Lactose Intolerance Essay, Research Paper
Lactose Intolerance: Another Painful Reason For Growing Up
Lactose intolerance (LI) is the inability of some humans to digest the lactose sugar contained in most dairy products and foods made with dairy products. LI has numerous readily apparent physical symptoms such as gas, cramps and diarrhea (Houts 110). More importantly, LI may lead to malnutrition in those people affected because of the loss of milk’s important nutrients. Not everyone is affected by LI. In fact, genetic background rather than any other health or cultural factor seems to best predict LI. The inability of humans to digest lactose has enormous health consequences, particularly among the poor populations of the U.S. and the developing third-world countries.
LI was first recognized in the 1960s when researchers found black children responding unfavorably to milk in their diets (Harrison 812). Research led to the discovery that lactose, the major sugar in milk and related dairy products, was undigestible in some people because they were missing the enzyme lactase. Lactase breaks down lactose into its component monosaccharide sugars, glucose and galactose. In people missing lactase, lactose passes undigested through the small intestine. In some people, the undigested lactose passes through the remainder of their systems with no ill effects. In others, however, the undigested lactose becomes viscous and ferments in the colon (Englert and Guillory 903). The thickness of the liquid and the fermentation cause painful cramping, gas and sometimes diarrhea. Besides not being able to digest lactose, these people suffer from malabsorption, which causes them to receive little or none of milk’s nutrients (Houts 110).1
The two major classes of LI are primary and secondary; both have the same ultimate symptoms and cause the same problems (Englert and Guillory 903, Houts 110). Primary LI is the natural loss of lactose tolerance from birth because of the loss of lactase, while secondary LI is generally caused by a nutritional problem or a sickness that results in a person’s inability to digest lactose. At birth, virtually all humans have lactase enzymes, and thus the ability to digest lactose. As people age, some of them lose lactase enzymes. The age when people start to lose lactase and the amount finally retained differ greatly, so people are affected by LI in varying degrees. Some people have virtually no tolerance to dairy products at all, while others are affected only mildly. People with zero tolerance levels normally must completely avoid milk products. Most lactose intolerant people, however, can tolerate differing amounts of lactose in their diets, depending on their lactase deficiency.
The three predominant methods of determining if a person is lactose intolerant are known as the lactose challenge test, the blood sugar test and the hydrogen breath test (Englert and Guillory 904). In all three of these tests the patient is given a known quantity of lactose (normally the amount found in one quart of milk), called a lactose load. In the lactose challenge test the effects of the lactose load such as cramping, gas and diarrhea are then carefully monitored. If a person has these LI symptoms, he or she is presumed to be lactose intolerant. In the blood sugar test, blood sugar levels are monitored through blood samples after the consumption of the lactose load. If the sugar level does not rise to a prescribed level, the patient is determined to be lactose intolerant because if the lactose had been digested the blood sugar level would have risen. In the hydrogen breath test the hydrogen level of the breath is monitored after ingestion of the lactose load. Higher than normal hydrogen levels will appear in the breath if the lactose is not digested because undigested lactose is fermented in the colon. Fermentation releases hydrogen which is absorbed into the blood and ultimately exhaled through the lungs. Once a person is determined to be lactose intolerant, the level of LI can be determined through careful evaluation of lactose intake in various foods. By finding the threshold of lactose susceptibility, lactose intolerant people can tailor their diets to match that threshold. These people can then consume milk products up to their threshold with little or no lactose related problems.
Although dairy products are the predominant source of lactose in our diet, there are many other non-dairy sources. Lactose is a sugar and is sometimes used as a sweetener in foods. Milk products containing lactose are also used as food enhancing agents. Foods such as canned fruit, lunch meats and cereals may contain lactose (Englert and Guillory 906). Regardless of the source of lactose in a person’s diet, the effects are the same on a lactose intolerant individual.
While most dairy products containing significant percentages of lactose cause LI, some high lactose dairy foods seem not to. Products such as sweet acidophilus milk and buttermilk may help digest lactose, but yogurt seems to be unique in greatly aiding lactose digestion.1 Even though some yogurts have a significant effect on lactose digestion, others have little or none. Factors such as the brand of yogurt or its preparation can affect the digestion of lactose (Wytock and DiPalma 454). Cheese products vary widely in their acceptability to lactose intolerant people. Like milk and yogurt products, the preparation and manufacturing processes used on cheese can drastically affect the ability of lactose intolerant people to consume these products. The variation among yogurts alone shows the difficulty for the food industry in preparing and manufacturing foods for lactose intolerant people as well as for the individual in choosing appropriate foods. Lactose intolerant people have options available besides the reduction of or complete abstinence from products containing lactose. Specially prepared products are becoming available with reduced lactose levels. Some new products have additives such as lactase to make them more tolerable, and capsules of lactase may be eaten with food to help digest lactose (McCarthy 11). Sometimes drugs to fight the symptoms of LI directly, such anti- diarrhea medications are effective.
The implications of not being able to utilize the nutrients in dairy products (especially milk) are far-ranging. Nutritionists recommend that a significant portion of our diet come from the dairy group. Dairy products are one of the four major food groups that we should eat from regularly for good health. If people with LI must avoid or reduce their intake from this important food group, serious malnutrition can result if their diet is not carefully supplemented to make up for the lost dairy products. Lactose intolerant women are especially at risk because there appears to be a link between LI and osteoporosis (Finkenstedt et al. 162). It seems that lactose intolerant women not only cannot digest lactose, but also cannot effectively absorb the important calcium content of milk products.
People in the U.S. who are lactose intolerant have many diet options to supplement the loss of milk’s nutrition. They can purchase specially prepared milk products that have little or no lactose content, they can choose foods from the other three food groups to balance their diet, or they can purchase lactase supplements. In other less-developed countries, however, the populations often do not have the variety of diet options we have in this country.
Except northern European countries, the problem of LI is more severe in most of the world than in the U.S., especially the less- developed, third-world countries (Harrison 815). Although the third-world countries tend to not have high native milk production, a significant portion of their foreign food aid is often milk products. In these countries where milk is expected to be one of the food staples to feed the starving, two trends are prevalent. First, milk is not being consumed because some find it unpalatable, while others do not drink it because the symptoms of LI are too much to endure. Second, because the percentage of LI is high among those consuming milk products, nutrition gained from milk product consumption by this group is minimal. For both these reasons, some of the developed world’s efforts to nourish the hungry are being wasted.
Americans as a whole are fortunate with respect to LI. The percentage of the U.S. population afflicted is estimated to be about 15% or about 30+ million people (Englert and Guillory 903). The remainder of the world, however, has a much higher incidence of LI. Non-European countries are especially affected, with Asian and African countries having the highest affliction rates (60-100%).1 How can these differences of LI among populations be explained? The prevailing theory is that genetics is the strongest indicator (Harrison 820, McCraken 481). Anthropologists have studied the world’s populations with respect to LI, and have concluded that genetics is the best predictor. People with northern European ancestries have the lowest LI rate (0-30%), while almost all other races have high LI rates (60-100%). It does not matter where people were born, where they currently live, or even their childhood or adulthood diets. Only their genetic background with respect to northern Europe descent affects their likelihood of being lactose intolerant. A good example of this is found in the U.S. Even though the U.S. has a comparatively low lactose intolerant population by percentage, American Indians are close to 100% lactose intolerant (Johnson et al. 385).
There is much speculation as to why genetics plays such an important role in LI, but the best theory seems to be natural selection (McCraken 496). Dairying (the raising and milking of animals for food) first appeared in northern Europe. It is speculated that during hard times, those individuals who were not lactose intolerant were better able to survive than those who were lactose intolerant. In times of marginal nutrition and caloric intakes, the edge went to those who could effectively consume dairy products. Of course, dairy products were not the only sources of food, but in some situations, the difference between surviving and dying could have been because of dairy products. Thus, through natural selection, people in dairying cultures became lactose tolerant. Cultures with little or no dairying, or those that used milk in different ways such as the making of cheese, had no reason to evolve toward lactose tolerance. Only in recent times has LI become a recognized world-wide problem, because of population movements, cultural changes with respect to diet, and food aid projects where milk products have been sent to susceptible populations.
LI is currently a substantial world problem and will most likely continue to grow, particularly in the U.S. Increased LI in the U.S. is likely for a number of reasons (Houts 112). The percentage of northern Europeans in the U.S. is declining because non-northern European families tend to be larger than northern European families for cultural and religious reasons. Also, there is a large and continuing immigration into the U.S. from Asian and middle eastern countries and Mexico. The lactose tolerant population of the U.S. is decreasing because of intermarriages between lactose tolerant and intolerant populations. While not every marriage of a lactose tolerant and intolerant couple results in lactose intolerant offspring, there is ultimately a dilution of the lactose tolerant population. Since the median U.S. age is increasing, and LI seems to increase with age, there is likely to be increased LI. Furthermore, as nutritional education in this country improves, people are more likely to consume foods more equally from the four food groups. Since most Americans currently consume too much meat by nutritional standards, further education could lead to more consumption of milk products, leading to a higher incidence of LI.
Although the percentage of the U.S. population affected by LI is relatively low, LI tends to be most prevalent among those least aware of the problem. Even worse, the sufferers of LI who understand LI’s problems are not generally in a position to address alternate diets, purchase supplements and so on (Reasoner et al. 54). As mentioned previously, blacks are very lactose intolerant. Many blacks in the U.S. also tend to be at low and poverty income levels, and thus are more likely to be part of food programs such as school lunch programs. Unfortunately, these programs generally have milk products as one of their high nutrition components. As a result, efforts to help the underprivileged are in many cases undernourishing them as well as making them sick.
Since LI is a growing U.S. and world problem, I believe we need to better educate people with respect to the existence of LI and ways of dealing with it. This is especially imperative in populations where a considerable percentage of people’s nutrition and caloric intake comes from milk products. People who are very lactose intolerant are in a sense lucky. Since lactose consumption causes them great discomfort, they severely limit their milk product intake. These people seek other forms of nutrition to supplement their diets. People who are mildly lactose intolerant are at comparatively high risk because they consume milk products with little or moderate discomfort, but believe milk is providing them with substantial nutrition. People at the greatest risk, however, are called malabsorbers. These people can consume “normal” daily quantities of milk products with no discomforting side effects, but they are actually receiving little or no nutrition from them. They are most at risk because milk may be a large portion of their perceived nutritional intake, yet they receive no nutritional return from it. Not being aware of this situation can lead to malnutrition. Women in this group are particularly at risk because of their high calcium requirement. There is evidence that malabsorbers not only do not absorb the component sugars of lactose, but the important calcium content of milk as well (Finkenstedt et al. 162).
I first became aware of LI a couple of years ago. From that time, until I worked on this report, I did not correctly understand the problem. I had heard that it affected all non- infants, regardless of their race. Since my original source of information was unreliable, I believed LI to be just another unsubstantiated rumor. Furthermore, I confused LI with lactose malabsorption, or the inability to derive nutrition from milk. I thought that everyone who was lactose intolerant could still drink milk, but that water would be the only nutrient they received from it. I had no idea that most people who are lactose intolerant experience varying degrees of discomfort when they consume milk products. I find it interesting and plausible that LI is genetically based rather than being caused by diet or other factors, although there is some dispute on this issue (Seakins et al. 878).
Since milk products are currently important to American diets, and increasingly so to third-world populations, I believe further education, food industry advancements and study of LI should be encouraged. Education will help people learn of the potential nutritional issues of LI and will help lactose intolerant people discover the reason they get sick every time they consume too much lactose. The food industry should be encouraged to provide better package labeling so people can easily determine lactose levels. Maybe a lactose quotient could be developed and printed on lactose based products to indicate their relative impact on lactose intolerant people. I think this would be a valuable service to lactose intolerant people in choosing products that contain considerable lactose but have different digestibility factors because of lactase or other additives. I believe study should focus on two major areas. First, alternate methods of processing milk products should be explored, such as making yogurts, cheeses and low-lactose products, and adding lactase to unadulterated milk products to help lactose digestion. Second, alternatives to foods containing lactose should be studied and promoted. This is especially important in food relief programs where our current efforts of sending high- milk diets to hungry people seem wasteful as well as dangerous.