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| Journal of the New Zealand Medical Association,
19-March-2010, Vol 123 No 1311
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Delvina Gorton, Julie Carter, Branko Cvjetan, Cliona Ni
Mhurchu
Snack vending machines are part of an obesogenic environment
that promotes easy access to energy-dense, nutrient-poor foods. Typically,
vending machines offer few healthy options.1
Thus, they make the unhealthy choice the easy choice, which is contrary
to the goals of public health nutrition.2 They
are therefore an appropriate target for interventions to improve the nutrition
environment.
Previous research has examined the effect of reduced price
and/or promotion of healthier choices in vending
machines.3-7 However, no studies to date have
assessed the impact of vending nutrition guidelines on the nutrient profile of
products sold from vending machines.
Nutrition guidelines have been used in a variety of
interventions and situations. Positive effects have been seen in schools in the
United States. Implementation of nutrition guidelines has lead to increased
proportion of snacks meeting guidelines stocked in vending
machines,8 decreased consumption of snacks with
low nutritional value,9 and decreased
purchasing of less healthy meals.10
Recent research on the feasibility of point-of-purchase
interventions strongly recommended pilot studies which examine sales figures,
consumer satisfaction, and practical feasibility prior to
implementation.11 This pragmatic community
intervention study aimed to assess the effect of implementation of healthier
vending guidelines on the nutrient content of products sold, sales, and customer
satisfaction.
Specific objectives were to develop nutrition criteria for
vending machines (Better Vending for Health [BVFH]
guidelines)12 and assess their effect on the
amount of energy, total fat, saturated fat, sugar and sodium sold from snack
vending machines; measure total product sales; and assess staff satisfaction
with vending machine product choices. Vending machines selling beverages were
excluded.
MethodsStudy setting—The study was
carried out at two hospital sites in Auckland, New Zealand (North Shore Hospital
and Waitakere Hospital) between March 2007 and May 2008. Hospital vending
machines were accessible by staff and some visitors. Staff working at the
hospitals included administrators, managers, health professionals, cleaning and
catering staff, security, and clerical staff. At baseline 4700 staff (4000 Full
Time Equivalent positions [FTE]) worked at the two hospitals.
Study phases—There were three
phases to the study: development of nutrition criteria; staff surveys
pre-intervention and midway through the intervention; and collection and
analysis of 3 months of vending machine sales data pre-intervention and
post-intervention. Sales data were linked to a specially compiled nutrient
database of vending snack products. The Northern X Regional Ethics Committee
stated that ethical approval was not required for the study.
Nutrition criteria development (BVFH
guidelines)—Nutrition criteria for the BVFH guidelines were
developed by eight nutrition professionals representing local District Health
Boards, the Auckland Regional Public Health Service, the National Heart
Foundation of New Zealand, and the University of Auckland. The nutrition
criteria (Figure 1) focused on energy, saturated fat, sodium, and portion sizes
of confectionery. They were based on existing New Zealand food and nutrition
guidelines and classification systems, including the Food and Beverage
Classification System for schools, and modelling of the discretionary energy
allowance for snacks.
Two levels of classification were developed:
‘better’ and ‘other’ choices. Products had to meet one
of these classifications to be stocked in vending machines, and the ratio of
’better’ to ‘other’ choices could be adjusted to suit
individual workplaces. To be a ‘better choice’ item, foods were
required to contain ≤800kJ per packet, ≤1.5g saturated fat per 100g,
≤450mg sodium per 100g, and not be confectionery. ‘Other
choice’ items were only required to meet the energy criteria
(≤800kJ/packet).
Preliminary modelling work was conducted to assess how
many current vending snack foods met the criteria, to ensure foods were
classified in a way that was consistent with foods generally considered as
healthier options, and to ensure the guidelines were appropriate and feasible.
The guidelines were intended to be simple and straightforward to facilitate use
by vending contractors, and able to be written into the vending contract. The
vending contractor was trained how to use the guidelines, and was responsible
for ensuring machines were stocked correctly.
In this study, vending machines were stocked with 50%
better choices and 50% other choices. Examples of ‘better choice’
vending items included small packets of rice crackers, dried fruit, tuna and
crackers, dried fruit bars, and soup mix sachets. ‘Other choice’
items included finger-sized chocolate bars, small cookies (30g) with reduced
saturated fat content (1.5g), lower fat potato chips, some puffed snack
products, some muesli bars, and small packets of confectionery.
‘Other choices’ were included in the
guidelines because of limited availability of products for vending machines that
met ‘better choice’ guidelines. Furthermore, it was recognised that
allowing inclusion of some ‘treat’ type foods would provide more
flexibility for individual worksites adopting the guidelines. The 800kJ cap on
‘other choices’ ensured that these treat foods were in appropriate
serving sizes, and eliminated the traditional vending range of high-energy
foods.
Figure 1. Criteria for snacks sold through
vending machines (Better Vending for Health guidelines) at two hospital sites in
Auckland, New Zealand in 2007-08
* For packets containing more than one serve of an
item, it is the packet size (not the serving size) that must meet these
guidelines.
Implementation of
guidelines—BVFH guidelines were gradually phased into all vending
machines at the two main hospital sites over a 2-month period. Products meeting
the criteria were identified from the existing vending contractor’s
product range, and additional suitable products were also sourced. An
implementation manual was developed for vending contractors to provide guidance
on how to identify suitable products.
The guidelines were introduced as part of an overall
District Health Board (DHB) workplace food and nutrition policy that was in the
process of being developed and implemented. Under the same policy, sugary
beverages had previously been removed from DHB beverage vending machines. Staff
were informed of planned changes to vending machines in a monthly staff
newsletter, following a baseline staff survey. Vending products were not
signposted in the machine as ‘better’ or ‘other’
choices.
Staff surveys—Two staff surveys
were conducted: one before and the other midway through the intervention phase.
Surveys were web-based, and staff were informed of the survey by email. The
surveys assessed where staff usually obtained the food they ate at work,
frequency of snack vending machine use, reasons for non-use of vending machines,
food usually purchased from vending machines, number of items purchased, whether
staff tried to choose healthier items, satisfaction with vending machines,
suggestions for additional foods they would like in vending machines, and
socio-demographic data.
The second survey, during the intervention period, also
assessed self-reported change to vending machine purchases following
introduction of the BVFH guidelines.
Sales data—Sales data (the
number of items re-stocked) were collected from all snack vending machines
across two hospital sites (n=14 machines). In addition, a stocktake of each
vending machine was completed at the beginning and end of the data collection
period. During the stocktake the quality of data collection was monitored and
stock was checked for compliance with the guidelines.
Baseline (pre-intervention) sales data were collected
for 3 complete months from March to May 2007 and intervention sales data were
collected 1 year later from March to May 2008. This time period was chosen to
minimise seasonal variation in vending machine purchases. The changeover to
healthier vending options was carried out gradually over a 2-month period
(October to November 2007).
Sales data were linked to a nutrient database, which
contained the energy, total fat, saturated fat, total sugars, and sodium
contents of vending products based on the mandatory nutrition information panel
information on their packaging.
Study outcomes and analyses—The
primary outcome was the effect of the intervention on energy density (kJ/100g)
and energy per packet (kJ). Secondary outcomes were sales of total fat,
saturated fat, sugars and sodium per 100g of food sold from vending machines;
change in machine sales (absolute amount and dollar value); and staff
satisfaction.
Product nutrient and sales data were entered into an
Excel spreadsheet and extracted into SAS Version 9.1 for analysis.
Descriptive analyses were undertaken for both sales data and staff surveys.
Measures of variability (e.g. confidence intervals) were not calculated for
sales data due to the clear difference in outcomes following intervention.
Total sales value ($) over the 3-month baseline and
intervention period were estimated by multiplying product price by number of
items sold per product. The price of products at the start of intervention was
used for both baseline and intervention price calculations to avoid confounding
due to price increases between assessment periods.
Data from the first stocktake at the beginning of the
baseline period could not be used due to missing data. However, monthly
stocktakes were conducted throughout, and the stocktake from the end of the
first month was used as a surrogate starting point for the baseline stocktake.
In order to determine whether this made a difference to sales results, a
sensitivity analysis was conducted. Sales volumes were also estimated based on
number of products restocked only (starting and end stock were not included) as
a surrogate for sales.
ResultsStaff surveys—The baseline web survey
was completed by 18% of all DHB staff (n=835); 84% were female, 57% were health
professionals, and 82% were NZ European or Other ethnicity (non Māori,
Pacific or Asian), with a mean age of 43 years. The follow-up survey was
completed by 13% of all DHB staff (n=611), with similar demographics to the
baseline survey, which are generally representative of the staff population (80%
female, average age 44 years13).
Most respondents either never or
infrequently used vending machines (84% at baseline, 85% at
intervention). Vending products preferred by machine users were chocolate and
potato chips/crisps, and most users only bought one item at a time (84% and
85%). At least half (51% and 53%) claimed to try to choose healthier items. At
baseline, 27% of staff who used vending machines were somewhat or
very satisfied with the vending range, and this increased to 46%
post-intervention.
After introduction of the BVFH guidelines, 87% of staff who
used vending machines had noticed healthier snacks were available. Forty-seven
percent thought the range had improved, 27% thought it was about the same, and
26% thought the range was worse. One-tenth (11%) reported they now used vending
machines at work more frequently. Over half (54%) of the staff who used vending
machines had changed their choices, with one-third (31%) reporting this change
was in order to make healthier choices.
Sales data and effect on nutrient content of
products sold—During the 3-month baseline period, 13,749
individual items of food were sold (611 kg total weight) through snack
vending machines. In the post-intervention period, 17,425 items (611 kg) were
sold, an increase of 3676 items. Total weight (kg product sold) did not change,
as some products were sold in smaller-sized packets. Staff numbers also
increased over the same time period, by around 400 FTE. When taking staff
numbers into account, 3.4 items were purchased from vending machines per FTE
over the 3-month baseline period. During the intervention period, 4.0 items were
purchased per FTE, giving an average increase in sales of half a packet (0.5
items).
Implementation of the BVFH guidelines decreased average
energy content per product sold from 939kJ per packet to 563kJ per
packet—a 40% reduction (Figure 2). Per 100g, average energy content
reduced by 24% to 1606kJ/100g. The average total fat content per 100g of
products sold reduced by 32% (from 28g/100g to 19g/100g) (Figure 3).
Saturated fat also reduced, by 41% to an average of 7g/100g,
primarily due to removal of most cookies and some potato chip/crisp varieties.
This level is higher than the ‘better choice’ guideline threshold of
≤1.5g/100g because only 50% of products stocked were ‘better
choices’, and ‘other choices’ did not have a specified
saturated fat threshold. The average percentage of total sugars in products sold
decreased by 30%.
Figure 2. Change in the amount of energy per
100g and per packet sold through vending machines at baseline (2007) and
post-intervention (2008)
 Figure 3. Change in fat and total sugars per
100g product sold through vending machines at baseline (2007) and post
intervention (2008)
 Sodium was the only nutrient that did not show changes in
the direction expected (Figure 4). Overall, levels stayed within the guidelines
for ‘better choices’ (<450mg/100g). However, there was an overall
increase of 101mg/100g (29%) sodium in products sold. This increase was largely
due to increased sales of puffed snack and potato chip/crisp products.
Figure 4. Change in sodium per 100g product
sold through vending machines at
baseline (2007) and post-intervention
(2008)
 The top-selling items (over 500 items sold) during the
intervention were reduced-fat chips and puffed savoury snacks, small chocolate
bars, small reduced-fat cookies, small packets of lollies, and rice crackers. Of
the ‘better choice’ options, as well as rice crackers, apple crisps
(n=328 packets sold), tuna and crackers (n=316), dried fruit (n=232), and soup
mixes (n=200) were the most popular items.
Between baseline and post-intervention, the total sales
value increased by a total of NZ$1538. Per staff FTE, sales over the 3-months
were NZ$5.70 for baseline sales and NZ$5.53 post-intervention. The average price
per item sold at baseline was NZ$1.66 and the average price per item sold under
the BVFH guidelines was NZ$1.40. The reduced price was due to the lower cost of
smaller packet sizes, especially the chocolate bars. Some ‘better
choice’ items in the intervention were more expensive than average, such
as cooked rice meals ($3), and tuna and crackers ($2.50). Potato chip/crisps and
puffed savoury snacks remained the same price.
DiscussionThis study examined a pragmatic intervention aimed at
improving the food environment by introducing healthier snack choices into
workplace vending machines. Introduction of the BVFH guidelines led to a
substantial decrease in energy, total fat, saturated fat, and sugars sold
through vending machines. Over a 1-year period, this was equivalent to the
removal of approximately 12,400MJ, 210kg of total fat, 130kg of saturated fat,
and 220kg of sugars from vending machines at these sites.
Furthermore, machine sales did not decrease (which is an
important consideration for vending contractors), and staff reported improved
satisfaction with the vending range. Thus, implementing the BVFH guidelines more
widely could make a small but important difference to the diet of people who
frequently buy snacks from vending machines.
This research adds to the existing body of evidence on
vending machines by showing the effectiveness of nutrition guidelines. To date,
much vending research has focused on pricing or promotion
interventions.5,6,14-16 Lowering the price of
healthier options, however, appears to lead to increased sales of both healthier
and less healthy options.5
Likewise, promoting healthier choices may increase sales of
both healthy and less healthy choices.15 The
current study did not use promotions or price discounts to encourage
‘better choices’, and instead focused on assessing the effect of
increased availability of healthier options, and elimination of products that
did not meet the BVFH guidelines.
Whilst introduction of the BVFH guidelines resulted in
beneficial changes in most nutrients, the sodium content of products sold
post-intervention increased, mainly due to potato chip/crisp or puffed snack
sales. As these were a top-selling item, vending machines were stocked with a
wide selection. There can be substantial variation in sodium content between
flavours in a product range and between crisp or puffed snack products.
Including flavours or products with lower sodium contents could therefore
potentially reduce the amount of sodium sold. Consideration could also be given
to introducing sodium criteria for ‘other choices’. Nevertheless,
average sodium remained below the guideline threshold and the overall impact of
the BVFH guidelines on nutrition was still largely positive.
Introduction of the BVFH guidelines did not result in any
substantial changes to usage of vending machines or amount of product purchased.
Whilst one-tenth of vending machine users reported that they were using vending
machines more frequently, one-third used them less often, and the overall usage
remained very low (85% of staff infrequently or never used vending machines).
Average sales per staff member only increased by half a
packet over the 3 months, with no change in total weight of product sold. Whilst
there was an increase in total sales value, this may have been largely driven by
an increased staff FTE. If the FTE had not increased, total sales value may have
decreased due to the lower average price per item, due to smaller packet sizes.
There was demand from around half of the staff who replied to the survey for
healthy options to be supplied in vending machines, although a minority opposed
changes.
The BVFH guidelines served to introduce a range of healthier
options for those who previously did not have that choice, whilst still
providing some ‘treat’ type options in appropriate serving sizes. It
has been said that to succeed in changing diets, healthier foods must first be
available,17 and the BVFH guidelines assisted
in increasing availability in vending machines.
Of the nine products that sold over 500 items in the 3-month
intervention period, only one was a ‘better choice’ item (rice
crackers). The remaining items were ‘other choice’ products. Thus,
there is potential to improve the range of ‘better choice’ items to
increase demand, although there are currently limited options from which to
select, mainly because products are often made in specific packet sizes for
vending machines.
Should the BVFH guidelines be implemented widely across
worksites, schools and other locations in New Zealand, they should provide an
incentive for food manufacturers to reformulate products to meet ‘better
choice’ criteria, thus improving the range of options available. Some
manufacturers have demonstrated willingness to reformulate to meet nutrition
guidelines such as these, as was the case following introduction of national
nutrition guidelines for food and drinks sold in schools in New
Zealand.18 As a wider range of ‘better
choice’ products become available, the ratio of ‘better’ to
‘other’ choices stocked in vending machines can be increased to
provide more ‘better choice’ options.
Successful implementation of the BVFH guidelines depends on
active participation of both worksites and vending contractors. For this study,
initial support for the vending contractor in identifying suitable products was
provided by a public health dietitian at the DHB. Similar support could be
provided by public health organisations to assist worksites and vending
contractors in successfully implementing the BVFH guidelines elsewhere.
Vending machines are likely to remain a part of the
nutrition environment. This study therefore provides some reassurance to vending
contractors and host institutions regarding the feasibility and acceptability of
introducing healthier products into vending machines, in the context of the
limitations discussed below.
These results should be used to support the implementation
of the BVFH guidelines on a wider scale. Examples of suitable venues would be
schools that host vending machines (in combination with the Food and Beverage
Classification system), leisure facilities such as gyms, and other worksites.
Further research into the additional effects of price and/or promotion
interventions on sales in vending machines with the BVFH Guidelines would be
useful.
Study limitations and strengths—The
strengths of the study include its assessment of the implementation of healthier
vending criteria in a real-world setting; its multi method design; the use of
sales data as a robust, objective measure of effect; and the extended length of
time over which sales data was collected, which minimised any effect of seasonal
variability.
The staff survey achieved very low response rates and cannot
be considered representative; however, demographics of respondents did not
appear to differ substantially from the general hospital staff population (in
terms of sex, age, profession, and ethnicity). The study was also conducted in a
hospital/health provider setting, and thus results may not be generalisable to
all workplaces. Nevertheless, staff at the hospitals comprised a diverse range
of health professionals, administrative, clerical and manual workers.
Price changes could potentially have influenced sales, but
this likely worked in both directions. Prices for some of the products reduced
due to smaller packet sizes, some remained the same, and others increased.
Finally, we did not assess dietary intakes so cannot
estimate the impact of the intervention on overall dietary intake of
individuals. It is possible that some compensation may occur at other times of
the day that could minimise the overall impact of the vending
intervention.
ConclusionIntroduction of healthier vending guidelines led to improved
nutrient profile of products sold through worksite vending machines, increased
staff satisfaction with the product range, and had no adverse impact on total
sales. The results show such guidelines are feasible and acceptable for both
consumers and vending contractors. Similar interventions with a wider reach are
indicated.
Competing interests: None known.
Author information: Delvina Gorton,
Dietitian / Research Fellow, Clinical Trials Research Unit, University of
Auckland; Julie Carter, Dietitian, Healthy Lifestyles Team, Funding &
Planning, Waitemata District Health Board, Auckland; Branko Cvjetan, Dietitian,
Healthy Lifestyles Team, Funding & Planning, Waitemata District Health
Board, Auckland; Cliona Ni Mhurchu, Public Health Nutritionist/Programme Leader
(Nutrition & Physical Activity), Clinical Trials Research Unit, University
of Auckland
Acknowledgments: The study was completed
with the support of Waitemata District Health Board, and funding from Public
Heath Operations at the Ministry of Health. Our thanks go to the vending
contractor and the vending company for their work in expanding the range of
suitable vending products, and for the extra work undertaken in recording sales
data and stocktakes.
The BVFH guidelines* were developed by Julie Carter from
Waitemata District Health Board, Penny King and Kate Sladden from Auckland
District Health Board, Franica Yovich from Counties Manukau District Health
Board, Elizabeth Stewart from Auckland Regional Public Health Service, Dave
Monro from the National Heart Foundation, and Cliona Ni Mhurchu and Delvina
Gorton from the Clinical Trials Research Unit at the University of
Auckland.
*A copy of the guidelines are available at: http://www.arphs.govt.nz/promoting_health/downloads/BVFH%20A4%20Booklet%20-%20FINAL%20-%20110108.pdf
Correspondence: Cliona Ni Mhurchu, Clinical
Trials Research Unit, University of Auckland, Private Bag 92019, Auckland Mail
Centre, Auckland 1142, New Zealand. Fax: +64 (09) 3731710; email: c.nimhurchu@ctru.auckland.ac.nz
References:
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