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My mom is one of the many people who believe that margarine is healthier than butter. However, when I ask my mom why she thinks margarine is healthier than butter, she couldn’t really give me a sound reason so I’ve always been skeptical of the idea. Today, I decide to look more in depth into the myth of whether or not margarine is actually healthier than butter and if so, what is the scientific reason behind it.

Butter has been around for about 10000 years (1). Margarine, however, was invented in 1813 by French chemist as a cheaper substitute of butter that could be used by armed force and lower classes (2). From my research, I found that the myth is surfaced around the idea of fats. Margarine is made mainly from vegetable oil, which contains a lot of “good” fat such as polyunsaturated and monosaturated fat and no cholesterol whereas butter is animal fat and is largely composed of saturated fat and cholesterol(3). It’s the general belief that good fat reduces LDL (bad cholesterol) level while bad fat, such as saturated fat, increases LDL and that higher LDL is associated with higher risk of cardiovascular disease. For this reason, people believe that margarine is healthier than butter. Even though it is true that good fat reduces LDL level, good fat is not the only type of fat that is contained in margarine, it also contain trans fat. So in order to see whether butter or margarine wins the health battle, let’s first discuss saturated fat and trans fat.  Saturated fat occurs mostly naturally. The popular idea that saturated fat is unhealthy started in 1950s with the Seven Countries Study that was conducted by Ancel Keys. This epidemiological study consisted of 12743 men, 40-59 years of age, living in 7 countries that are in different regions of the world. The result showed that death rate due to coronary heart disease( CHD) correlated positively with increase intake of saturated fat (4). In addition to the study, President Eisenhower’s heart attack in 1952 emphasized the negative connotation surrounding saturated fat. However, one loophole that was not familiar to the public was that Keys collected data from 22 countries, but only used data from countries that supported his hypothesis (5). In fact, a meta-analysis in 2010 by Frank Hu proved the Seven Countries Study wrong (6). The goal of the meta-analysis was to look at epidemiological studies to estimate the risk of cardiovascular disease (CVD) and stroke that was associated with increased intake of saturated fat. The meta-analysis included 21 studies, with 347,737 participants. There were 16 studies that considered the association between saturated fat intake with CHD and 62.5% (10/16 studies) showed non-significant association between the 2 variables. There were 8 studies considered association between saturated fat intake with stroke, and 75% (6/8 studies) showed non-significant association between the 2 variables. (Some studies were repeated for different measurements). Relative risk (RR) was the main measurement of this meta-analysis. Relative risk measures the ratio of a probability of an event occurring in an exposed group to the probability of event occurring in a non-exposed group. In this case, RR measures the ratio of having heart disease between higher saturated fat consumption and lower saturated fat consumption. If RR value is 10, then the chance of getting heart disease while consuming higher amount of saturated fat is 10 times greater than if consuming smaller amount of saturated fat. However, when eliminating 2 outliers, the average RR of 19 studies was only 1.07 for risk of CHD, meaning a person have about the same chance of getting heart disease whether he/she consume higher or lower amount of saturated fat. For this reason, it was concluded that there is insufficient evidence to say that increase intake of saturated fat increases risk of CHD, stroke or CVD.

Besides a very small amount that occurs naturally in beef, lamb, buffalo, majority of trans fat is man-made. Trans fat is made through a process called hydrogenation, where vegetable oil is exposed to high heat, high pressure and hydrogen gas. Since vegetable oil is liquid at room temperature and therefore cannot be used as spread, hydrogenation helps solidifying vegetable oil and turning it into margarine. Despite the perks of trans fat such as their long shelf life and their stability when frying, trans fat is found to have detrimental health effect. A meta-analysis was done in 1991 at Maastricht University to study the effect of replacement of saturated fat or unsaturated fat with trans fat on cholesterol level (7). The analysis extracted data from 12 studies, with 524 participants. Result showed that by comparing consumption of equal amount of calories from saturated fat or unsaturated fat, consumption of trans fat increases low density lipoprotein (LDL or “bad” cholesterol) while decreases high-density lipoprotein (HDL or “good cholesterol)  and increases the ratio of total cholesterol to HDL cholesterol, a powerful predictor of the risk of CHD (coronary heart disease).

Now, cholesterol is a tricky idea on its on. Saturated fat increases LDL (bad cholesterol) and so does trans fat. Therefore, the effect of LDL level will be similar for saturated and trans fat. Many people might assume that if the 2010 meta-analysis that was done by Frank Hu proved a non-significant relationship between saturated fat and heart disease, the same conclusion can be drawn for trans fat and heart disease and therefore the meta-analysis done at Maastricht University in 1991 is wrong. However, as I mentioned before, trans fat also decreases HDL (good cholesterol). That adverse effect on HDL by trans fat is what distinguish trans fat from saturated fat and that we must look at the ratio between LDL and HDL level to see the correlation for heart disease. It turned out that, the higher the ratio of total cholesterol to HDL (higher LDL and lower HDL), the higher the risk of cardiovascular disease (8). Thus, the conclusion in the Maastricht meta-analysis still holds true. However, if cholesterol is not enough to convince you that trans fat is worse than saturated fat then you’ll be happy to know that trans fat can cause other health issues. A study done at Wageningen University showed that consumption of trans fat impairs endothelial cell function (9). The study consisted of 32 subjects. and were divided into 2 groups, and were fed trans-diet and sat-diet for 4 weeks each. Trans-diet contained margarine that were high on trans fat and Sat-diet contained margarine that were high on saturated fat. The experiment measured brachial artery measurements. Brachial artery measures the maximum diameter of our blood vessels when they are exposed to certain stimulus. Result showed that the maximum diameter was 4.33 mm on the Sat-diet and 4.19 mm on the Trans-diet, meaning maximum diameter is smaller in consumption of Trans-diet. Smaller brachial artery diameter indicates decreased ability to dilate when exposed to stimulus. In other words, smaller artery vessels aren’t as flexible and are easier to break than bigger artery vessels. Hence, smaller brachial artery diameter is associated it with coronary artery disease and other atherosclerotic diseases.

What scientists do know about saturated fat is that it does have health benefits. Saturated fats are needed for energy, hormone production, signaling and stabilizing processes in the body. Therefore, consumption of a moderate amount of saturated fat is necessary for your health (10). According to the American Heart Association, a healthy 2000 calories diet should contain no more than 15 gram of saturated fat. Most butter brands  have 7 grams of saturated fat per tablespoon. Yes, that is a lot of fat but wait till you see the number for trans fat. Research has not found any health benefits that come with consumption of trans fat. Since trans fat is such a health hazard, it is recommended that we should consume no more than 2 grams of trans fat per day. However, the average amount of trans fat in just 1 tablespoon of margarine is 2.1g, exceeding the recommended amount (11). Seeing how trans fat is worse than saturated fat and that there is too much trans fat in margarine, it can be concluded that margarine is actually not healthier than butter. Therefore, the myth that margarine is healthier than butter is debunked. However, this conclusion might not be permanent. Many companies are reducing the amount of trans fat in their margarine so if one day, trans fat is greatly reduced in margarine to only 0.5 grams of trans fat (the amount of trans fat that is currently in most butter), then there will be a tie between margarine and butter.

Also, if you just love the taste and smell of margarine and would definitely not trade it with butter, then the rule of thumb is to buy tub margarine rather than stick margarine because tub margarine generally contains less trans fat since it’s not as solid as stick margarine.

Sources (1) http://www.dairygoodness.ca/butter/the-history-of-butter

(2) http://en.wikipedia.org/wiki/Margarine

(3) http://authoritynutrition.com/butter-vs-margarine/

(4) Seven Countries Study http://www.medeaterland.co.uk/public/link/allegato_13.pdf

(5) http://www.redorbit.com/news/health/1113089069/heart-health-and-saturated-fats-debate-editorial-030614/

(6) Saturated Fat and CHD Study  http://ajcn.nutrition.org/content/91/3/535.long

(7) Trans Fat and CHD Article  http://www.nejm.org.proxy.lib.umich.edu/doi/full/10.1056/NEJMra054035

(8) Trans Fat and CHD Study http://www.nejm.org.proxy.lib.umich.edu/doi/full/10.1056/NEJM199906243402511

(9) Trans Fat and Endothelial Function Study  http://atvb.ahajournals.org.proxy.lib.umich.edu/content/21/7/1233.long

(10) http://www.westonaprice.org/know-your-fats/importance-of-saturated-fats-for-biological-functions

(11) http://americablog.com/2013/10/margarine-really-healthier-butter-depends.html

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