The study is a randomized, cross-over, double blind, controlled trial in which study participants will visit the research facility on two occasions under fasting conditions with a minimum of 1 week between visits. During each visit, participants will receive a carbohydrate rich test-meal with Kori-tofu (protein) or whey protein. The two meals will be given in randomized order and blood will be collected via a catheter before and up to 3 hours after consumption of the test-meal. Study participants will also wear continuous glucose meters during the trial. They will receive a standardized evening meal prior to each study day and are asked not to drink alcohol or perform heavy exercise the day before. After each test day participants are offered a meal.

There are several types of tofu, an example of a specific type of tofu is called Kori-tofu. Kori-tofu literally means frozen tofu. The production process of Kori-tofu leads to the formation of a higher high molecular weight fraction (HMF) content of the soy proteins. Several clinical studies describe the effects of Kofi-tofu on health. In this study, the aim is to investigate whether Kori-tofu protein affects postprandial blood glucose concentrations in participants with an impaired glucose tolerance.

The primary objective is to investigate whether Kori-tofu protein affects postprandial blood glucose concentrations, when administered as a part of an ordinary high carbohydrate meal. The secondary objective is to investigate whether Kori-tofu protein affects postprandial insulin concentrations.

The study is a randomized, cross-over, double blind, controlled trial in which study participants will visit the research facility on two occasions under fasting conditions. Subjects will receive two different carbohydrate-rich meals, either with added Kori-tofu or whey protein, with a washout period of one week. Blood will be collected via a catheter before and up-to 3 hours after consumption of the test-meal.

Inclusion Criteria:

• BMI >25 kg/m2

• Having veins suitable for blood sampling via a catheter

• Having one or more of the following criteria:

  • HbA1c> 6%
  • fasting glucose >6.1mmol/L
  • two-hour glucose levels >7.8 mmol/L on the 75-g oral glucose tolerance test.

Exclusion Criteria:

• History of gastro-intestinal surgery or having (serious) gastro-intestinal complaints
• History of liver dysfunction (cirrhosis, hepatitis) or liver surgery
• Kidney dysfunction (self-reported)
• Use of medication/supplements that may influence the study results, such as med-icines known to interfere with glucose homeostasis (judged by our study doctor)
• Anaemia (Hb values <7.5 for women and <8.5 for men)
• Reported slimming, medically prescribed or other extreme diets
• Reported weight loss or weight gain of > 5 kg in the month prior to pre-study screening
• Not willing to give up blood donation during the study
• Current smokers
• Alcohol intake ≥4 glasses of alcoholic beverages per day
• Abuse of illicit drugs
• Food allergies for products that we use in the study
• Participation in another clinical trial at the same time
• Being an employee of the Food, Health & Consumer Research group of Wageningen Food & Biobased Research.