interventions to prevent obesity and diabetes by promoting physical activity Creation of or enhanced access to, places for physical activity combined with informational outreach activities: A systematic review has found strong evidence from well-designed studies that these interventions increase physical activity levels. There is a range of plausible regulations to cover for example, the provision of parks, cycle-ways, walkways and access to gyms and sports clubs.
Community wide campaigns: There is strong evidence from a systematic review of well-designed studies that these campaigns can increase physical activity levels when they are high intensity and sustained. Therefore, it is very plausible that regulations that improve access to physical activity opportunities will work synergistically with any future such campaigns conducted in the New Zealand setting.
Point-of-decision prompts to encourage stair use: A systematic review has found strong evidence from well-designed studies that these prompts can increase stair use. Such signs have not been widely used in New Zealand but regulations could be used to expand this approach with requirements for signage adjacent to lifts and escalators.
School-based physical education programmes: There is strong evidence from well-designed studies that these campaigns can increase physical activity levels and aerobic capacity. New Zealand has relevant physical education curricula and “walking school buses” are being increasing adopted, but detailed evaluation studies are lacking. There is a range of plausible regulations that strengthen the focus on sports that are more likely to be sustained throughout life (eg, tennis, golf, swimming and cycling).
Transportation policy and infrastructure changes to promote non-motorised transit: The largest review identified found that there is evidence that access to pedestrian facilities and walkways increases physical activity. This finding is compatible with that of the review described above that considered access to physical activity opportunities. Other evidence comes from countries that have achieved high levels of cycling for short trips eg, The Netherlands and Denmark. Given this evidence, many health authorities recommend action in this area (including WHO, IARC and New Zealand’s Public Health Advisory Committee). There is a range of plausible regulations that cover transport system decisions, the use of fuel taxes, and the expansion of cycle-ways and walkways.
Urban planning approaches: The largest review identified found that “accessibility, opportunities, and aesthetic attributes had significant associations with physical activity”. Other more recent work supports this association in terms of access to “walkable green spaces”. There is a range of plausible regulations that cover strengthening the roles of relevant health agencies in urban planning decisions; the expansion of parks, cycle-ways and walkways; requirements for car-free areas; the positioning of stairs in buildings; and even the enhancement of outdoor security via improved dog control.
Other possible regulations to promote physical activity: There are many other plausible regulatory interventions that were not reviewed in detail in this report. These include the use of economic instruments such as: congestion charging for traffic in inner city areas; taxing television airtime; levies on television airtime for specific sports; taxing video and computer games; taxing international visitors to fund walkways; incentives for employees who walk/cycle to work; tax reform to favour manual labour over automation; reductions in insurance premiums for physically active people; and making bicycles GST exempt.
Other possible regulatory interventions include: removing government support for television; requirements for television control devices on new television sets; adjustments to day light saving (to enhance outdoor activity); minimal requirements for health workers to dispense green prescriptions and subsidised pedometers; and requirements for regular “share the road” campaigns to make cycling safer.
There is good scientific evidence for a number of interventions to favourably modify the nutritional environment and to promote physical activity. Many of these interventions can be enacted through, or supported by, legislative and regulatory means. The revising of New Zealand’s Public Health Act can allow for the strengthening of the legislative framework that would permit better regulations for the prevention of obesity and chronic diseases such as diabetes.
1 Introduction Obesity and the coincident problem of type two diabetes have reached epidemic proportions globally2. In 1997 I was estimated that 120 million people were affected by type 2 diabetes and by 2010 the prediction was for the number to reach 216 million3. In some populations the problem is even more extreme. In our Asia-Pacific region for example, more than 70% of the adult Polynesian population in Samoa is considered obese4.
The causes of the global epidemic are multiple. Genetic factors explain most of the population variance in total-body and central abdominal fat mass in healthy postmenopausal white women5 and presumably others. They don’t however account for the temporal trend in obesity. Modernisation and acculturation result in reduced physical activity and a change to more energy dense diets.
Childhood Obesity Obesity clearly begins in childhood and in turn predicts obesity in adult life. After adjusting for parental obesity, the odds ratios for obesity in adulthood associated with childhood obesity ranged from 1.3 for obesity at 1 to 2 years of age to 17.5 for obesity at 15 to 17 years of age6. In New Zealand a study of 2273 Auckland school children aged between 5 and 11 years identified that 14.3% were obese (body mass index greater than the 95th percentile). The rate was highest in Pacific Island children (24.1%) with Maori having rate of 15.8% and European 8.6%7.
Obesity prevalence in children is increasing alarmingly. A survey conducted in Victoria, Australia compared weight and height measures of children aged 7 – 12 years in 1997 and 19858. There was a slight increase in height and substantial increases in weight over that time. These findings are consistent with a published report of a 100% increase in obesity in American children between 1980 and 19949. The rate of obesity in children has doubled over the past two decades and in adolescents it has almost tripled (from 5 to 14%). In the 2001, the US Surgeon General’s Report on Overweight and Obesity concluded that “left unabated, overweight and obesity may soon cause as much preventable disease and death as cigarette smoking”10.
Detrimental Health Effects and Risks Epidemiological studies show that obese individuals have a 50 to 100 percent increased risk of premature death from all causes11. Obesity is associated with an increased risk for coronary artery disease; type 2 diabetes; endometrial, colon, postmenopausal breast and prostate cancer; and certain musculoskeletal disorders such as knee arthritis as well as obstructive sleep apnoea.
The socio-economic ramifications of obesity are less easily quantified but are undeniably significant. For the individual there is a clear inverse relationship between weight and level of income. For the health care system and the economy of the country as a whole there are both the direct costs of health care and the indirect costs of wages lost through illness and premature death. Most of the costs are associated with type 2 diabetes, coronary heart disease and hypertension12.
Dietary Factors Laugeson and Swinburn 13 used Food and Agricultural Organization per capita food statistics to look at food supply and trends from 1961 to 1995. Compared to other OECD countries New Zealand had the highest ranking diet for predisposition to thrombosis, consuming the highest proportion of butter and meat fats. Although there has been a fall in the percentage of dietary energy derived from animal fats and alcohol over the decade, there has been an 8% increase in total energy consumption. This is clearly inappropriate in view of decreasing energy expenditure from physical activity.
Consumption of sugar-sweetened drinks by children is increasing. Over a 19-month period of observation of adolescents in the US, 57% showed increased intake with a quarter drinking one extra serving daily. Over the same period of time calorie intake increased and the incidence of new cases of obesity over the 19 month period was 9.3%.14 Currently, soft drinks constitute the leading source of added sugars in the American diet amounting to 36.2g daily for adolescent girls and 57.7 g for boys. These figures already approach or exceed the daily limits for total added sugar consumption recommended by the USDA and will certainly exceed the WHO recommendations for a maximum of 10% of daily intake to be derived from sugar.15
The report goes on to criticise the food and drinks industry for “heavy marketing practices of energy-dense, micronutrient poor foods”16
In addition to the effects of soft drinks on obesity, there is growing concern about the effects on children’s teeth. Despite fluoridation the NZ Dental Association is describing an increase in dental caries with an unprecedented need for dental extractions in preschool children. The combination of high sugar and low pH due to citric and phosphoric acids results in dental erosion. The addition of caffeine – as seen particularly in Cola drinks affects saliva directly and further compounds the problem17.
The impact of “fast” food is difficult to define precisely but there is no doubt that the increase in consumption of take-away foods represents a major dietary change. Americans now spend more money on fast food than on movies, books, magazines, newspapers, videos, and recorded music – combined. This has occurred in conjunction with a deliberate policy by advertisers to market products directly to children .In 1997 McDonalds advertised a Teenie Beanie Baby give-away with their Happy Meals. These meals are targeted towards 3 to 9 year olds. At that time McDonalds was typically selling 10 million Happy Meals a week but during the 10 days of the promotion they sold 100 million18.
In virtually all countries surveyed (Australia, Austria, Belgium, Denmark, Finland, France, Germany, Greece, the Netherlands, Norway, Sweden, the UK and the USA) there were more ads for food during kids’ TV than any other type of product, with ads for confectionery, breakfast cereals (mainly sweetened) and fast food restaurants making up over half of all food advertisements in the survey. In New Zealand, a review of advertisements shown on TV2 between the hours of 3.30 and 6.30pm on weekdays and from 8 to 11pm on weekends was conducted in 199919. It was found that of the 269 foods advertised, 63% were for foods that were too high in fat and/or sugar. The dietary pattern of the foods that were promoted was that of a diet which would lead to an increased risk of obesity and dental caries in childhood; and cardiovascular disease, diabetes and cancers in adulthood.