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Cardiovascular Risk Factors Affected By Diet

A high fat diet has a beneficial effect on postprandial glucose and insulin over time but, it is associated with higher postprandial concentrations of triacylglycerols and non-esterified fatty acids, report researchers.

A high glycaemic index diet also appears to increase postprandial insulin resistance over time, however, say researchers from the Hammersmith Hospital, London, England.

Postprandial concentrations of glucose, insulin and triacylglycerols correlated with risk for coronary heart disease, they point out. Carbohydrates affected many metabolites that could affect cardiovascular risk factors.

The researchers carried out a randomised crossover study which looked at the effect of carbohydrates on daytime profiles of insulin, glucose, non-esterified fatty acids and triacylglycerols in 17 middle-aged men with one or more cardiac risk factors.

The researchers examined the acute (day 1) and medium-term (day 24) effects of four different diets:

1. High-fat: half fat and at least 34% monounsaturated fatty acids;
2. Low glycaemic index: high in carbohydrate as well as low glycaemic index;
3. High-sucrose: high carbohydrate increase of 90 grams sucrose per day;
4. High glycaemic index: high in both carbohydrate and glycaemic index.

Daytime profiles of lipid and carbohydrate metabolism were completed at breakfast, lunch and late afternoon on days 1 and 24.

There was no change from day 1 or, on day 24, between diets in fasting glucose, lipids or homeostatic assessment model.

When compared with the three high-carbohydrate diets, the high fat diet was associated with lower postprandial insulin and glucose but higher postprandial triacylglycerols and non-esterified fatty acids.

There was a significant increase with the high sucrose diet between days 1 and 24 in triacylglycerol concentration at 15.00 hours.

Postprandial homeostatic assessment mode median changes from day 1 to 24 were falls of 61% for the high fat diet, 43% for the low glycaemic index diet and 20% for the high sucrose diet.

The high glycaemic index diet was significantly different from these, with a rise of 31%.

Although patients were advised to maintain an identical energy intake with the different diets, there was significant weight loss on the low glycaemic index diet compared with weight gain on the high sucrose diet.
British Journal of Nutrition 2003;89:2:207-218. "A randomised four-intervention crossover study investigating the effect of carbohydrates on daytime profiles of insulin, glucose, non-esterified fatty acids and triacylglycerols in middle-aged men."

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