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Biomedical subjects

P A Crapo

Publications and source records attributed to P A Crapo.

At least 19 recordsLinked to original sources
PubMed1991

Current issues in fructose metabolism.

The ingestion of fructose, particularly in refined form, has significantly increased in the North American diet over the last two decades. The unique way in which fructose is metabolized has given rise to much research examining whether fructose is advantageous in appetite control, exercise endurance, and disease states such as diabetes. Overall, there is very little evidence that modest amounts of fructose have detrimental effects on carbohydrate and lipid metabolism in nondiabetic or NIDDM subjects or that its use is particularly advantageous compared to that of other sugars. However, fructose can cause insulin and triglyceride levels to rise dramatically, and hence be potentially harmful, in a subgroup of NIDDM subjects who have concomitant pronounced hypertriglyceridemia. Large doses of fructose should also be avoided by subjects with gout because of the hyperuricemia which may result. No evidence exists that fructose has any clear advantages over glucose in regard to exercise endurance. Similarly there is no conclusive evidence that physiologic amounts of dietary fructose exacerbate copper deficiency or aid in weight control.

Animals↗
PubMed1990

Long-term effects of dietary fructose on carbohydrate metabolism in non-insulin-dependent diabetes mellitus.

The effect of dietary fructose on glycemic control in subjects with diabetes mellitus is controversial. Therefore our aim was to conduct a long-term study to examine the effects of dietary fructose on glucose tolerance and insulin sensitivity and to delineate the mechanisms for the effects observed. Six subjects with non-insulin-dependent diabetes mellitus (NIDDM) who were being treated by diet alone consumed 13% of their calories as fructose incorporated into mixed meals in place of sucrose for 3 months as inpatients on a metabolic ward. The following parameters were measured: (1) weekly fasting plasma-glucose concentrations, (2) postprandial serum glucose and insulin levels after four sugar tolerance tests, (3) basal hepatic glucose production, and (4) hepatic and whole-body insulin sensitivity determined during a hyperinsulinemic, euglycemic clamp. When modest amounts of fructose were substituted for sucrose in the diet for 3 months, basal hepatic glucose output remained unchanged (12.84 +/- 1.83 nmol/kg/min v 12.51 +/- 2.00 nmol/kg/min) as did hepatic insulin sensitivity (92% +/- 4% v 93% +/- 4% suppression) and peripheral glucose disposal (22.52 +/- 4.56 nmol/kg/min v 25.80 +/- 9.45 nmol/kg/min) to a 860 pmol/m2/min insulin infusion at euglycemia (4.8 mmol/L). Fructose feeding also did not alter fasting plasma-glucose concentrations or postprandial plasma glucose and insulin responses to oral glucose or fructose loads or to mixed meals containing either sucrose or fructose. In conclusion, substitution of physiologic amounts of sucrose by fructose for prolonged periods is unlikely to have adverse effects on glucose metabolism in diabetic subjects who are being treated with diet alone.

Adult↗
PubMed1989

Lipid metabolism in non-insulin-dependent diabetes: effects of long-term treatment with fructose-supplemented mixed meals.

Using fructose in the diabetic diet remains controversial primarily because of the potential for adverse effects on serum lipids. Therefore, lipid metabolism was evaluated in five NIDDM subjects (as inpatients) for 3 mo before and after ingestion of mixed meals containing 13% of calories as fructose. Triglyceride (TG) transport in very-low-density lipoproteins (VLDL) was assessed by multicompartmental analysis of VLDL-TG specific activity after injection of 3H-2-glycerol. There were no deleterious changes in lipid metabolism after fructose supplementation. The fructose diet produced no changes in serial free fatty acids (from 0.39 +/- 0.04 to 0.51 to 0.12 mmol/L), total cholesterol (from 5.43 +/- 0.52 to 5.53 +/- 0.57 mmol/L), high-density lipoproteins (from 0.91 +/- 0.08 to 0.93 +/- 0.08 mmol/L), low-density lipoproteins (from 3.10 +/- 0.52 to 2.92 +/- 0.47 mmol/L), VLDL-TG production (from 2.11 +/- 0.36 to 2.07 +/- 0.30 mmol/h), and fractional catabolic rate (from 0.186 +/- 0.014 to 0.196 +/- 0.03/h). Physiologic amounts of fructose are unlikely to have adverse effects on lipid metabolism when consumed by these diabetic subjects in place of sucrose in mixed meals for a prolonged period.

Blood Glucose↗
PubMed1988

Postprandial metabolic responses to the influence of food form.

To determine whether differences in the metabolic response to two common starches could be eliminated by altering the physical form of food, 12 normal and 6 noninsulin-dependent diabetic (NIDDM) subjects were studied after consumption of test loads of whole and blended rice and potato. In normal and NIDDM subjects the lower postprandial glycemia and insulinemia of whole rice was eliminated and became similar to that of whole potato, which was unaffected by blending. The glucagon responses were unchanged and similar in both groups under all study conditions. In both normal and NIDDM subjects the glucose and insulin response to a particular starch is not a stable feature dependent on the unique characteristics of the starch molecule but is affected by food processing and the form in which it is presented to the gastrointestinal tract.

Adult↗
PubMed1988

Use of alternative sweeteners in diabetic diet.

Alternative sweeteners are widely advocated and used. However, there is insufficient scientific information to determine whether alternative sweeteners aer of value in the management of diabetes, either in improving dietary adherence or in contributing to the achievement or maintenance of a lower body weight. Each of the available sweeteners has advantages and disadvantages; no one is preferred. Recommendations about alternative-sweetener use should be tailored to the specific dietary and life-style patterns of the individual.

Diet, Diabetic↗
PubMed1984

The metabolic effects of 2-week fructose feeding in normal subjects.

Be studied the metabolic effects of 2 wk of fructose feeding as the sweetener in the diet of 11 normal individuals. The data demonstrated 1) no adverse effects of the fructose containing diet on triglyceride, pyruvate, lactate, or uric acid metabolism; 2) no apparent adaptation in the metabolism of fructose; 3) markedly flattened postprandial serum glucose and insulin responses to pure fructose; and 4) a modest decline in postprandial glucose and insulin levels after ingestion of standard fructose containing mixed meals as compared to sucrose-containing mixed meals.

Adult↗
PubMed1982

Comparison of the metabolic responses to fructose and sucrose sweetened foods.

We studied the acute effects of oral ingestion of fructose and sucrose sweetened cakes and ice creams on postprandial serum glucose and insulin responses in 10 normal subjects, six subjects with impaired glucose tolerance, and 10 noninsulin-dependent diabetic subjects. The data demonstrate that: 1) ingestion of fructose cakes and ice creams resulted in lower serum glucose and insulin responses than did the sucrose cakes and ice creams in all study groups; 2) when comparing cakes to ice creams, the serum glucose and insulin responses after ice cream ingestion were lower than responses after cake ingestion. In conclusion, when fructose is incorporated as a sweetener in a complex food product, it is associated with significantly lower serum glucose and insulin responses as compared to comparable sucrose sweetened foods.

Adult↗
PubMed1981

Hormonal and substrate responses to a standard meal in normal and hypertriglyceridemic subjects.

Postprandial plasma insulin, glucose, growth hormone, cortisol and free fatty acid responses to a standard mixed meal were determined and compared to fasting plasma triglyceride levels in normal and hypertriglyceridemic subjects. The hypertriglyceridemic subjects had significantly higher postprandial plasma insulin levels than did normals, but no significant differences were seen between the two groups to any of the other variables. Postprandial plasma insulin levels were highly correlated to fasting plasma triglyceride levels, but there was no significant correlation between any of the other variables and fasting plasma triglyceride levels.

Adult↗
PubMed1981

Comparison of serum glucose, insulin, and glucagon responses to different types of complex carbohydrate in noninsulin-dependent diabetic patients.

We have studied the acute effects of oral ingestion of dextrose, rice, potato, corn, and bread on postprandial serum glucose, insulin, and glucagon responses in 20 diabetic subjects with nonketotic, noninsulin requiring fasting hyperglycemia. The carbohydrate loads were all calculated to contain 50 g of glucose. The data demonstrate that 1) dextrose and potato elicited similar postprandial serum glucose responses whereas rice and corn elicited lower responses, with bread intermediate; 2) postprandial insulin responses were relatively flat but rice ingestion led to significantly lower insulin responses than did potato; 3) urinary glucose excretion during the 3 h after carbohydrate ingestion was greatest following dextrose and least after rice and corn. In conclusion, there is a range in the magnitude of postprandial hyperglycemia after ingestion of different complex carbohydrates in diabetic patients with fasting hyperglycemia and emphasis on the use of the less hyperglycemic starches could be of therapeutic value in controlling hyperglycemia.

Adult↗
PubMed1980

Postprandial hormonal responses to different types of complex carbohydrate in individuals with impaired glucose tolerance.

We have studied the effects of dextrose, rice, potato, corn, and bread on postprandial plasma glucose, insulin and glucagon responses in 11 subjects with impaired glucose tolerance. All carbohydrate loads were calculated to contain 50 g of glucose. The data demonstrate that 1) dextrose and potato elicited similar plasma glucose responses whereas rice, and bread elicited lower responses with corn intermediate; 2) dextrose and potato elicited similar plasma insulin responses whereas rice gave lower responses, with bread and corn intermediate; 3) all of the carbohydrate loads suppressed plasma glucagon with dextrose causing the greatest suppression. In conclusion, there is a range of plasma glucose, insulin, and glucagon responses to different complex carbohydrates in subjects with impaired glucose tolerance and the differences in plasma glucose responses may be of therapeutic value in controlling hyperglycemia.

Adult↗
PubMed1977

Postprandial plasma-glucose and -insulin responses to different complex carbohydrates.

We have studied the effects of dextrose, rice, potato, corn, and bread on postprandial plasma glucose and insulin responses in 16 subjects. All carbohydrate loads were calculated to contain 50 gm. of glucose. The data demonstrate (1) that dextrose and potato elicited similar plasma glucose responses whereas rice, corn, and bread elicited lower responses; (2) similarly, dextrose and potato elicited similar and greater plasma insulin responses than rice and corn, with the response to bread being intermediate; (3) when the study group was divided in half, on the basis of each subject's one-hour plasma glucose response to dextrose, the differences in the plasma glucose and insulin responses were greater in the subjects with the highest glucose response to dextrose than in the low responders. In conclusion, there is a range of plasma-glucose and insulin responses to different complex carbohydrates, with rice and corn producing the lowest response curves. Furthermore, these differences are accentuated in patients with reduced glucose tolerance.

Blood Glucose↗
PubMed1976

Plasma glucose and insulin responses to orally administered simple and complex carbohydrates.

We have studied the effects of glucose, sucrose, and various starches on postprandial plasma glucose and insulin responses in 19 subjects. All carbohydrate loads were calculated to contain 50 gm. of glucose, and the response to each carbohydrate was tested twice: when given alone in a drink or when given in combination with other nutrients as a meal. The data demonstrate: (1) Glucose and sucrose elicited similar plasma glucose response curves, but sucrose elicited a somewhat greater (20 per cent) plasma insulin response. (2) Raw starch ingestion resulted in a 44 per cent lower glucose response and a 35-65 per cent lower insulin response than did either glucose or sucrose ingestion. (3) When carbohydrate was given as a meal the plasma glucose responses were 40-60 per cent lower than when the same carbohydrate was given as a drink, while the insulin responses were generally similar, and (4) when different cooked starches were compared, the plasma glucose and insulin responses to rice were significantly lower (50 per cent) than to potato. In conclusion, the size of the carbohydrate molecule appears to influence the postprandial glucose and insulin responses such that more complex carbohydrates (starches) elicit lower responses. This effect may be related to differences in digestion rather than to differences in absorption.

Adult↗
PubMed1975

Metabolic effects of increased caloric intake in man.

In order to determine if increased caloric intake could be responsible for the insulin resistance and elevated plasma glucose, insulin, and triglyceride levels commonly associated with obesity, hypercaloric diets were fed for 3 wk to eight normal subjects, and the metabolic consequences of this diet were assessed before significant weight gain had occurred. One wk of increased caloric intake led to statistically significant increases in fasting plasma insulin (22 per cent), glucose (5 per cent), and triglyceride (30 per cent) levels, as well as an increased insulin response (20 per cent) to oral glucose. Since the average weight gain during this period was only 1.6 kg, the observed changes appear to be secondary to increased caloric consumption, not obesity. Most of these changes returned toward baseline values during the succeeding 2 wk of increased caloric intake, but statistically significant elevations of fasting plasma glucose (10 per cent), insulin (8 per cent) and cholesterol (15 per cent) levels were still seen at the end of the hypercaloric dietary period. On the other hand, insulin resistance, as estimated by direct measurement of insulin responsiveness, did not change as a result of 3 wk of increased caloric intake. These results indicate that acute increases in caloric intake can lead to elevated plasma glucose, insulin, cholesterol, and triglyceride levels. These changes occurred before significant weight gain had taken place, and raised the possibility that at least some of the abnormalities of carbohydrate and lipid metabolism attributed to obesity may be due to increased caloric intake. However, this conclusion would not seem to apply to the insulin resistance associated with obesity, as 3 wk of increased caloric intake did not produce any change in the responsiveness of these subjects to insulin's action.

Adult↗