Many medical conditions and interventions require periods of bed rest in order to maximize
recovery and restore optimal physical function. Unfortunately, muscle becomes glucose
intolerant, bone starts to break down, and arteries become stiffer during sustained periods
of chronic inactivity, such as bed rest. Elevation of blood glucose during hospital stays
results in increased morbidity, mortality, length of stay and costs. Components of the
typical Western diet (refined carbohydrates and protein from animal sources common in
hospital foods) induce glucose intolerance, bone catabolism, and arterial stiffening;
plant-based proteins may not have the same negative impact. Pulses (i.e. low fat legumes:
lentils, chickpeas, beans, peas) contain carbohydrate with a low glycemic index, and do not
substantially increase blood glucose levels. At the same time, they are high in protein, but
do not contain the same sulphur-containing amino acid profile as animal proteins that induce
bone resorption. Pulses are, therefore, a potential 'super food' to mitigate many of the
negative impacts associated with required bed rest following medical illness.
The study purpose is to determine the effects of a pulse-based diet compared to a Western
diet of typical hospital foods on glucose tolerance, bone catabolism, and arterial stiffening
during bed rest. The investigators hypothesize that a pulse-based diet will be superior to a
typical Western diet for preventing glucose intolerance, bone catabolism, and arterial
stiffening during sustained bed rest.
Six healthy adults will take part in a cross-over study where they will be randomized to four
days of bed rest while on a pulse-based or Western diet, have a one month wash-out and then
cross-over before another four days of bed rest with the other diet. Immediately before and
after bed rest (i.e. the first morning after the last night of bed rest), oral glucose
tolerance tests will be conducted to assess glucose tolerance and insulin sensitivity (i.e.
markers used to assess diabetes risk). At the same time points, fasting blood samples will be
collected for lipid assessments. Urine will be collected for assessment of bone catabolism
(via measures of N-telopeptides: a by-product of collagen from bone which appears in the
urine when bone is breaking down). Blood pressure will be evaluated every two hours during
bed rest days from 9am to 9pm. Arterial stiffness (measured by the gold-standard technique of
pulse wave velocity using applanation tonometry) and beat-by-beat blood pressure will be used
to assess blood vessel function before and after four days of bed rest.
This study will inform improved hospital diets and nutritional habits of patients to prevent
or offset negative health implications during periods of bed rest that may be required either
in-hospital, long-term care or at home as part of standard medical care.
