Do carbohydrates promote hypertension?

Several earlier studies indicate an association between plasma insulin level and blood pressure independent of weight. A short review summarizes evidences showing: (a) the association between a high carbohydrate content of diet and hyperinsulinemia; (b) effect of insulin on renal reabsorbation of sodium; and (c) effects of carbohydrate intake on sympathetic activity and blood pressure. A pilot study examined the effect of a glycoside-hydrolase inhibitor (BAY g 5421) on blood pressure, fasting blood glucose, fasting plasma insulin and 100 g peroral sucrose test in six obese middle-aged men with borderline hypertension. The protocol included three periods of four weeks each. During the second and third period placebo and BAY g 5421 (100 mg three times per day) were given in a randomized, double-blind fashion. At the end of each period blood pressure was recorded during 30 minutes of rest in a supine position. The subjects also orally received 100 g sucrose as a 50 per cent solution dissolved in water. BAY g 5421 caused a significant decrease of plasma insulin after a 100 g sucrose tolerance test as compared to placebo. Blood pressure after four weeks of treatment with placebo was 135 +/- 5.7 systolic and 92 +/- 6.6 diastolic (mmHg, mean +/-s.d.) and after four weeks of treatment with BAY g 5421 was not significantly different. There was no change in weight. The question whether carbohydrates promote hypertension has to be further investigated.