The effects of changing dairy intake on trans and saturated fatty acid levels- results from a randomized controlled study

Jocelyne R Benatar,Ralph Ah Stewart

doi:10.1186/1475-2891-13-32

Abstract

BackgroundDairy food is an important natural source of saturated and trans fatty acids in the human diet. This study evaluates the effect of dietary advice to change dairy food intake on plasma fatty acid levels known to be present in milk in healthy volunteers.MethodsTwenty one samples of whole fat dairy milk were analyzed for fatty acids levels. Changes in levels of plasma phospholipid levels were evaluated in 180 healthy volunteers randomized to increase, not change or reduce dairy intake for one month. Fatty acids were measured by gas chromatography–mass spectrometry and levels are normalized to d-4 alanine.ResultsThe long chain fatty acids palmitic (13.4%), stearic (16.7%) and myristic (18.9%) acid were most common saturated fats in milk. Four trans fatty acids constituted 3.7% of the total milk fat content. Increased dairy food intake by 3.0 (± 1.2) serves/ day for 1 month was associated with small increases in plasma levels of myristic (+0.05, 95% confidence level-0.08 to 0.13, p = 0.07), pentadecanoic (+0.014, 95% confidence level -0.016 to 0.048, p = 0.02) and margaric acid (+0.02, -0.03 to 0.05, p = 0.03). There was no significant change in plasma levels of 4 saturated, 4 trans and 10 unsaturated fatty acids. Decreasing dairy food intake by 2.5 (± 1.2) serves per day was not associated with change in levels of any plasma fatty acid levels.ConclusionDietary advice to change dairy food has a minor effect on plasma fatty acid levels.Trial registrationACTRN12612000574842.

Highlights

Dairy food is an important natural source of saturated and trans fatty acids in the human diet
Studies suggest that increased plasma levels of trans [6] and saturated [7] fatty acids are associated with increased risk of cardiovascular disease
We evaluated the effects of dietary advice to increase, decrease or not change daily dairy food intake for one month on plasma fatty acid levels in a randomized clinical trial with180 healthy volunteers

Summary

Introduction

Dairy food is an important natural source of saturated and trans fatty acids in the human diet. Studies suggest that increased plasma levels of trans [6] and saturated [7] fatty acids are associated with increased risk of cardiovascular disease. Dairy food is a highly complex food comprised of constituents thought to be both harmful and beneficial for cardiovascular health It is the most abundant source of animal fat in the diet including saturated fats and ‘naturally occurring’ ruminant trans fatty acids (rTFA) [8]. It is rich in in long chain saturated fatty acids such as myristic and palmitic acids; thought to be harmful for cardiovascular health [9]. Dairy food contains unsaturated, short and medium chain saturated fatty acids thought to be beneficial for heart health [10,11]

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