Trans Fat

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