Food prepared with unsaturated fats spoils faster than food prepared with saturated fats, so food manufacturers prefer to use saturated fats in their products. Many consumers are aware of the differences between the two types of fatty acids and prefer to buy products that they feel are healthier. Thus, some food manufacturers no longer prepare their products with saturated fats. Other companies have produced a modified unsaturated fat called a partially hydrogenated fat in which extra hydrogen atoms have been added to unsaturated fatty acids, converting them to a saturated form, but retaining the original chemical name indicating an unsaturated product.
Saturated fats contribute to the development of arteriosclerosis, or hardening of the arteries, which ultimately results in heart attacks and strokes. Fish oils, however, tend to be healthier than beef fats. Unsaturated fats do not contribute to clogging our arteries. With the exception of oils from the palm plant or oils from coconuts, which are higher in saturated fats than other plant oils, unsaturated fats are healthier for the body. The original pyramid grouped all animal foods with nuts and dry beans and made no mention of plant oils. The recommendations were an effort to decrease fat intake, which was good, but they also decreased the intake of helpful fats, which was harmful.
Carbohydrates create an interesting problem. When complex carbohydrates are broken down and absorbed from the digestive tract, their presence in the blood stimulates the release of insulin from the pancreas. Insulin facilitates the transfer of the sugar (glucose) from the carbohydrates into the liver, muscle, and body fat. Once inside these three types of tissues, the sugar is metabolized or stored. If the body has more sugar than what is necessary to burn, the sugar is stored, mostly as triglycerides (see Chapter 2), a principal component of body fat. The more sugar a person eats, the fatter the person gets. The more glucose the body has in the blood, the higher the levels of insulin released to handle the sugar. If a person eats a meal that gets glucose into the blood rapidly, the person's blood glucose concentration increases quickly with a corresponding high insulin level. The current theory on the development of type 2 diabetes states that if these spikes of glucose and insulin occur frequently, the liver, muscle, and fat tissues may lose sensitivity to insulin. Thus, the body can no longer eliminate glucose from the blood adequately, resulting in the development of diabetes.
Different types of carbohydrates are broken down and absorbed at different rates from the digestive tract. Whole grains break down slowly, while refined grains break down quickly, flooding the blood with glucose. As stated above, the rapid rise in glucose may contribute to the development of diabetes, but it also causes more of the glucose to be converted to fats for storage. This fat storage contributes to obesity, if the energy is not used in exercise. The original pyramid did not differentiate between these types of carbohydrates.
The average American diet is now fairly close to the Food Guide Pyramid of 1992, but with a heavier emphasis on animal products than recommended. Daily, a person eats about seven servings of bread, cereal, rice, or pasta; about five servings of meat, fish, poultry, eggs, nuts, or dry beans; three servings of vegetables; three servings of milk, yogurt, cheese, and fruit; and fats and sweets have risen to the top tier.
The Harvard researchers constructed an alternative pyramid called the Healthy Eating Pyramid (Figure 8.2b). This guide takes into account the differences among types of fats and carbohydrates. The new pyramid focuses on individual foods and is designed for lifelong health, not short-term weight loss. The term "servings" has been replaced with the number of times a day the food should be eaten. Instead of four tiers, there are seven (daily exercise has been added).
There may still be a need for refinements in this pyramid scheme. It treats all plant oils as equals, except for palm and coconuts, when some plant oils are better than others. Also, few people would equate rice and potatoes with a chocolate candy bar, but the makers of this pyramid have. Still, this pyramid is probably better than the 1992 suggestions and does attempt to differentiate between good and bad forms of fat and carbohydrates, making it a little easier to eat a healthy diet.
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