Heart Disease and Metabolism

            When most people think of what kind of diet causes heart disease, they often think of fatty, greasy foods, and this may certainly be true for some people at risk. However, the term processed foods doesn’t just include lunch meats and sausages: the majority of processed food is from carbohydrates (sugars).  There may very well be more heart disease caused by consuming excess carbohydrates than excess fat. Why would this be true? In order to understand why, we need to understand how fats and sugars are broken down in the body and used for energy.

           Sugar is digested mainly in the mouth and the intestines, where it is then taken to the liver, often processed further, before entering the bloodstream. It is there that the important hormone insulin is released in order to send a signal for the body’s cells to take up the sugar from the bloodstream. The sugar is then broken down (metabolized) to completion, generating energy and heat. The body prefers to break down sugars first, followed by fats, and then proteins last. If sugar intake is at most moderate, the system usually works well, because almost all of the sugar will be burned for energy and heat, and then the remaining fat will then be broken down. The problem is when sugar intake is too much for the body to metabolize at one time. Normally, there is a modest level of fat breakdown going on in the body all the time. Unfortunately, when too much sugar is taken in, fat burning ends up slowing down while the body tries to get rid of the excess carbohydrates (1). Contrary to popular belief, excess sugar is not automatically converted to fat---it stays in the bloodstream until it is finally taken up by the body’s cells. In time, sugars can corrode the lining of the bloodstream (the arteries), contributing to heart disease.

            As was mentioned above, the hormone insulin is released in response to more sugar entering the bloodstream after a high-carbohydrate meal. The more sugar enters the bloodstream, the more insulin is released to help shuttle it into the cells. In theory, this is a good thing, but over time, the reality is much different. Excess insulin in the bloodstream does a number of destructive things to the body. These include: thickening the arteries, lowering the heart-friendly minerals potassium and magnesium, stimulating fibrous tissue in the artery linings that can form plaques, stimulating blood clot formation, and promoting increased oxidation of fats in the bloodstream (2). Equally bad is when insulin levels stay high in the bloodstream for long periods of time. The body’s insulin receptors try to adapt by becoming less responsive to insulin, a phenomenon known as insulin resistance. There is evidence that insulin resistance itself can be a major factor in the progression of heart disease (3).

            So far, we have only discussed the ways that excess sugar can cause heart disease. On the surface, it can sound strange that sugars can cause as much heart disease (or more), as fats do. If you are skeptical about the correlation between sugar intake and heart disease, take a look at the following statistics: in the 19th century, sugar consumption in America rose from 15 lbs per person per year to 85 lbs per person per year. As of 1993, sugar consumption averaged a whopping 135 lbs per person per year (4) (that’s almost six ounces of sugar per person per day, which is about 670 calories worth of simple carbohydrates). What about the rates of cardiovascular disease? In 1800, death from cardiovascular disease was uncommon enough to not be included in mortality statistics. In 1900, one in seven Americans died from this disease. By the 1990’s, a staggering one person in three died from cardiovascular disease (4).

            So, what about fat intake compared to sugar intake for causing heart disease? It is true that one of the risk factors for heart disease is excessive intake of the heavier meats, including beef and pork. However, not all meat is created equal. The average meat circulating around the country has hormones and antibiotics injected into the animal, along with both restricted movement of the animal combined with low-quality cheap feed. Health-conscious food stores usually carry range fed, hormone and antibiotic-free meat. This higher-quality meat is lower in an important inflammatory hormone called Arachidonic Acid (AA). Some people are very sensitive to the hormone AA, especially if they have allergies and/or asthma. If a person is still sensitive to the higher-quality range-fed meat, they can try soaking the meat in red wine overnight---the acidic properties of the wine will leach out much of the AA. Unfortunately, beef and other “heavier” meats are not the only source of AA---your body also makes it as well. Excess sugar intake ends up increasing your own AA production, and AA is a known contributor to heart disease (5).

            There is some evidence that some people are more genetically prone to either heart disease or diabetes---in other words, excess sugar intake may cause one person to develop heart disease, and the other diabetes. This means that different people handle sugar intake differently inside them. The factors mentioned above can make it very confusing and frustrating for a person to decide both what to eat and how much to eat. Many people reading this may have already tried many different diets, as well as clinical consultations. If the underlying diet-related problems are persisting, it would be a good idea to contact a nutritional consultant.

References: 

1.        Greenspan, F., & Gardner, D., p. 716. Basic & Clinical Endocrinology, 6th Ed. New York, NY: Lange Medical Books/McGraw-Hill Medical Publishing Division, 2001. 

2.         Kristal, H., & Haig, J., p. 102-105. The Nutrition Solution. Berkeley, CA: North Atlantic Books, 2002.

3.         Eades, M., & Eades, M., p. 34-35. The Protein Power Life Plan. New York, NY: Warner Books, 2000.

4.         Erasmus, U., p. 405. Fats that Heal, Fats that Kill, 14th Ed. Burnaby, BC (Canada): Alive Books, 1993.Sears, B., p. 137. The Zone. New York, NY: Regan Books / HarperCollins Publishers, 1995.

5.         Sears, B., p. 137. The Zone. New York, NY: Regan Books / HarperCollins Publishers, 1995.