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Trans Fats – the UGLY Fat
Presented by:
Dr. Christine Simpson
CHIP Alumni - June 20, 2006
Walter C. Willett, MD
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“Only one type of dietary fat is worse for you than
saturated fat---the increasingly common trans fat.”
“...thirty thousand or more premature heart disease
deaths each year” are “due to trans fats in our food
supply.”
Chairman of Dept of Nutrition,
Harvard School of Public Health &
Professor of Medicine, Harvard Medical School
Eat, Drink, and Be Healthy, pp 71, 73
What are fatty acids?
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Chains of carbon atoms with hydrogen
atoms attached
The important way fatty acids differ:
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degree of saturation = how many hydrogen
atoms the carbon chains carry
saturated fatty acids
 monounsaturated fatty acids
 polyunsaturated fatty acids
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Saturated fatty acid
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Fully loaded with hydrogen atoms
Only single bonds between carbon atoms
Straight molecule, stiff, pack together
Examples:
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Animal-based fats (meat and dairy)
Solid plant-based fats, such as coconuts,
palm fats, etc.
In general, saturated fats tend to increase
the risk of heart disease (raise LDL levels,
but also raise HDL levels)
Monounsaturated fatty acid
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One pair of hydrogen atoms missing
One double bond between carbons
Hydrogen on same side of double bond = cis
configuration
Bent molecule, flexible, not pack together
Examples:
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Olive oil
Canola oil
Avocado
In general, monounsaturated fats tend to
lower the risk of heart disease when
consumed in moderate amounts.
Polyunsaturated fatty acid
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Two or more pairs of hydrogen atoms missing
Two or more double bonds between carbons
Hydrogen on same side of double bond = cis
configuration
Bent molecule, more flexible, not pack together
Examples:
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(these include the omega-3’s and 6’s)
Corn oil
Sunflower oil
Soybean oil
Canola oil
Flaxseed oil
Hemp seed oil
In general, polyunsaturated fats tend to lower the risk of
heart disease when consumed in moderate amounts.
Process of hydrogenation
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Oils are reacted under pressure with hydrogen
High temperatures: 248 - 410º F
Metal catalyst: nickel, platinum
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‘Raney’s Nickel: 50% nickel, 50% aluminum
6 - 8 hours
Creates man-made “saturated fats”
Introduced in 1930s: makes margarines &
shortenings as cheaper substitutes for butter,
lard, etc.
Partial hydrogenation
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Some of the double bonds are lost 
saturated
Some of the remaining unsaturated double
bonds: cis  trans configuration
Trans configuration = hydrogen atoms on
opposite sides of carbon chain
Cis vs trans
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Trans = “unnatural” position
Trans unsaturated fatty acids behave like
saturated fatty acids  straight, stiff, pack
together
What is a Trans fatty acid/Trans fat
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Trans fatty acid: unsaturated fatty acid in
which at least one of the double bonds
has been changed from the cis to the
trans configuration
Trans fat: fat in which most of the fatty
acids are trans fatty acids
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example: vegetable shortening (Crisco)
Trans fats: man-made, “artificial” fats
Where are trans fats found?
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Low levels naturally occur in meat and
milk (bacterial action in the gut)
Low levels in canola and soybean oils due
to the commercial refinement
The rest comes from partial hydrogenation
Results of partial hydrogenation
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From the food manufacturers point of view:
GOOD
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more resistant to spoilage
easier to ship and store
longer shelf life
fat is more solid
changes in textures of foods
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liquid oils become spreadable margarines
pie crusts flakier
Results of partial hydrogenation
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From the health professionals point of
view: NOT GOOD
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unsaturated fatty acids act like saturated
fatty acids in the body because of the trans
configuration at the double bonds
Evidence that it is actually worse than
saturated fats
Health effects of trans fats
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Increases LDL
Decreases HDL
Increases Lipoprotein (a) – Lpa
Increases risk of preecclampsia in pregnancy
Makes platelets stickier  increases risk of forming clots
May promote insulin resistance
Epidemiological studies:
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Increased risk of Alzheimer’s
Increased risk of Diabetes Type 2
Process of hydrogenation:
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destroys vitamin E, carotenoids
destroys essential fatty acids
adds traces of nickel and/or aluminum to the human body which may
cause toxicity at high levels
Health effects of trans fats cont’d:
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Intake associated with increased risk of
heart disease
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Harvard Nurses Health study
higher trans fat intake (3% of total calories) related
to higher incidence of nonfatal heart attacks and
death from coronary heart disease
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53% greater risk than those with lowest trans fat
intake (1% of total calories)
Hu, FB, Stampfer MJ, Manson JE, et al. Dietary fat intake and the risk of
coronary heart disease in women. N Eng J Med 1997;337:1491-1499.
Health effects of trans fats cont’d:
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Authors conclude: replacement of the 2% of
calories from trans fat with calories from
unhydrogenated, unsaturated fats would reduce
heart disease risk by 53%
Practical application:
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2000 calories  .02 = 40 calories
1 gram of fat yields 9 calories
40 calories  9 = 4.4 grams of trans fat
Estimated 53% reduction in heart disease if
eliminated!!!
Where are trans fats found in food?
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Many margarines
Commercially fried foods
Bakery products made with margarine,
shortening or partially hydrogenated oil
Crackers, cookies, donuts, pastries, muffins,
croissants, snack foods
** the trans fat content of these foods can be as
high as 45% of the total fat!!
Dietary recommendations
Food & Nutrition Board, National Institute of Medicine
Dietary Reference Intakes for Energy, Carbohydrates,
Fiber, Fat, Protein and Amino Acids (2002)
“Trans fatty acids are not essential and provide no known
benefit to human health. Therefore, no AI (Adequate
Intake) or RDA (Recommended Dietary Allowance) is set.
Similar to saturated fatty acids, there is a positive linear
trend between trans fatty acid intake and LDL cholesterol
concentration, and therefore increased risk of CHD. An UTL
(Upper Tolerable Limit) is not set for trans fatty acids
because any incremental increase in trans fatty acid intake
increases CHD risk.…it is recommended that trans fatty acid
consumption be as low as possible while consuming a
nutritionally adequate diet.”
In Canada…..
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Average consumption of trans fats is 10
grams per day, the highest in the world
Consumption of just 5 grams per day
increases the risk of heart disease by
almost 20 %.
Trans fat on food labels
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Ingredient list: trans fat is present if the list includes
“partially hydrogenated oil,” or “shortening,” or
“margarine”
Definition of “fat-free” = less than 0.5 grams of fat
per serving (and no added fat or oil); synonyms include
“zero-fat,” “no-fat,” and “nonfat”
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hypothetical example: one serving (2 Tbs) contains 0.4 g trans
fat
package says “trans free”
you eat 6 servings (3/4 cup) and get 2.4 g trans fat
certainly not trans fat-free!
Up until recently, nutrition labeling
of foods has been voluntary!
As of December 12, 2005:
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Legislation in Canada (the first in the world)
made it mandatory that the total amount of
trans fat must be listed on the nutrition label.
Along with this is included:
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Total calories, total fat, saturated fat, cholesterol,
sodium, carbohydrate, fiber, sugars, protein, vitamin
A, vitamin C, calcium and iron
CAUTION!!!!
This legislation does not require fast
food outlets to label the nutrient
content of their products!!
To date, only one country (Denmark) has completely
banned the use of trans fats
Confusion for Consumers:
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Some fast foods sold in Canada contain levels of
trans fats that are among the highest in the
world
At the same time, some fast-food makers have
virtually eliminated trans fats, making them
world leaders
Levels of trans fats vary from country to country,
and from city to city, even on identical products
Examples:
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Toronto: kids’ meal of chicken nuggets
and French Fries at:
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KFC – 18.6 g of trans fats
Burger King – 13 g of trans fats
Vancouver: kids’ meals of chicken nuggets
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Macdonald’s - 1.8 g of trans fats
Wendy’s – 3.1 g of trans fats
How to Avoid them?
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Avoid commercially fried foods and high-fat
bakery goods
Read the labels on pre-packaged foods (look for
the trans fat content AND the term “partially
hydrogenated oil”).
Fry foods less, and when you do, use olive oil or
grape seed oil.
When you eat out, ask about the trans fat
content of foods on the menu.
Basic Principle:
Eat foods as grown,
simply prepared!!