Everyone knows that trans-fats are bad for our health, but do we actually know why?

According to published studies in various medical journals here is a list of some of the negative effects these bad fats have in our bodies:

• Lowers HDL (your good cholesterol)
• Raises LDL (your bad cholesterol)
• Raises total cholesterol 20-30%
• Correlates with low birth weight in humans
• Increases insulin response (which causes weight gain)
• Alters your immune system – depresses B Cells, increases T Cell (increases allergies)
• Decreases testosterone, abnormal sperm
• Decreases red blood cell response to insulin (this causes fatigue)
• Alters liver detox pathways
• Alters cell membrane transport and fluidity (makes cells ‘leaky’)
• Increases free radical production (causes cell damage & aging)
• Precipitates childhood asthma
• Decreases visual acuity in infants
• Breast milk will concentrates trans-fats so babies receive an even higher dose

If we look at the history of trans fats, they were developed to make food products containing polyunsaturated fats last longer on the store shelf. This was accomplished by taking a fat that is normally liquid at room temperature, eg. vegetable oil, and turning it into a solid, eg. margarine.

In order to turn these liquid fats (oils) into solids, a process called hydrogenation is used. This is when you take a single bond and turn it into a double bond by adding hydrogens. When you make these double bonds they can either have a "cis" formation (hydrogens are on the same side of the double bond) or a "trans" formation (hydrogens are on the opposite side of the double bond).

Now I'm sure you're wondering, what is the benefit of turning an oil into a fat, and how does that improve shelf-life? It turns out because of their chemical structure, liquid oils are more susceptible to oxidation and therefore rancidity when compared to their solid oil counterparts. That means they will go "bad" quicker. Shorter shelf-life equals less profits. And since naturally occurring fats that are solid at room temperature, like butter and lard were mistakenly vilified, manufacturers needed a new solution - enter trans fats.

Now most people, if asked, would like to avoid trans fats, but food manufacturers don't want you to stop eating their products. So how do they get around this terrible inconvenience?

Well they have many tricks up their sleeve like, "low in trans fat" - this translates into "this product has trans fat below a certain number" or "trans fat free" - this translates into "this product is trans fat free until you cook it" or they don't even list trans fat on the label. You can be sure if you are reading the ingredient list and it contains partially hydrogenated or hydrogenated oils listed you are eating trans fat.

It is not because I prefer "natural" items like herbs over pharmaceuticals that I recommend butter over margarine. It is because of an understanding of basic biochemistry.

Now I would love to hear from you! What foods could you be eating that have trans fats in them? What is one change you have made in your diet to avoid trans fats? Leave your comments below and I will be back next week with another Doctor as Teacher Tuesday.