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Trans Fat

Trans fats are unsaturated fatty acids that have been chemically modified to improve their stability and shelf life. They are primarily produced through the hydrogenation of vegetable oils and can be found in margarine, fried foods, and baked goods. Trans fats are linked to increased LDL cholesterol levels and can lead to serious health issues, including premature deaths. The labeling of trans fats has been mandated in many regions to inform consumers. This guide explores trans fat composition, health impacts, sources in food, and current regulatory requirements.

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Trans Fat

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  1. Trans Fat Lab to Label

  2. What is trans fat? • Chemically: Geometric isomers of the natural cis form of unsaturated fatty acids • Physically: Fatty acids modified to have a higher melting point by changing their configuration from bent to straight.

  3. What is a Trans Fat? Oleic (9-cis-C18:1) mp: 13-14C Elaidic (9-trans-C18:1) mp: 44-45C

  4. Where Does Trans Fat Come From? • Chemical Hydrogenation of Vegetable Oils (may be >50%) • Biochemical Hydrogenation by Rumen Bacteria (5% or less)

  5. Some Food Labeling History • Nutrition Labeling & Education Act 1990 • Major Change in Fat Definition • New Fat Methodologies Required • Only “cis” fats included in unsaturates • Call for Trans Fat Labeling • Decision Delayed Pending Better Data

  6. Trans Added to Label • Amended to Include Trans • Required by Jan 2006

  7. Why Trans Fat? • Trans Fat Raises LDL Cholesterol/Lowers HDL • Trans Fat Increases Plasma TGs • May Be Stronger CHD Factor than Saturated Fat • Up to 100,000 Premature Deaths/yr in US • Average US Consumer Gets 2% of Calories from Trans Fat

  8. What Foods Contain Trans Fat? • Margarines (Hard varieties are higher) • Shortenings and Frying Fats • Fried Foods • Beef and Dairy Fats • Bakery Products But . . . . Changing Rapidly

  9. How Are They Measured? • Usually complex mixtures • PHVO can have >40 isomers of 18 Carbon FA • More than 15 isomers of linoleic acids

  10. Hydrogenation Increases Complexity C18:1 C18:2 C18:0 Salad Oil – no hydrogenation

  11. Trans C18:1 C18:1 C18:2 Hydrogenation Increases Complexity Margarine C18 region only

  12. How Are They Measured? • FTIR for Process Control of Fats and Oils (high levels, not for complex foods, specific) • HRGC for Products and Ingredients (low levels, complex foods, not specific) • Ag+ Chromatography/GC (Not practical at present, but may be useful in future)

  13. Accurate Measurement ofTrans Fat in Foods • Specialized GC Capillary Columns • Very Long Columns (100 meters) • Optimized Separation of Trans Fats

  14. Crude Extract Saponify with KOH Esterify with Acid/MeOH Separate and Measure by GC Overview of Methodfor Measuring Fat Critical step for trans fat

  15. Optimized Trans Analysis Standard Separation (Could underestimate Trans by up to 25%) Optimized Separation

  16. Optimized Trans Fat Separation • 100 Meter Capillary Column • Specialized Stationary Phases • Isothermal Column Temperature • Split Injection

  17. US and Canadian Food Labels List Separately List Sum Canada US

  18. Trans Fat Label Requirements US • Label trans fat >0.5 g per serving • If total fat < 0.5 g per serving, not required, but “Not a significant source of trans fat” No fat or cholesterol claims allowed • No nutrient content claims for trans fat Canada • Both sat fat and trans fat <0.2 g per serving to list as “zero” • Limited use of “Not a significant source”

  19. Future • Other Label Changes Being Studied • May Add a %DV for Trans Fat • May Allow Nutrient Content Claims for Trans Fat • Trans Fats Rapidly Disappearing from Food Products

  20. Online Resources Harvard School of Public Health Trans Fat Report: http://www.hsph.harvard.edu/reviews/transfats.html FDA Trans Fat Labeling Q&A Sites http://www.cfsan.fda.gov/label.html http://www.cfsan.fda.gov/~dms/qatrans2.html

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