Large study identifies trans-fats as the risk factor for heart disease, not saturated fats.

Fats, we love to eat them but they are often the target of much hate from the latest health crazes. They make you fat, they clog your arteries, or they give you heart disease. The problem with most of our understanding of fats is that they are all created equal. This is not the case, some of them are good. There are three types of fats: unsaturated, saturated, and trans-fats.

  • Unsaturated fats are generally considered the healthy fats, they are your omega 3’s and 6s. They can be found in nuts, avocados, and vegetable oils (olive and canola). Unsaturated fats have a kink in their structure (caused by a double bond) that prevents them from being packed together too tightly. This is why unsaturated fats are liquid at room temperature.
  • Saturated fats are usually been considered less healthy than unsaturated fats although the effect of them on our overall health is still unclear. It is generally believed that moderate levels of saturated fat intake are fine but over consumption of them can cause problems. They are found in butter, cheese, cream, and fatty meats. Saturated fats have no double bonds so their structure is straight and can be packed together tighter. This is why butter is solid at room temperature.
  • Trans-fats are unsaturated fats that have been hydrogenated (adding Hydrogen’s). The fat still contains a double bond but now there is no kink so the fats can be tightly packed again. This process makes them solid at room temperature, similar to saturated fats. While most trans-fats are from industrial processes, there are naturally occurring forms of trans-fats in animal fats like lard. Foods high in trans-fats include fast food, fried food, baked goods, some margarine, and snack foods. Trans-fats are preferred for deep frying because they can withstand the high heat for longer before they become rancid.
fat-molecule

Notice the kink in the unsaturated fat, this is caused by a double bond (blue) in the chemical structure. There is also a double bond in the trans-fat but no kink in the structure.

While it is well known that unsaturated fats are healthy and should be a major component of our daily fat intake, less is known about the risks associated with saturated fat consumption and heart disease. To address the question of saturated and trans-fats on heart health, a paper published in the British Medical Journal performed a large scale statistical analysis that combined the results of previous research, called a meta-analysis. They analyzed the association between saturated fats and atherosclerosis, death by heart disease, and mortality (regardless of cause) in 90,500 to 340,000 people. They then analyzed the same factors in relation to trans-fats in 12,900 to 230,000 people. The results give us some pretty convincing evidence as to the true culprit in heart disease.

In the results, saturated fat intake was not association with all cause mortality, cardiovascular mortality, or atherosclerosis (plaques in the vessels). There was also no association between consumption of saturated fats and strokes or type 2 diabetes. When looking at trans-fats consumption, there was a significant risk for all cause mortality, cardiovascular mortality, and atherosclerosis. Specifically, people who consumed trans-fats were 34% more likely to die, 28% more likely to die from heart disease, and 21% more likely to have heart disease. No associated between trans-fats and strokes or type 2 diabetes was found. When separating the industrial trans-fats (those found in margarines and fast food) and the trans-fats from lard, industrial trans-fats were found to be associated with heart disease and cardiovascular death but more naturally occurring trans-fats were not.

There has been a large movement to ban trans-fats from our food because of results like these. Trans-fats are dangerous and are likely fuelling the heart disease epidemic. Heart disease is responsible for 820 deaths per 100,000 people in 2013. Consumption of trans-fats could be associated with as many as 230 of those deaths per year. While saturated fats may not be associated with heart disease, over consumption of them can lead to obesity and elevated levels of cholesterol. These can cause other health problems. Replacement of saturated fats with healthier unsaturated fats is generally considered a wise and healthy choice.

The reason this study is so important is that people may believe replacing their saturated fats with carbohydrates is a healthier option. Emerging evidence is finding that this is not the case. When some saturated fats are replaced with refined carbohydrates (sugar) or high glycemic index foods the risk of heart disease increases. So what is the take home message? Trans-fats are bad, very bad. Saturated fats are not great but not bad. Unsaturated fats are great. Eliminating trans-fats from your diet is a smart idea and replacement of some saturated fats with unsaturated fats can lead to some modest health benefits. Remember, everything in moderation, except trans-fats. Stay away from them.

Photo credit: Flickr Tantek Çelik

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