I was looking at my 10 month old boy the other day and marveling at the fact that he has quadrupled in size since birth, from 6 to 24 lbs. It dawned on me that the extra 18 lbs he didn’t have at birth had to come from only one place: the food that he eats. Somehow he has converted all that formula, breast milk, and mashed peas into 18 more pounds of brain, flesh, and bone. Even assuming he still has the 6 lbs he started with, he is now three quarters made up of what he eats, and soon will be almost entirely composed of what he eats. As adults, we often forget that the same holds true for us.

The fat, protein and carbohydrate in our diet serve many functions other than energy. They make up the cells in our body and provide the signaling that takes place between those cells. Every one of the billions of chemical reactions that occur in our bodies each day is dependent upon the nutrients we ingest. Change the inputs and the final product changes with it.

Clearly to operate at our best we need to have optimal – or at least adequate – nutrition. Unfortunately, convenience often trumps prudence when it comes to food choices, and those who provide our food (supermarkets, restaurants, packaged food companies, even our friends and family) aren’t necessarily offering us the best nutrition in the food we eat.

Take omega 3 fatty acids for example. At the height of our evolution, man’s dietary fat intake was anywhere from one third to one half omega 3. Over time, this proportion has dropped to about 1/30th, a ten-fold decrease. Why does this matter? Because it has serious implications for how your body functions, specifically with respect to your risk for heart attack and other inflammatory diseases.

Omega 3 fatty acids are the “good” polyunsaturated fatty acids that reduce inflammation in the body and block the chemical signaling that causes blood clots, both of which reduce the risk of heart disease and stroke. The omega 3 fatty acids in our diet are metabolized into prostaglandins, which are chemical mediators that inhibit inflammation and improve platelet function. More omega 3s translate to more prostaglandins and less inflammation. Omega 3s also affect cholesterol metabolism, reducing triglycerides and modestly increasing HDL (good cholesterol). This last effect is why we recommend omega 3 fish oil for patients with high triglycerides.

The opposite, pro-inflammatory, pathway in the body is dependent on omega-6 fatty acids in the diet. These are metabolized into arachidonic acid, which increases inflammation and platelet aggregation (promoting clot formation). Too much inflammation is closely correlated to our risk of heart attack and stroke. This is because a heart attack is caused by inflammation and subsequent rupture of cholesterol plaque on the arterial wall. Platelets clump on the ruptured plaque and the resulting blood clot blocks the artery completely. Arachidonic acid mediates both steps of this equation. In fact, arachidonic acid (omega 6) is so important that we give our patients at risk for heart disease medication to block its action. This medication is aspirin, and if you are taking a baby aspirin a day you are essentially taking medication to offset the omega 6 in your diet.

The inflammatory/anti-inflammatory balance in the body is largely dependent upon how much substrate (omega 6 or omega 3) is in the body. A healthy body should be about half and half, with equal balance of each side. Unfortunately, the typical diet is about 30:1 omega 6 to omega 3. So how can we fix this? By decreasing the amount of dietary omega 6, increasing the amount of omega 3, or (ideally) both.

The omega 6 in our diet comes primarily from vegetable oils and farm raised meats. Why farm raised? Because animals are what they eat too, and a vegetarian animal who exercises regularly has leaner meat and higher omega 3 content than an animal that sits around and eats corn meal all day. Corn has omega 6, not omega 3, so the farm-raised animal that eats corn has meat with a higher omega 6 content relative to free range animal meat. Decreasing the amount of vegetable oils and store-bought meat reduces the omega 6 levels in our diet.

Fish is the main source of metabolically active omega 3 in the diet, salmon most of all. Wild caught fish have higher concentrations of omega 3, since they dine on algae (also a good source). Farmed fish are a decent source of omega 3, just less so. Wild-caught or grass-fed meats are generally lean and have a high omega-3 content. Also, eggs fortified with omega-3 are available. Vegetables and nuts may contain omega 3 (flax and chia are good sources); however, only a small proportion of the omega 3 from vegetable sources is biologically active.