A new study published this week shows there has been a big drop in levels of trans-fatty acids in the US bloodstream. From 2000 to 2009 it fell by 58%. This is the first time researchers from the US Centers from Disease Control and Prevention (CDC) have been able to measure trans-fats in human blood. They write about their findings in a letter to the Editor of JAMA.

Trans-fatty acids (TFAs) are a group of fats that, unlike other dietary fats, are not essential to health. In the human diet they come from two sources: synthetic and natural.

The synthetic sources include products where manufacturers have hydrogenated vegetable oils to make them solid at room temperature and thereby increase their shelf life. TFAs are also present in small quantitites in meat and milk products since grazing animals produce them naturally.

Studies suggest that consuming high levels of TFAs is linked to cardiovascular disease, partly because they increase levels of “bad” cholesterol (LDL), and that changing to a diet low in TFAs may lower LDL cholesterol and thus reduce the associated health risks.

In 2003, the Food and Drug Administration (FDA) introduced new regulations, which came into force in 2006, requiring food and some dietary supplement manufacturers to show levels of TFAs in their products.

So the blood levels measured in the study cover the period before and after consumers could see the amount of TFAs in the products they were buying.

During the same period several parts of the country brought in new laws limiting TFAs in restaurant food and cooking and promoted public awareness campaigns about the health risks of TFAs.

Dr Christopher Portier, director of CDC′s National Center for Environmental Health, told the press:

“Findings from the CDC study demonstrate the effectiveness of these efforts in reducing blood TFAs and highlight that further reductions in the levels of trans fats must remain an important public health goal.”

The study is based on data taken from the National Health and Nutrition Examination Survey (NHANES) and covers a representative sample of white adults only (age 20 and older).

Portier said CDC studies looking at trends in other ethnic and racial groups as well as children and adolescents are already under way.

To provide a reasonable representation of TFAs in blood, the researchers examined four major TFAs: elaidic acid, linoelaidic acid, palmitelaidic acid, and vaccenic acid, in 229 fasting adults from the 2000 survey and 292 from the 2009 survey.

They found that all four TFAs reduced significantly over the period: elaidic acid by 63%, linoelaidic acid by 49%, palmitelaidic acid by 49%, and vaccenic acid by 56%. The overall decrease was 58%.

You can reduce your consumption of TFAs by:

  • Reading the trans-fats listing on the nutrition facts label of food products and choosing the brand with the lowest amount, or even better, with no trans-fats at all.
  • Replacing margarines containing trans-fats with unsaturated vegetable oil.
  • If you use margarine, rather than a stick one, use a soft-spread one: read the label to double check that it contains less trans-fats (preferably none at all).

The study is part of CDC′s larger National Biomonitoring program. The program currently measures over 450 environmental chemicals and nutritional indicators in people.

Written by Catharine Paddock PhD