Parent's Resource Center

Milk does a body good?

The billboard says, "Milk Does a Body Good!" For years, the National Dairy Council and your mother told you that milk is good for you and helps make you big and strong. Milk appears to be the answer to a people's prayers. Two cups of nonfat milk give you a big jolt of protein, over 170 calories, almost 80% of your daily calcium needs, and hearty quantities of vitamins.

Milk appears to be the answer to a people's prayers.

 

Milk is a central ingredient in many protein shakes and tastes great with cookies or cake. To many people with lactose intolerance, however, milk is a nightmare that causes stomach cramps, bloating, gas and diarrhea. Lactose intolerance is caused by lack of a digestive protein called lactase, which is critical for the breakdown of milk sugar (lactose).

People with this condition have difficulty digesting milk products -- a couple of glasses of milk wreak havoc on their digestive systems. To people with lactose intolerance, all the nutrients in the world won't make up for the price they pay for drinking too much milk. Many athletes are confused about lactose intolerance and the role of milk in their diet. While most are aware of the impressive nutritional content of milk, many are scared away by its potential for digestive-system distress.

Two cups of nonfat milk give you a big jolt of protein, over 170 calories, almost 80% of your daily calcium needs, and hearty quantities of vitamins.

 

A common belief is that milk causes bloating in everyone and should be avoided. Unfortunately, many athletes who have no problem digesting milk sugar are missing out on an exceptionally nutritious food source.

Here we answer the common questions about milk and bodybuilding. Get the facts before you turn sour on this nutrition basic.

What is lactose intolerance, and why can't some people tolerate milk products?
Lactose is milk sugar that cannot enter the bloodstream directly from the digestive tract. It must be broken down in the small intestine by an enzyme called lactase to form glucose and galactose before it can enter the bloodstream.

If you don't have enough lactase and thus the lactose is not digested properly, the undigested milk sugar moves into the large intestine, where it is consumed by bacteria that live in your digestive tract. There, the lactose can cause your gastrointestinal tract a lot of problems. It can pull water from the bloodstream into the gut and cause diarrhea. As the bacteria digest the lactose, they produce acids and gas that can cause bloating, cramping and flatulence.

Are some people more susceptible to lactose intolerance than others?
Because of heredity, about 75% of adults in the world have trouble digesting lactose. The exceptions are northern and some central Europeans, several people from Africa (Fulani and Tussi tribes) and some people from India. The remainder of the world's population has difficulty digesting lactose.

The National Institutes of Health estimate that 30-50 million Americans are lactose-intolerant -- about 20% of Caucasians, 70% of African-Americans and American Indians, and 50% of Hispanic-Americans. Intermarriage between races has decreased the number of people who can't digest milk. For example, lactose intolerance in Native Americans and African-Americans has decreased from nearly 100% about 50 years ago to 70% today because of intermarriage with people who have genes that allow them to produce lactase. The only way you can determine for sure if you have trouble digesting milk is to undergo simple medical tests.

SIMPLE TESTS

How can you tell if you have lactose intolerance?
Two useful medical tests help determine if you have trouble digesting lactose.

1) One test measures the increase in blood-sugar levels after consuming a beverage containing lactose (the equivalent of a quart of milk). If blood sugar levels go up significantly, that means you can digest lactose adequately.

2) A more sensitive test is to measure expired hydrogen gas after drinking milk. Significant elevation of hydrogen gas is evidence that you have trouble digesting lactose. The gas, which is produced by bacteria in the large intestine reacting with the milk sugar, will increase when you don't have enough lactase enzyme to break down the lactose. While you may experience abdominal cramps or diarrhea as a result of the tests, the procedures are not dangerous.

Many people who think they have difficulty digesting milk really don't have a problem. Recent studies have shown that lactose intolerance may be confused with other digestive disorders such as acid indigestion, ulcers, irritable bowel syndrome and intestinal gas. Taking drugs to ward off muscle pain, such as ibuprofen and aspirin, can also upset your stomach. Lactose intolerance is a trendy condition of the '90s. But just because your stomach hurts, don't automatically assume it's because of milk intolerance.

If I never had problems digesting milk in the past, can I develop problems in the future?
You can develop milk digestion problems at any age. Lactase deficiency can be caused by infectious diarrhea, some drugs, medical treatments such as surgery, radiation or antibiotics, and many diseases that affect the digestive system. You tend to lose your ability to digest lactose with age. By the time you become an adult, you usually don't have the same capacity to digest milk that you did as a child.

I love to drink milk but it upsets my gastrointestinal tract. Can I do anything to increase my lactose tolerance?
You can improve your ability to digest lactose just the way you can train your muscles. Studies have shown that people with lactose digestion problems who continue to drink milk can tolerate as much as eight ounces of whole milk a day because of adaptations by intestinal bacteria. People can increase their tolerance to milk products by eating fermented products such as cottage cheese, yogurt and hard cheeses. Products are available that predigest the lactose in the milk and make it almost lactose-free.

Completely avoiding milk products may make your problem worse. You need to take in some milk products to maintain the lactose-consuming bacteria. If you totally avoid these foods, you suppress these bacteria while the number of gas-producing bacteria increase. When this happens, you become much more sensitive to lactose in the future.

Can consuming milk products with a meal improve lactose tolerance?
Yes. Dr. Michael Martini of the University of Minnesota Department of Food Science and Nutrition found that drinking milk with a meal reduced digestive problems in almost 70% of the lactose-intolerant people in the study. Drinking milk with a meal improves lactose tolerance because it slows down the emptying time from the stomach. The lactose enters the intestines more gradually, so it is easier to digest.

SPECIAL PRODUCTS

Are there lactose digestive aids that will allow me to consume milk products?
Many companies market lactose digestive aids containing the nonprescription lactase enzyme B-galactosidase. These products are taken either orally to help your digestive system break down milk sugar or mixed with milk and then refrigerated for 24 hours while the enzyme breaks down the lactose.

The most popular lactose digestive products include Lactaid, Dairy Ease and Lactrase. Researchers at Baylor College of Medicine in Houston found that none of the products they tested had any effects on gas. However, they provided some relief of abdominal cramping and bloating. The researchers noted large individual differences in effectiveness of the products -- some people experienced much relief while others didn't notice any benefit.

Is acidophilus milk helpful for people with lactose intolerance?
Acidophilus milk is milk with a bacterial culture added. It is often recommended to people with a variety of digestive disorders, such as lactose intolerance, diarrhea and constipation, but studies have not supported its effectiveness. Acidophilus milk is also recommended to enhance large-intestine bacteria. However, the bacteria are largely destroyed by stomach acid before they reach the large intestines. The bottom line is drink acidophilus milk if you like its taste, but don't expect any health benefits.

If I'm lactose intolerant, do I have to give up milk products completely?
A recent study in The New England Journal of Medicine by Dr. Michael D. Levitt and coworkers of the Veterans Affairs Medical Center in Minneapolis, Minnesota, showed that many people who thought they had milk digestion problems really didn't.

Levitt states that even people who do have a problem can comfortably digest an eight-ounce glass of milk every day, particularly if they drink it with a meal. Another possibility is to drink lactose-reduced milk and milk products. These products, which are found in most supermarkets, include Lactaid and Vitamite. Products such as Mocha Mix Non-Dairy Creamer and Mocha Mix Non-Dairy Frozen Dessert are good nonmilk substitutes for cream and dessert toppings.

Severe lactose intolerance is rare, and you may be able to tolerate some products better than others. Thus a bowl of ice cream may cause no problems, while two glasses of milk will cause cramping and gas. Milk products are excellent food sources for people. Experiment with your diet. You will probably be able to include some of these foods in your nutritional program, even if you have problems digesting lactose.

CALORIE CONCERNS

Why is milk considered so fattening?
Because our traditional whole milk is fattening. Even so-called low-fat milk has considerable fat in terms of percentages of calories. Nowadays all of our favorite milk products, especially milk, yogurt and cottage cheese, are available in nonfat forms. Nutrition-conscious athletes usually choose nonfat and low-fat milk products.

MILK & MUCUS

Does drinking milk cause mucus formation?
Milk has been blamed for increasing mucus secretions since the time of the ancient Greeks. The evidence, however, is mixed. In studies of people with upper respiratory infections (colds), drinking milk had no effects on mucus production. However, in a study conducted at the New York University School of Medicine, people with asthma experienced a decrease in lung function after drinking whole milk but not skim milk. In that same study, milk had no effect on mucus formation or lung functions in people without lung disease. So, unless you have asthma, there is no evidence that milk causes an increase in mucus formation.

INTERACTIONS

Are there interactions between milk and drugs, such as antibiotics?
Milk may alter the effects of some drugs by interfering with their absorption and elimination. For example, absorption of tetracycline is decreased when taken with milk or other dairy products. Whole milk, because of the higher fat levels, affects drug absorption more than nonfat milk. Milk doesn't affect the absorption of all drugs, however, so it's a good idea to check with your pharmacist about milk's effect on any specific drug. Enteric-coated tablets (pills with a hard outer shell) leave the stomach mainly during the period in between meals (interdigestive period).

Drinking milk will nearly triple the amount of time it takes for one of the pills to leave the stomach. That's not a problem if the drug is supposed to be digested slowly. However, it may pose a problem if you want the drug to work rapidly.

That's why some pills should be taken on an empty stomach. After eating, the speed with which a coated tablet leaves the stomach is related to the caloric content of the meal. If you take a tablet early in the morning, you may not absorb it until late at night if you eat several meals and snacks during the day. This can alter the way the drug works and possibly cause harmful effects.

Does milk affect the absorption of any nutrient?
Milk decreases the absorption of iron into the body. Iron, which is deficient in the diet of many women athletes, is important for the health of blood cells. However, milk is one of the best sources of calcium, which is another essential nutrient. Calcium is critical for building strong bones and preventing bone loss (osteoporosis). Fortunately, the effect of milk on iron absorption is small. The nutritional benefits of milk far outweigh the slight inhibitory effect it has on iron absorption.

Milk, particularly whole milk, will delay the rate that food leaves the stomach. For that reason, it is a poor athletic fluid replacement beverage during exercise. When you're not working out, milk has little effect on the absorption of nutrients. Mixing the milk with chocolate may have a small effect on the rate that you digest it, if you have problems with lactose intolerance. However, if you don't have that problem, the added chocolate will have little effect on how quickly you digest the milk.

Is milk the best source of calcium?
Calcium is important for bone health. Many women athletes don't take in enough calcium, which can lead to loss of bone density, even at a young age. Milk is perhaps the best food source of calcium. Yet many people are reluctant to drink milk because of perceived problems, such as bloating, mucus formation and high caloric and fat content.

Drinking mineral water high in calcium or calcium-fortified orange juice, for example, may be an alternative for people who are lactose intolerant or don't like to drink milk. In most people, their bodies will absorb as much calcium from the mineral water as from milk. Calcium-rich mineral water is a good choice as a calcium supplement for athletes such as distance runners who may be calcium deficient and need to maximize fluid replacement.

REFERENCES

 


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Revised: November 14, 2006