In order to study the effect of protein, fat and dietary fiber on glycemic index(GI) of mixed food, the response of blood glucose and plasma insulin to nine diets with different components of food were tested by using glucose oxidase and radioimmunoassay. Glycemic index of 9 mixed foods show as follows, rice: 83.2 +/- 3.1, rice + stir fry pork: 72.0 +/- 14.0, rice + stir fry pork and celery: 57.1 +/- 11.2, rice + stir fry garlic sprout: 57.9 +/- 7.8, rice + stir fry garlic sprout and eggs: 62.8 +/- 16.7, steamed bread: 80.1 +/- 22.5, steamed bread + butter: 68.0 +/- 16.3, and steamed bread + beef: 49.4 +/- 22.8. Protein(P, beta 1 = -0.696, P < 0.01) and dietary fiber(Fi, beta 2 = -7.364, P < 0.01) can reduce the blood glucose response and were significantly related to GI. Fat also can inhibit the increment of blood glucose, but there is no significant relation with GI. When the co-ingestion of protein with carbohydrate, the serum insulin response increased greatly and the glycemic response reduced. The addition of fat can reduce the glycemic response without change in serum insulin. Dietary fiber can reduce the serum insulin response and inhibit the glycemic response.
Conclusion: Protein and dietary fiber of mixed food could markedly affect the glycemic index of foods and reduced the blood glucose response.