Study of the Impact of Trans Fatty Acids From Dairy Products on Cardiovascular Risk Factors
Condition: Cardiovascular Disease
MeSH terms: Cardiovascular Diseases
Study type: Interventional

Summary: 
      The majority of trans fatty acids consumed by the general population is derived from products
      that have been formulated using significant amount of hydrogenated vegetable oil (the
      so-called industrial trans fat). Fat from ruminants also contains small amounts of trans
      fatty acid, which contribute, although to a smaller extent, to the total dietary intake of
      trans fatty acids in the general population. The negative impact of consuming industrial
      trans fat on health, particularly on cardiovascular disease, is being increasingly
      recognized. Based on data available to date, it is currently not possible to conclude if
      effects of ruminants and industrial trans fatty acid on cardiovascular risk are different.
      There is therefore an urgent need for a study that compares the impact of naturally occurring
      trans fatty acids such as those from dairy products and of trans fatty acids form industrial
      sources on cardiovascular risk factors as well as their mechanisms of action.

      The general objective of the study is to investigate the impact of naturally occurring trans
      fatty acids from dairy products (mainly vaccenic acid) on plasma cholesterol levels and other
      risk factors for cardiovascular disease.
    

Detailed description: 
      The proposed research will be undertaken as a double-blind randomized cross-over study
      according to a Latin Square design, with participants being subjected to 4 consecutive
      isocaloric diets in random order lasting 4 weeks each. No stratification is considered since
      the population recruited will be relatively homogeneous. The 4 experimental diets are: 1- a
      diet rich in ruminant TFA (8 g/day); 2- a diet moderately rich in ruminant TFA (4 g/day); 3-
      a diet rich in industrial TFA (8 g/d); 4- a control diet (minimal dietary TFA of industrial
      and ruminant sources). The source of ruminant TFA will come from butter and cream obtained
      after having modified the regimen of lactating cows in a fashion similar to the one used to
      increase the levels of conjugated linoleic acid (CLA) in milk fat. Hydrogenated margarine
      will be used as the main source of industrial TFA. Finally, a butter obtained from cows
      producing the lowest levels of ruminant fat will be used to formulate the control diet
      (minimal dietary TFA). All diets will be identical in terms of menus, calories and
      macronutrient composition with the exception of TFA sources and levels. Minor differences in
      the levels of total saturated, monounsaturated and polyunsaturated fatty acids will be
      matched across diets by adding various vegetable and animal oils. The macronutrient
      composition of each meal and thus of the entire day is very similar across all 4 diets. Based
      on a 2500 kcal/day regimen, an intake of TFA of 8 g/d and 4 g/d will represent 72 kcal/day
      and 36 kcal/day respectively (3% and 1.5% of energy intake). The 4 experimental diets will be
      formulated so that the percentage of daily calories from fat (36%), carbohydrates (50%) and
      proteins (14%) will meet most of the dietary recommendations of the American Heart
      Association and the NCEP for primary prevention of CVD, with the exception of SAT (slight
      excess) and fibers (slight deficit). The slight excess in SAT fat cannot be avoided since we
      are using butter as the primary source of ruminant TFA. The cholesterol content of the
      experimental diet will not exceed 300 mg/day.
    

Intervention name(s): Ruminant trans fats
Intervention type(s): Other
Intervention description(s): Consumption of the 4 experimental diets:
a diet rich in ruminant TFA (8 g/day);
a diet moderately rich in ruminant TFA (4 g/day);
a diet rich in industrial TFA (8 g/d);
a control diet (minimal dietary TFA of industrial and ruminant sources).
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Cardiovascular disease; Trans fatty acids; Ruminant; Blood lipids