A Trial on the GI of Spaghetti Versus Rice as Mixed Meals
Condition: Dietary Modification
Study type: Interventional

Summary: 
      Pasta and rice are two of the most commonly consumed grains worldwide, where the former has a
      low GI (e.g. spaghetti) and the latter, usually (as it depends on the type) has a higher GI
      (e.g. white rice). The most typical ways in which pasta and rice are consumed are with the
      addition of oil or tomato sauce, and are recommended to be consumed in this way in the
      Mediterranean diet. The Mediterranean diet has been demonstrated to reduce the risk of
      cardiovascular disease, improve glycemic control and is encouraged in many clinical
      guidelines globally for both cardiovascular risk reduction. Some studies have explored the
      differences in glycemic response of different carbohydrate foods consumed with the addition
      of fat demonstrating that the glycemic response is indeed reduced.However, the GI may remain
      of importance even when other means to reduce glycemic response are introduced.

      The investigators therefore designed a randomized controlled crossover study to explore
      whether the addition of fat in the form of commonly consumed sauces which are recommended as
      part of a Mediterranean diet, affects the difference in glycemic response between a commonly
      consumed low GI and a higher GI carbohydrate food.
    

Detailed description: 
      Background:

      Pasta and rice are two of the most commonly consumed grains worldwide, where the former has a
      low GI (e.g. spaghetti) and the latter, usually (as it depends on the type) has a higher GI
      (e.g. white rice). Low GI foods have been demonstrated to improve glycemic control, insulin
      sensitivity and diabetes management, and have been associated with reduced risk of chronic
      disease, including coronary heart disease. Therefore, GI is of importance as a potential
      dietary strategy to reduce postprandial glycemia and improve glycemic control, particularly
      with the increasing rates of diabetes.

      Several studies have demonstrated how the addition of fat to a meal can reduce the glycemic
      response, some of which have suggested in a dose response manner. The mechanism by which
      increasing fat reduces the glycemic response may be through the effects on gastric emptying.
      Fat may modulate the gut hormones cholecystokinin (CCK) and peptide YY, which delay gastric
      emptying, which is known to be a major determinant of postprandial glycemia where small
      changes can have a substantial effect. Low GI foods result in lower glycemic excursions
      compared to higher GI foods, which, in addition to gastric emptying, may exert this effect
      through various pathways. Thus, there is importance of exploring the potential additional
      benefit beyond reducing the glycemic response with the addition of fat.

      The most typical ways in which pasta and rice are consumed are with the addition of oil or
      tomato sauce, and are recommended to be consumed in this way in the Mediterranean diet. Among
      many benefits, the Mediterranean diet has been demonstrated to reduce the risk of
      cardiovascular disease, improved glycemic control and is encouraged in many clinical
      guidelines globally for both cardiovascular risk reduction and for diabetes. Some studies
      have explored the differences in glycemic response of different carbohydrate foods consumed
      with the addition of fat demonstrating that the glycemic response is indeed reduced.However,
      the GI may remain of importance even when other means to reduce glycemic response are
      introduced.

      The investigators therefore designed a randomized controlled crossover study to explore
      whether the addition of fat in the form of commonly consumed sauces which are recommended as
      part of a Mediterranean diet, affects the difference in glycemic response between a commonly
      consumed low GI and a higher GI carbohydrate food.

      Objective:

      To assess whether the addition of fat to a low GI and higher GI carbohydrate food lowers the
      glycemic response equivalently, thus whether the difference between the low and higher GI
      food is preserved.

      Scope:

      The principal scope of the study is to evaluate the impact of two carbohydrate-containing
      foods varying in glycemic index, spaghetti and rice, on postprandial glucose.

      To confirm that the two foods vary in GI, the GI of the rice will first be tested in Part A,
      since the GI of spaghetti has already been determined in the investigator's lab.

      In Part B of the study, following the consumption of the test foods by healthy volunteers
      (see Study Design), the investigators will evaluate the differences in postprandial glucose,
      as well as insulin and c-peptide.

      Implications:

      These results will determine whether there is an independent effect of the GI of a
      carbohydrate containing food when fat is added to a meal in the context of how is it commonly
      and recommended to be consumed. These results may be useful to encourage the use of low GI
      foods for greater improvements in glycemic and insulinemic control, which is an important
      public health concern in today's global society.
    

Intervention name(s): Glucose #1; Glucose #2; Glucose #3; Spaghetti; Rice; Spaghetti + Tomato Sauce; Rice + Tomato Sauce; Spaghetti + Pesto; Rice + Pesto
Intervention type(s): Other; Other; Other; Other; Other; Other; Other; Other; Other
Intervention description(s): 50g available carbohydrate; 50g available carbohydrate; 50g available carbohydrate; 50g available carbohydrate; 50g available carbohydrate; 50g available carbohydrate; 50g available carbohydrate; 50g available carbohydrate; 50g available carbohydrate
Other intervention name(s): Glucose Monohydrate; Glucose Monohydrate; Glucose Monohydrate; white rice; white rice + tomato sauce; white rice + pesto
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Basic Science
Keywords: glycemic index