Why The Long... Carbon Chain? The Role of Fatty Acids & lipids in the Human body

Fats have such a bad reputation in society today with obesity growing exponentially not only in America, but also across the globe. How much fat do we really need in our diets for our bodies to function properly? What kind of fats do we need, and what do we actually intake?

Lipids are biochemically important, essential nutrients to our body (essential fatty acids) that serve many functions to help maintain our everyday functionality. Lipids are formed from glycerol and fatty acids, commonly making triglycerides. In general, lipids are called fats in solid form and oils in liquid form, depending on their room temperature state and bonding structure. Lipids are the body’s second source of energy, next to carbohydrates and simple sugars. Lipids contain about 4000 kJ/100g of energy, placing it as the highest form of energy storage in the human body. Because of its more complex metabolic pathways, lipids are harder to break down than carbohydrates, and are commonly stored for later consumption if needed in adipose cells (fat cells), such as adipocytes, which expand in size as more lipids are stored in the cell, and shrink as they are released, burned, and used by the body.

Lipids function in the body as protective lining for the outside of organs, their presence in the hydrophobic tails of the phospholipid bilayer in cells, nervous function, thermal insulation (especially in other mammals, such as seals or whales), and buoyancy.

    So what do fatty acids structures have to to with the function they serve in the body, or more importantly, their effect on the body?

   
    Fatty acids are the basic building blocks of lipids, and their structure will correlate to the state of matter and effect on the body it has. The general structure of a fatty acid is a methyl group on one end (also called the omega end), a carboxyl end, and a long hydrocarbon chain in the middle, ranging from 12-20 carbon atoms long. Are there different forms of this structure? Of course. Saturated fatty acids have a complete “saturation” of hydrogen on each of the carbons in the middle hydrocarbon chain (2 Hydrogen per 1 carbon) since carbon can bond with four valence electrons, it bonds to the other carbons to the left or right of it, and then the last

two single bonds with hydrogen. However, if the fatty acid is unsaturated, it will form double bonds with the carbons since there is not enough hydrogen present to completely saturate the chain. Overall, a saturated fat will be a straight carbon chain, while an unsaturated fatty acid will bend or kink where there are double bonds. Due to this structure, saturated fats (animal fat products, such as butter or fat in red meat) can stack on top of each other, making solids at room temperature in the body. (Hint: See the problem?) However, due to the irregular shape of unsaturated fats (from plant oils, such as canola or olive oil), they cannot stack fatty acid chains and end up as a liquid at room temperature.

    Aren't trans- fats also saturated fats? They are supposedly bad for you.   

Well… yes, and no. Trans- fats are polyunsaturated fatty acids. What are those you ask? Well, both mono- and poly- unsaturated fats are, well unsaturated, but the prefix simply states how many double bonds the molecule has. Due to the number of number of double carbon bonds, some mono- unsaturated fats tend to be bent since the hydrogens that bond are both on the same side while some mono-unsaturated fats are straighter since the hydrogen are bonded on opposite sides, much like two weights balancing each other out. However poly-unsaturated fatty acids can have so many double bonds that they simply curl and twist upon itself. Both trans- fats and cis- fats are polyunsaturated fats, but act very differently in the body due to how they are formed.
    Trans- fats are actually the WORST possible fatty acid for the human body since it is a poly-unsaturated acid. (Wait, I thought unsaturated fats are actually healthier to eat than saturated fats?) Trans- fats under a chemical process called hydrogenation, which is used in food processing, that take a liquid unsaturated fat and bond more hydrogens to it to saturate it and turn it into something saturated that resembles saturated fats. But due to its chemical nature, these trans-fats are forced straightened either partially (not all the double bonds are saturated) or fully, and the body doesn’t know what to do with them.

On the other hand, cis- fatty acids are actually much healthier, as they are otherwise known as the omega -3, -6 fats, famous for supporting brain function and healthier hearts. Cis- fats are named so since it its the number of saturated hydrocarbons counted from the omega end (methyl group) till the first double bond.

So how does this all affect my health?

    In general, saturated animal fats pose a threat of Coronary Heart Disease (CHD) due to its  solid state of matter, which can build up against the artery walls as plaque, and if it breaks apart, can clog up smaller passageways and cause heart attacks in the extreme case, but in general higher blood pressure. Overall, diets rich in saturated fats, or even worse, trans-fats, lead to a higher risk of CHD. On the other hand, unsaturated fats tend to carry away cholesterol in the bloodstream, freeing up the passageways, extending and easing the work of the heart. Overall, if you can, avoid eating saturated fats or trans-fats in excess or even better none at all, and keep in balance unsaturated fats for a healthier diet and healthier life style.

Today, the large consumption of fast food and the acceleration of processed food in society and in our diet have lead people to obesity across the nation, and at the heart of it is the over-consumption of these saturated fats that are present in foods such as doughnuts, fried foods, frying oil, cream milk, coconut oil, and fatty red processed meat. Instead, there is good evidence from studies (Harvard nutrition: (http://tinyurl.com/6q6wac))proving alternative fatty acids essential to the body, such as omega-3 in fish and some nuts can reduce blood clotting and reduce risk of heart attacks and strokes while saturated and trans-fats is inversely correlated. These unhealthy fats can lead to an imbalance of LDL over HDL, increasing blood pressure, risk of CHD, atherosclerosis, and stroke.

More resources:

http://science.howstuffworks.com/innovation/edible-innovations/fat2.htm

http://www.webmd.com/diet/healthy-kitchen-11/omega-fatty-acids

http://biology.clc.uc.edu/courses/bio104/lipids.htm