In wealthy countries, unequal distribution of incomes has resulted in food poverty for a proportion of the population 2324. Paralleling this are undesirable and alarming health trends; rising obesity rates and incidence of diet-related chronic disease 2526 which result in reduced quality of life, loss of production and greater healthcare expenditure 2527. Furthermore, the majority of deaths in developed and developing nations are caused by non-communicable diseases where diet is a key risk factor 2829. There are well known socio-economic and ethnic disparities in rates of obesity and chronic disease; in developed countries, low socio-economic status and ethnicity is directly associated with overweight/obesity and chronic disease 30. The disproportionate representation of these groups in health statistics may be reflective of their poor dietary profile and an inability to meet recommended intakes or guidelines 31.

New Zealand has not been immune to the forces of globalization; the trends outlined above have also occurred there. Rates of overweight/obesity and chronic disease have increased in recent decades; the greatest burden falling on Māori (indigenous people) and Pacific peoples (immigrants from the Pacific and New Zealanders of Pacific ethnicity) and lower socio-economic groups 32. Obesity rates in adults doubled between 1989 and 2003 33 and currently 30% of children are overweight or obese 34. Nutrition-related risk factors account for a substantial proportion of the mortality and chronic disease burden and nutrition is second only to smoking as contributing to premature mortality 35.

Disparities in income have also increased in the previous two to three decades. Disposable income is almost three times greater for high-income earners compared to low-income groups and between 1998 and 2004 there was little change in (inflation-adjusted) incomes for those in the bottom income quintile 33. This is more marked for Māori; approximately 30% of all Māori fall into the bottom income quintile 36. Additionally, despite growth and adoption of policies consistent with economic globalization, the living standard for New Zealanders is currently 16% below the OECD median 37.

Food insecurity, "whenever the availability of nutritionally adequate and safe foods or the ability to acquire acceptable food in socially acceptable ways is limited or uncertain." 38, exists in New Zealand 24. Approximately one-fifth of New Zealanders can only sometimes afford to eat properly and over 22% report that they run out of food due to financial constraints; most affected are Māori and Pacific people and people in the lowest socio-economic group 39. The increased use of food banks in the same populations has also been recorded 40. Additionally, concern about household food security is more frequently expressed by individuals living in the most deprived areas compared with the least deprived 39.

A recent focus of concern in New Zealand with respect to food security has been the ability of consumers to purchase milk, an important nutrient source. This situation has the potential to contribute to adverse health outcomes as a result of inadequate intake of the micronutrients supplied by milk, particularly calcium. Adequate dietary calcium is essential for achieving peak bone mass in children and adolescents, particularly females, between the ages of 9 and 20. It is protective for age-related bone loss (osteoporosis) and subsequent risk of bone fracture 414243. More recently, dairy consumption has also been associated with reducing the prevalence of the metabolic syndrome in men 4445 and Type II diabetes and cardiovascular disease younger adults 46.

Recent national nutrition surveys reveal that dietary guidelines and recommended intakes for milk may not be met by the whole of the population. For children, milk is the predominant source of dietary calcium but only 38% of children consume milk daily and 34% weekly 34. Disturbingly, 17% reported they did not drink milk at all or if so, then less than monthly. New Zealand European children proportionally consume more milk than Māori and Pacific children 34. Reflecting milk intake, 15% of children had inadequate dietary calcium intake, higher in adolescents and females compared to younger children and males. Pacific children had a higher rate of inadequate intake than Māori or European children 34.

Milk consumption is low among adults, one study 47 reported that 9.4% of young adults (16–30 y) did not consume milk and one-third consumed less than a glass a day. Non-consumption was generally higher in women than men. Nationally, the prevalence of inadequate intake of dietary calcium is estimated to be 20%. However, inadequate dietary calcium intake is higher and more prevalent in females, the 15 – 18 year old age group and Māori 39. In terms of equity, milk consumption, and thus dietary calcium intake, has been shown to be directly related to socio-economic status 31 and in New Zealand, intake of nutrients supplied by dairy products was most compromised in the most deprived quartile 39.

Additionally, and of greater concern, are a number of international studies 484950515253 reporting that as age increases, the consumption of other beverages, especially sodas, also increases, to the detriment of milk consumption. The health consequences of beverage substitution includes an increased risk of osteoporosis due to nutrient displacement 5254 and increased risk of dental caries due to high added-sugar content 355. Further, an overwhelming body of evidence supports the direct relationship between increased intake of sugar-sweetened beverages and obesity resulting from greater energy intake and associated poor diet patterns 352565758, a situation with significant consequences for health.

Studies specifically investigating beverage substitution have not been conducted in New Zealand though its occurrence would not be an unreasonable assumption. The only national children's nutrition survey (in 2002) 34 reported that almost half of New Zealand children consume soft drinks, cola, and powdered fruit drinks and fruit juice on a weekly basis. The highest consumption being in the 11–14 year age-group, Māori and Pacific and the most deprived children. Similar trends have been reported in the 2006/07 New Zealand Health Survey 59; 20% of children aged 2–14 had three or more 'fizzy' drinks per week, with half of those having five or more. The highest consumption was reported in the older age groups, Māori and Pacific peoples; consumption rates were significantly higher in the most deprived neighborhoods.

An important precursor to the developments presented may be traced to market-orientated economic reforms 6061 which commenced in 1984. Prior to the reforms, New Zealand's economy was one of the most regulated and protected in the world but rapidly transformed into one of the most open and liberalized 6061. Consistent with economic globalization, general reform measures included removal of government subsidies, reduction of import tariff and non-tariff barriers, removal of controls on interest rates, wages and prices, restructuring and sale of government assets and reform of tax structures including the application of a neutral goods and services tax (GST) in 1986 60. Individual sectors of the economy were also reformed, the first being the cornerstone of New Zealand's economy, the agricultural sector. The events which occurred in the dairy industry were to have repercussions for milk consumers in New Zealand.

As it relates to the food system, globalization includes the redefinition of 'market' from local to global and changes in power and focus of food governance, culture and ideology 73747576 giving rise to a situation where it has become cost-effective to consume foods which contribute to unhealthy eating behaviours 77. The changes also facilitate an imbalance between rich and poor regarding the development of dietary patterns 78. Mediated by economic globalization an inequitable situation arises, the increasing availability of cheap foods forces the financially constrained towards nutritionally poor foods and an obesogenic diet, whereas the wealthy, through the financial benefit of choice, have access to a market supplying more expensive healthier foods and products 7879.

Price is a major determinant of food choice and purchasing 808182 which, in turn, reflects food and nutrient intake 8083. Studies show that due to economic constraints, low-income earners generally select cheap, energy-dense foods and diets 7984. Thus, for people on low incomes, economic resources and purchasing power determines the ability to be able to achieve good diet quality 7984 and though not equivocal, it has been reported that for low-income earners, purchasing foods to achieve recommended dietary guidelines is, or is perceived to be, costly and difficult 858687.

In New Zealand, the removal of government subsidies and price-control measures, the application of GST and the linkage of retail prices to export commodity prices (in turn influenced by global demand and supply), have contributed to milk, a 'core' beverage (that is, included in the nutritional guidelines) increasing in price. Furthermore, milk now directly competes with cheaper, nutritionally-poor, 'non-core' beverages (such as SSCBs) which are widely available and competitively priced. The rationale for milk purchasing behaviour in New Zealand has yet to be definitively determined. However, Wham & Worsley 47 reported that when questioned about attitudes to milk, New Zealand respondents stated "milk is more expensive than fizzy". Despite being aware of the nutritional implications of their purchase, this may indicate that, due to price, some milk consumers preferentially choose sugar-sweetened carbonated beverages (SSCBs) over milk.

Figure 1 shows milk and SSCB pricing trends over time; a steady increase in retail milk price has been accompanied by decreasing retail cost of SSCBs. Up to 1990 – 92, milk was cheaper (per litre) than SSCBs. However, the trend reversed at that time and SSCBs became, and have continued to be, cheaper than milk. This is significant as the high cost of milk relative to SSCBs may heighten income-based disparities in accessing healthier diets and contribute to unequal health outcomes. The reduction in pricing of SSCBs can also be attributed to the general economic reforms of the mid-1980s, most likely as a result of the removal of import tariffs and encouragement of investment by multi-national companies in New Zealand. Reflecting these events, supply figures during the period 1969–1996 indicate a substantial increase in SSCB production in New Zealand from 1988 onward 88.

With respect to milk, there have been significant reductions in the supply of dairy products to the New Zealand domestic market. In recent decades supply has dropped from 700 g/day in the 1970s and 1980s, to 235 g/day currently 89. This figure includes other dairy products such as cheese and butter and may be reflective of a reduced demand in these foods resulting from changing diet patterns. Nevertheless, it accompanies reports indicating a decline in milk intake of almost one-third during the 1980s and 1990s 90.

Another feature of globalization, the emergence of large supermarket chains 757678 may have also contributed to altered pricing and availability of milk and SSCBs. Due to their bulk purchasing power and control of food supply chains, supermarkets provide access to a greater variety of food with poorer nutritional quality at cheaper prices 237891. Rather than being considered as a core nutrient source, milk now competes side-by-side as a beverage with SSCBs (and other beverages) in supermarkets. Additionally, the SSCB industry has aggressive and powerful marketing and advertising strategies relative to milk (the reported advertising spending for SSCBs in New Zealand in 2005 was almost twice that of milk 89) resulting in a strong, albeit undesirable, exposure and access to their product 759293.

Furthermore, it is most likely the limited purchasing points for milk and the demise of home delivery service have resulted in poorer consumer access to milk. Milk vending (now only commercial), reduced by almost one-third between 2000 and 2005 89. Once a feature of the domestic supply organization prior to economic restructuring, home delivery ensured all households had equal and ready daily access to milk.

Overall, the information adds credibility to the hypothetical pathway proposed in this paper. The apparent reductions in milk supply and consumption, along with changing consumption patterns (such as beverage substitution) have paralleled, and are most likely a consequence of, the New Zealand economic reform measures of the 1980s. Economic globalization forces in New Zealand have potentially affected nutrition and health both directly and indirectly in the case of milk, primarily by creating an environment which is neither equitable nor conducive to healthful behaviours. Figure 2 illustrates the proposed hypothetical pathway (based on Woodward et al 1) linking globalization with adverse health outcomes and health inequalities as a result of changes in milk availability and pricing. The intermediary levels include the effect of national economic policies on population-level and individual health risk behaviours as well as household economies and resources. (Figure 2).

Milio 94 recommends a "broad spectrum of approaches at the policy level" be taken to create environments conducive to healthful nutrition and improved health outcomes; that is, healthy public policy. To realize this recommendation and ensure the consequences for health are taken into consideration, Woodward et al's 1 conceptual framework can be used as a foundation for policy development. Therefore, the hypothetical pathway (Figure 2) presented in this paper could be used to identify foci for policy and programme development which improve the environment for milk consumption at community, national and international levels. Though New Zealand currently has policies and programmes in place addressing the issue of nutrition and food insecurity, they have limitations and are often aimed at the individual health risk level. Other policy solutions focusing on the upper tiers of the proposed pathway may be of greater benefit and should be given consideration.

Food choice and purchasing is complex and determined by many factors 8081. So as to ascertain the specific repercussions for health, better inform policy and support the hypothetical pathway presented in this paper, further research is required to understand the economic, geographic and social reasons for food choice in New Zealand, particularly in low-income and at-risk groups. Further national nutrition surveys are essential to provide comparative data and contribute to the understanding of food and beverage consumption and dietary intake patterns. Though this paper concentrates on milk, other recommended foods, such as fruits and vegetables, may be similarly influenced by the factors discussed and warrant investigation.

Specifically, research is required to understand the rationale behind milk and alternative beverage purchasing behaviors, including pricing and availability. However, price and availability may not be the only reasons for reduced milk and dietary calcium intake 123. In women particularly, it may be due to messages concerning the health implications of consuming full-fat milk 124. Changes in diet patterns such as increased consumption of food away from the home 89 and in children, reduced breakfast consumption 125126, may also have some bearing.

The complexity of the globalization and health relationship and its intricate and non-linear pathway means that it may not always be possible to gather conclusive evidence to inform policy. Thus, the standard for burden-of-proof may need to be re-evaluated. The evidence base may have to be more mixed and rely on quantitative and qualitative research, ranging from observation and case studies through to clinical evidence-based research 127128129.