INTRODUCTION
The global burden of diabetes is on the rise. The World Health
Organization (WHO) estimated that 422 million adults were living with
the disease in 2014, a number that has nearly doubled since 1980 (22).
Sustained hyperglycemia ultimately increases one’s susceptibility to
cardiovascular disease and other health complications. It seems
pertinent to investigate therapies which may lessen the disease burden
of diabetes at the individual and population level.
The earliest experimental studies of vinegar’s health benefits
demonstrated that acetic acid and vinegar have inhibitory effects on the
rapid increase in blood glucose concentrations following sucrose
ingestion (7). Ebihara et al investigated blood glucose and insulin
responses to a 300ml sucrose solution with and without the addition of
60ml strawberry vinegar (5% acetic acid). Notably, the time to attain
maximal glycemic response was delayed in the vinegar condition.
Furthermore, the area under the insulin response curve was 20% smaller
in the vinegar-containing test meal. These early experimental studies
provided evidence that vinegar may exert potent anti-glycemic effects
when consumed with a glycemic load.
The antiglycemic benefits of vinegar have been demonstrated in healthy
subjects with normal glucose control (3,8,18) and insulin-resistant
subjects (11,21). Those with impaired glucose tolerance or insulin
resistance have shown long-term supplementation with vinegar reduced
HbA1c values by 0.16% (21) and improved insulin sensitivity by 34% via
a mechanism proposed to work similar to the drug metformin (11). A
dose-response relationship for blood glucose and serum insulin
concentrations after a bread meal have been observed, noting that 28
mmol acetic acid significantly lowered blood glucose and insulin
compared to lower doses (18). In fact, the ability of vinegar to lower
postprandial glucose excursions may be its most potent quality, as
isolated postprandial hyperglycemia has been demonstrated to increase CV
mortality, even in the absence of impaired fasting glucose.
Aerobic exercise is well-known to benefit glucose control. (6,7,9)
Research has shown duration and timing (pre-vs. post meal) of exercise
to be factors in the extent to which glucose is controlled. Dipietro et
al. observed that a single bout of 15 minutes of walking performed 30
minutes post-meal was effective in improving 24-hour glycemic control in
insulin resistant subjects and reducing glucose levels 3 hours post-meal
(6). This highlights the need to verify if pre-meal exercise can benefit
postprandial glucose.
Currently, the efficacy of pre vs. postmeal walking has not been
established. No studies to date have compared a bout of post-meal
walking with other glucose control strategies such as pre-prandial
vinegar ingestion. Therefore, the aim of the present study was to
compare the efficacy of a mass-relative dose of pre-prandial vinegar to
a 15-minute bout of self-paced treadmill walking in reducing
postprandial response to high-glycemic meal in glucose-intolerant
participants. We hypothesized that 15 minutes of postprandial walking
and preprandial vinegar ingestion would both reduce postprandial
glycemia. However, we expected that a larger reduction would be observed
with postprandial walking.