Trans Fats: Silent Killers

(Effect on Metabolism)

Refer to the Trans Fats Menu page or more articles on this subject

The Problem with Trans Fats

The Web MD website makes a troubling statement: “ Trans fats were developed during the backlash against saturated fat -- the artery-clogging animal fats found in butter, cream, and meats.” 4  This statement is troubling for two reasons:

  1. 1.Hydrogenated fats (now known as trans fats) were developed and marketed long before the campaign against saturated fats started in the 1950s.  In fact, history indicates that the libelous campaign against saturated animal fats started because consumers were not warming to the inexpensively produced hydrogenated fats, and the manufacturers needed to create a market.  Still, food manufacturers (especially fast food chains) were not keen on these new fats until they realized the fats had a longer shelf life than natural fats like butter and lard.

  2. 2.Animal fats are not “artery-clogging.”  Indeed, the studies cited to discredit animal fats actually used hydrogenated vegetable fats because it was believed that they were identical to animal fat, and were cheaper to obtain.  Yet the medical industry continues to support the claim that saturated animal fats are bad for you, as indicated by the Web MD quote cited above. (See my article, Saturated Fats: A Bad Rap for more on this)

The trans configuration (isomer) gives these chemically altered fats a different geometry than their natural cis counterpart.  The cis isomer has a kink at the double bond, causing the molecule to fold; the trans isomer is rigidly linear at the double bond, and does not fold.  This difference in geometry makes them biologically different, or non-bio-active, meaning they cannot be used by the body.  Yet they are chemically identical to the natural cis version from which they were made, and the body tries to use them. 

That is, they are absorbed from the digestive tract into the blood stream and carried to cells (as chylomicrons), just like their bio-active cis counterparts.  When the cells try to use them for metabolic purposes (such as energy production or creation of prostaglandins), problems ensue because their geometry is not right.  For example, they may bind to an enzyme and then inhibit it’s work.  They get incorporated into cell membranes where they can cause an undesirable stiffening of the membrane, as well as other metabolic problems, such as inhibiting the production of anti-inflammatory prostaglandins to fight inflammation.  This has been proposed as an underlying cause of insulin resistance (IR) and diabetes, and related metabolic problems under the moniker “Syndrome-X.”

If you increase your omega-3 consumption for health reasons, but continue to consume trans-omega-3 fats, your body is just as likely to try to use the bad trans molecule as the good cis version.  This is counter-productive.  If you normally consume any of the sources of trans fats listed below under “Food Sources of Trans Fats”, you are thwarting your progress with omega-3 supplementation.

Health Problems Attributed to Trans Fats

  1. Increases total cholesterol by 20-30%. 1

  2. Increases serum LDL (Low-density lipoprotein), the so-called “bad” cholesterol that transports cholesterol throughout the body.  Elevated levels of LDL have been linked to the formation of arterial plaque, which in turn has been implicated in heart disease and stroke. 2

  3. Decreases serum HDL (High-Density lipoprotein), the so-called “Good” cholesterol that picks up excess cholesterol and takes it back to your liver.  Decreased HDL is considered by many to be a more significant risk factor for heart disease and stroke, than elevated LDL.  Decreased HDL also often goes hand in hand with increased triglycerides (below). 2

  4. Increases serum triglycerides (VLDL, or very-low-densisty lipoprotein).  Elevated triglycerides is a strong risk factor for atherosclerosis (hardening and/or thickening of the artery walls), which increases the risk of stroke, heart attack and heart disease (CHD). 2

  5. Increases Lipoprotoein(a).  Less is known about Lp(a), a subclass of LDL, which, independent on other cholesterol levels, increases risk of heart disease. 2

  6. Increases inflammation.  Inflammation is the process used by the body to protect and heal itself from injury, both external and internal.  Trans fats appear to cause damage to the cells lining the blood vessels, inciting an inflammation response, thus playing a key role in the formation of arterial plaque and atherosclerosis. 2

  7. Increases CRP (C-Reactive Protein), a cell-signalling cytokine that is part of the inflammation response. 2

  8. Increased Obesity.  There is significant evidence that high consumption of trans fats leads to weight gain in animals and humans, despite similar caloric intake. 3  Trans fat consumption causes alterations in adipose cell size, cell number, lipid class, and fatty acid composition. 1

  9. Increased risk of type 2 diabetes (Insulin Resistance, or Syndrome-X). 

  10. [NOTE:  Type 1 diabetes is characterized by insufficient blood insulin.  Type 2 diabetes is characterized in the early stages by elevated blood insulin, and only changes to low blood insulin in later stages, when the pancreas wears out and can no longer produce sufficient insulin.]

  11. Trans fat consumption increases blood insulin levels in humans, in response to glucose load, increasing risk for diabetes. It also decreases the response of the red blood cell to insulin.  1  Barnard, et. al., reported in 1990 that trans fats have an adverse effect on insulin receptors and insulin binding. 3  Kuller reported in 1993 that frequent users of partially hydrogenated fats (as margarine) had higher insulin levels in response to glucose load. 3  Simopolous cited in 1994 the need for clinical investigations to evaluate the effect of dietary trans fats on insulin resistance. 3  One study found a higher risk of diabetes for those in the highest quartile of trans fat consumption. 2  Another study argues that there is no risk once other factors such as total fat intake and BMI (Body Mass Index, a measure of obesity) were accounted for. 2  However, I would argue that since trans fats are known to increase weight gain and abdominal fat (and thus also BMI), this factor should not be discounted.

  12. Liver Dysfunction.  The liver metabolizes trans fats differently than other fats.  Certain polyunsaturated fats are precursors to arachidonic acid (AA) prostaglandins, which are important to the functioning of cells.  The consumption of trans-versions of these essential fats interferes with (inhibits the action of) an enzyme  involved in this conversion (delta-4-desaturase). 1,2  It also causes adverse alterations in the activities of the important enzyme system (the mixed function oxidase cytochromes) that metabolizes chemical carcinogens and drugs (medications). 1

  13. Altered Hormone Activity.   Trans fat consumption is linked to increased breast cancer in women; and decreased levels of testosterone in male animals, increasing the level of abnormal sperm.  It also interferes with gestation in females. 1

  14. Fertility.  One study found “Each 2% increase in the intake of energy from trans fats, as opposed to that from carbohydrates, was associated with a 73% greater risk of ovulatory infertility...” 2

  15. Affects Infants. Trans fat consumption correlates to low birth weight in human infants; and lowers the amount of cream (volume) in milk from lactating females in all species studied, including humans, thus lowering the overall quality available to the infant. 1

  16. Affects Immune Response by lowering efficiency of B cell response and increasing proliferation of T cells. 1

  17. Affects Membrane Function.  Incorporation of trans fats into cell and mitochondrial membranes causes alterations in their physiological properties, including measurements of membrane transport and membrane fluidity. 1

  18. Escalates adverse effects of essential fatty acid deficiency by adversely interacting with conversion of linolenic acid to elongated omega-3 tissue fatty acids. 1

  19. Increases peroxisomal activity (potentiates free-radical formation). 1






return to Disease Menu  or Health Essays Menu

  1. Trans Fats in the News

  2. The Problem with Trans Fats

  3. Health Problems Attributed to Trans Fats

by Catherine M. Haug,  January, 2007 (moved from Hydrogenated Fats Article)