Trans Fat

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Trans Fat
Lab to Label
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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.

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What is a Trans Fat?
Oleic (9-cis-C181) mp 13-14C Elaidic
(9-trans-C181) mp 44-45C
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Where Does Trans Fat Come From?

• Chemical Hydrogenation of Vegetable Oils (may be
  gt50)
• Biochemical Hydrogenation by Rumen Bacteria (5
  or less)

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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

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Trans Added to Label

• Amended to Include Trans
• Required by Jan 2006

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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

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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

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How Are They Measured?

• Usually complex mixtures
• PHVO can have gt40 isomers of 18 Carbon FA
• More than 15 isomers of linoleic acids

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Hydrogenation Increases Complexity
C181
C182
C180
Salad Oil no hydrogenation
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Hydrogenation Increases Complexity
Margarine C18 region only
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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)

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Accurate Measurement ofTrans Fat in Foods

• Specialized GC Capillary Columns
• Very Long Columns (100 meters)
• Optimized Separation of Trans Fats

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Overview of Methodfor Measuring Fat
Critical step for trans fat
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Optimized Trans Analysis
Standard Separation (Could underestimate Trans by
up to 25)
Optimized Separation
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Optimized Trans Fat Separation

• 100 Meter Capillary Column
• Specialized Stationary Phases
• Isothermal Column Temperature
• Split Injection

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US and Canadian Food Labels
List Separately
List Sum
Canada
US
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Trans Fat Label Requirements

• US
• Label trans fat gt0.5 g per serving
• If total fat lt 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 lt0.2 g per serving to
  list as zero
• Limited use of Not a significant source

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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

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Online Resources
Harvard School of Public Health Trans Fat
Report http//www.hsph.harvard.edu/reviews/transf
ats.html FDA Trans Fat Labeling QA
Sites http//www.cfsan.fda.gov/label.html http//w
ww.cfsan.fda.gov/dms/qatrans2.html