The Acute Effects of Interesterification of Commercially Used Fats on Postprandial Lipaemia and Satiety

The Acute Effects of Interesterification of Commercially Used Fats on Postprandial Lipaemia and Satiety: a Randomised Controlled Trial. The INTER-FAT Study

The purpose of this study is to investigate whether there are differences in postprandial metabolic indices following interesterified fats used in commercial spreads versus the corresponding un-interesterified blend.

Aim: The current study aims to investigate the acute effects of commercially relevant interesterified 'hardstock' versus the corresponding un-interesterified blend on postprandial lipaemia, glycaemia, insulinaemia and gut hormone responses. Due to the previously observed differences in gut hormones following interesterified palm oil and un-interesterified palm oil by our group, we will also explore acute effects of these fats on satiety and rates of gastric emptying.

Hypothesis: Interesterification of a palm kernel and palm stearin fat blend, to produce a fat with a higher proportion of palmitic acid in the middle position of the TAG (but the same fatty acid composition), will alter postprandial lipid and glucose metabolism. It is also hypothesised that differences in rates of absorption between the test fats will influence gut hormone responses and feelings of satiety.

Subjects: Participants will include 10 healthy male volunteers. In order to determine the 'typical' response to the test fats, subjects must not be affected by metabolic syndrome in any way (obesity, dyslipidemia, insulin resistance or hypertension), they must be non-smokers (since smoking influences postprandial lipaemia), and be aged between the ages of 18 and 45 years (since above this age metabolic changes may take place that may affect the way that the body digests and metabolises lipids). Male volunteers have been selected as they elicit a higher postprandial lipaemic response to a given fat load and therefore are more sensitive to dietary manipulation.

Power calculation: A sample size of 10 has 80% power to detect a difference between means of 112.74 units in area under the curve in plasma TAG with a significance level (alpha) of 0.05 (two-tailed).

Expected value:

The study will provide novel information on the acute effects of commercially relevant spreads on postprandial lipaemia and satiety. It will also explore possible mechanisms for the predicted reduced lipaemia following the interesterified fat from measurements of gastric emptying.

Inclusion Criteria:

1. Age: 18-45
2. Male
3. Healthy (free of diagnosed diseases listed in exclusion criteria)
4. Able to understand the information sheet and willing to comply with study protocol
5. Able to give informed consent

Exclusion criteria:

1. Medical history of myocardial infarction, angina, thrombosis, stroke, cancer, liver or bowel disease or diabetes
2. Body mass index < 20 kg/m2 or > 35 kg/m2
3. Plasma cholesterol ≥7.5 mmol/L
4. Plasma triacylglycerol > 3 mmol/L
5. Plasma glucose > 7 mmol/L
6. Blood pressure ≥160/100 mmHg
7. Current use of antihypertensive or lipid lowering medications
8. Alcohol intake exceeding a moderate intake (> 28 units per week)
9. Current cigarette smoker
10. ≥ 20% 10-year risk of cardiovascular disease as calculated using risk calculator
11. Ingestion of paracetamol in the preceding 24 hrs to study days