Advanced Nutrition Protein Carbohydrates And Lipid Biology Essay

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Effective July 1, 2008, trans fat was removed from the ingredient list of New York City's restaurants when the - New York City Department of Health passed the Trans Fat Regulation for restaurant food- Under the regulation, any artificial trans fat cannot be included in food items served by restaurants such as fry oils, spreads, baked goods, frozen foods, cannoli, and doughnuts. Trans fat is an ingredient that is widely used in food production since it was invented and brought to the market in 1900's because of its long shelf life, high melting point and ease of storage(1). Due to many studies showing that trans fat can possibly increase the risk of developing many medical problems such as cardiovascular disease, diabetes and obesity, scientists and researchers have started to focus on the health effects of trans fat upon the human body. Due to the possible adverse health effects to humans, FDA has required all food labels to indicate trans fat content since January 2006. Under FDA regulations, any food product with a trans fat content greater than 0.5g must declarr the trans fat content on the food label(2). Also, according to the guidelines from the American Heart Association, one's daily consumption of trans fatty acid should be less than 1% of total fat consumption(3).

There are two types of trans fat: ruminant source and industrial source. Industrial source trans fat is produced from hydrogenation or partial hydrogenation of unsaturated fat. In the carbon chain of the unsaturated fatty acid, there are one or more double bonds. During the hydrogenation process, extra hydrogen molecules are added to the carbon chain, thereby breaking down the double bond structure to a single bond. This will decrease the degree of unsaturation of the carbon chain. In the chemical structure of the natural form of fat, the hydrogen bonds are formed in the cis structure. In trans fat, however, these bonds are formed in the trans structure. Trans fat cannot be produced by the human body and only small amounts can be metabolized by our bodies.

Trans fatty acid can also found in animal products. Ruminants like cattle, sheep or goats have bacteria in the stomach that can convert the polyunsaturated fatty acids in livestock feed to trans fatty acid. The trans fat produced from biohydrogenation will be absorbed and stored in the animal's body. After the digestion, these trans fatty acid can be found in the fat or milk of these animals, such as beef fat and cow milk(4).

As we all know, trans fat consumption is associated with the risk of developing cardiovascular disease, but there is no significant study shows the difference on the effect of ruminant trans fat and industrial trans fat upon humans. According to a study done by Belanger et al., after the consumption of industrial trans fatty acid, the plasma levels of LDL cholesterol concentration in those studied that were significantly higher than the moderate consumption on ruminant trans fatty acid(5).

Many studies show that the consumption of trans fat is associated with the development of cardiovascular disease, diabetes and many chronic diseases. Here are several diseases that have been positively associated with the consumption of trans fatty acid:

1. Coronary Heart Disease (CHD)

Coronary Heart Disease is one of the adverse health effects related to trans fat consumption. In the human body, essential fatty acid like linoleic acid (LA) and linolenic acid cannot be produced. We must obtain these fatty acids from our daily diet. Linoleic acid is an important fatty acid for the formation of arachidonic acid (AA), a type of fatty acid that is used in the production of prostacycylin, which is a chemical that promotes blood flow. Kummerow states that trans fat may be incorporated into the endothelial cell membrane and inhibit the production of linoleic acid to AA, which means it also inhitbits the synthesis of prostacyclin. Lack of prostacyclin may cause blood clots, plaque formation and blockage of the arteries(6).

Trans fat is also related to cyclooxygenase- 2 (COX-2), an enzyme that is related to blood flow in the arteries. COX-2 is an enzyme that is required for producing prostacyclin. In addition, COX-2 may recognize the isomers produced during the hydrogenation, may inhibit the production of prostacyclin and react to the trans fat, causeing inflammation(6). Trans fatty acid may then combine with the endothelial cell membranes, thereby increasing the risk of developing inflammation. Lack of prostacyclin may cause blood clots and blockage of the arteries. Trans fat may also cause the calcification of the veins and arteries that causes blood clots. When the muscle cells in the heart lack nutrients, this may cause muscle death and heart attacks (7). Kummerow states that trans fat may become incorporated into the endothelial cell membrane and inhibit the transformation of LA to AA. AA is the substance that is necessary in prostaglandin production. Postaglandin is an important substance in regulating homeostatsis and the disease process(6).

The formation of the blood clot is associated with the Sudden Cardiac Death (SCD). (6) Almost half of the death from CHD is due to SCD. According to the studies done by Chiuve, a cohort of women who have CHF and consume trans fat or trans isomer may increase their SCD risk three fold(8).

2. Hypercholesterolemia and hypertriglyceridemia

Hypercholesterolemia and hypertriglyceridemia are another health problem that is associated with the intake of trans fatty acid. Consumption of trans fatty acid and saturated fat is related to the elevation of the serum lipid and lipoprotein level. According to Lindsay and Waldrop, elaidic acid is a fatty acid that contains trans bonds and is related to the elevation of low-density lipoprotein (LDL) as well as the decrease of high-density lipoprotein (HDL). In addition the elevation of LDL level is dose dependent. That means higher intake levels may have higher risk of elevation of LDL. Trans fat may have no effect, decrease the level of high-density protein or increase the ratio of the total cholesterol level to HDL level. High ratio is a risk factor of developing cardiovascular disease. (9)

In anther studies done by Matthan et al., the total and LDL cholesterol level of experimental subjects who consumed a hydrogenated fat diet was 7% and 12% higher than subjects who consumed a saturated- and unsaturated fat- diet, respectively. On the other hands the HDL cholesterol of subjects who consumed hydrogenated fat was 7% lower than those who consumed saturated fat. For the triglyceride level, the subjects who consumed hydrogenated fat had highest level; unsaturated fat, the lowest level. The study shows that the consumption of trans fatty acid (hydrogenated fat) is positively associated with hypercholesterolemia and hypertriglyceridemia (10).

3. Insulin sensitivity

Several studies show that trans fat consumption is related to the insulin sensitivity found in the overweight and in the diabetic population. According to a review of the study done by Micha and Mozaffarian, several randomized, cross-over studies with overweight or diabetic patients show that trans fat intake may increase both fasting and postprandial blood glucose insulin level but that it does not decrease the blood glucose level (11). On the other hand, there is no significant effect of fatty acid consumption on insulin sensitivity in young, healthy, lean men and women (12).

According to the study done by Salmeron et al., polyunsaturated fat may decrease the risk of type 2 diabetes, while trans fat may increase the risk. The study showed that replacing the 2% of one's trans fat consumption with polyunsaturated fat might decrease the risk of type 2 diabetes by 40% in obese, sedentary women (13). Studies have also shown that infants who consume breast milk with high levels of trans fat may have similar effects as adults, such as inflammation (9).

According to Kummerow, the epidemiological data from the CDC that relates to the harmful effect of trans fat upon human beings since the introduction of trans fat to the US market in the 1900s, shows that death from CHD increased from 265.4/100,000 in 1900 to 581/100,000 in 1950. Due to this large increase in the numbers of death from CHD, the government started to restrict the use of trans fat in food manufacturing. Possibly due to effective government regulation, nutrition education and promotion, the numbers of deaths from CHD have declined from 588.8/100,000 in 1950 to 217/100,000 in 2004(6).

In order to reduce the health risk related to trans fat, there are several things we can do that are recommended by the FDA (14):

Check the Nutrition Facts table on the food packaging. Under government regulations, if the trans fat content is >0.5g, it must be shown on the Nutrition Facts table. Food that is possibly high in trans fat content includes bakery products, shortening and margarine. Also, some dietary supplements may use the trans fat in their production.

Replace saturated or trans fat with mono unsaturated or polyunsaturated oil, such as olive oil, sunflower oil, canola oil or soybean oil. Even though these fats have been proven to lower the cholesterol level, we need to use them moderately; otherwise, they will cause unnecessary weight gain.

Consume moderate amounts of fish. Certain types of fish, such as sardines, mackerel and salmon contain omega-3 fatty acid, which is associated with promoting heart health.