Don't Cross Your Eyes...They'll Get Stuck That Way!: And 75 Other Health Myths Debunked (7 page)

Some people have digestive issues with milk or dairy. Those issues are real. But they also usually have more to do with diarrhea, bloating, or discomfort—not constipation. Lactose intolerance, in which people cannot digest the sugar called lactose found in dairy products, generally makes your stool loose and you gassy, not constipated. In fact, a study of people who reported sensitivity to dairy products did find an association between exposure to cow’s milk and increased immune system activation (with more immunoglobulins present), but the study found no statistically significant association with constipation. Even people who were sensitive to cow’s milk did not have any issues with constipation from dairy products.

There are very few good studies examining the relationship between cheese and constipation. But there is one particularly strong study. The National Health and Nutrition Examination Survey (NHANES) was put together by the National Center for Health Statistics in 1971–1975. They gathered tons of data on diet, exercise, and bowel dysfunction (among other data). In 1990, a group of researchers looked at data from the study for over 15,000 people age twelve to seventy-four. Overall, just under 13 percent of people reported constipation. When they did analyses on what those people were eating, constipated people reported eating less cheese, not more. They also ate less beans and peas, less milk, less meat and chicken, and less fruits and vegetables. They also drank more coffee and tea.

We’re not suggesting that diet has nothing to do with constipation. We’re also not suggesting that there aren’t people who have dairy issues. But no good evidence exists to implicate cheese in causing constipation in otherwise healthy people, and what evidence does exist, actually points the other way. Noah is going to be so pleased.

Chicken Soup

I have just the thing for that cold … Chicken Soup—TRUE

As myth busters, it’s sort of our job to dispel a lot of the “wisdom” that your mother and grandmother swore by. But one of Grandma’s best remedies may actually have something to offer when it comes to treating your cold. Yes, chicken soup might actually help relieve your cold symptoms.

We have to start off by saying that chicken soup has not been tested in rigorous, clinical studies. The evidence for or against chicken soup is not up to the standards of the studies that show us that medicines like antihistamines do not work for colds. However, experts have proposed several ways that chicken soup might work to help your body fight a cold or feel better during a cold. Chicken soup is a source of hydration and may improve your nutritional status: both good boosts when you are sick. The warm liquid may also help you better clear mucus from your body, especially from your nose. In a study that compared the impact of drinking hot water, cold water, and chicken soup, both hot water and chicken soup increased how fast the nose was running or helped to clear out the nose, but the chicken soup worked even better than the hot water alone.

It is also possible that chicken soup could have some special ability to kill cells involved with infections. And some experts have proposed that chicken soup might make you feel better by lessening your body’s inflammatory response to an infection, so that you don’t have as much mucus or as many aches and pains.

As mentioned, chicken soup has not been studied very rigorously in groups of sick or healthy people, but one group of researchers did carefully investigate the impact of chicken soup on the specific cells of the immune system that increase inflammation when you have an infection. When you have an infection, immune cells called neutrophils migrate to the area to help fight the infection. One of the things those neutrophils do is release chemicals that increase the amount of inflammation going on in your body. This inflammation is part of why you develop more mucus and phlegm when you have a cold. Though some of the inflammation response helps to fight off infection, other aspects of inflammation make you feel lousy.

Scientists studied whether chicken soup had an impact on the inflammation response. The scientists studied a homemade chicken soup, as well as commercially prepared soups, to determine whether chicken soup prevented the inflammatory cells from migrating or moving to the source of infection. Amazingly enough, chicken soup worked! Various dilutions of the homemade soup and the majority of the store-bought soups inhibited the movement of the neutrophil cells, which might give chicken soup anti-inflammatory properties.

Chicken soup is not proven to be an effective cold remedy, but it does have some properties that might help you feel a bit better. You may also experience the best kind of placebo effect from chicken soup. Having soup prepared for you by a loved one, or associating chicken soup with memories of someone taking good care of you, may play a powerful role in how much better chicken soup helps you to feel. Chicken soup is not the cure for the common cold, but the science suggests that it may be worthwhile to listen to Grandma on this one. You just might feel a bit better.

Chocolate

Chocolate or fried foods cause acne

Those of us with acne will try almost anything to improve our skin. Everyone wants clear skin. When you have pimples popping up all over, your parents and other well-meaning people often tell you to avoid chocolate or fried foods because these foods make acne worse. Many acne sufferers swear that they see differences in how bad their acne is based on what they eat. Whether or not your diet will sabotage your efforts to have clear skin is a question addressed by some interesting science.

Studies show us that people around the world believe that there is some link between acne and what they eat. The belief that particular foods make acne worse has been reported in studies of acne sufferers and their families from countries ranging from Greece to Britain to Jordan. Greasy food is most often reported as a cause of acne, perhaps reflecting beliefs that greasy skin and eating greasy food are linked. Nonmedical people are not the only ones who are not sure what makes acne better or worse; medical students, nurses, and family practice doctors have also been shown to have very limited knowledge about what worsens acne and what works to treat it.

The science about acne and what we eat is actually rather tricky to sort through. A number of studies have looked at how many people suffer from acne in different parts of the world. These studies find that acne is more common among adolescents in places like the United States and Canada than it is in certain parts of Africa or in other isolated places, like Papua New Guinea or among certain groups in Paraguay or Brazil. The low rates of acne in places where people are eating very different foods than we do in America make scientists wonder whether your diet really does make a difference for your acne. People in America and Canada do eat more chocolate and more fried, greasy foods than people in these other places. The problem with these studies is that other factors could also be making a difference in the rates of acne. Certain ethnic groups might just be less prone to developing acne. Or other factors related to the environment or skin care practices might play a role. The studies of how common acne is in certain places do not actually tell us that foods are to blame, and they definitely don’t tell us which foods might be to blame.

To try to find out whether certain foods are to blame, other scientists have tried to look more specifically at what people eat and whether they have acne. (Rachel really just cares about chocolate, so that is the one we will look at most carefully.) Chocolate, fried or greasy foods, and foods with a lot of sugar are often blamed for causing acne or for making your breakouts worse. We have often heard this debunked as a myth, but it took some research to look at all the evidence. Scientists have often tested these foods in regard to acne by testing whether the foods increase insulin resistance. Insulin is a particular hormone that helps the body absorb sugars, but it is also involved in a sequence of hormone responses in your body that has been linked to how we develop acne. Your body’s reaction to insulin can actually impact the other hormones, like androgens and retinoids, that are more directly linked to developing acne. Scientists have speculated that foods that make you more resistant to insulin might also give you more acne by increasing these other hormones. While studies of animals have almost always shown that foods with lots of fats (like chocolate or fried foods) increase the body’s resistance to insulin, many of the studies in humans have not found such a link between eating a lot of fat and having more insulin resistance. There is also no evidence that eating a lot of sugar (or having high glycemic indexes) makes humans have too much insulin or makes them resistant to insulin in ways that would cause acne. Whether or not eating a lot of fat or sugar changes the body’s resistance to insulin has important implications for problems like diabetes and obesity. Scientists need to do more work to figure out whether or how these foods impact the body’s long-term response to insulin. In the meantime, there is not definitive evidence that high-fat or high-sugar foods will increase insulin resistance in a way that causes you to have more acne.

The other hypothesis that scientists have tested is whether foods with more fat or sugar might increase how much sebum comes out of your pores. Sebum is basically what makes your skin oily, the natural oil of the skin. It is trapped sebum in the pores of your skin that gets inflamed and causes acne. Do fatty foods increase how much sebum you are making? Once again, some of the studies in animals show that animals do make more sebum when they eat more fat. In human studies, there is some suggestion that what you eat might change the amount of sebum your skin makes and how much fat is in that sebum. However, the human studies do not show that this change in the sebum impacts your acne.

Two studies have specifically tested whether chocolate impacts acne in humans. The studies did not have huge numbers of volunteers and were not designed as well as we would have liked, but both studies did not show any connection between chocolate and acne. In one of the studies, volunteers were given either chocolate bars or a fake chocolate bar that had similar amounts of fat and sugar. Those who were given the actual chocolate bars did not have any more acne, did not make any more sebum (skin oil), and did not have any changes in the composition of their sebum when they were compared to those eating the placebo bars. Several other small studies that asked people about their diets and about their acne found no connection between having acne and how much sugar they eat, how much chocolate they eat, shellfish, sweets, pizza, French fries, or other fatty foods.

A number of people have also questioned whether milk was to blame for acne breakouts. Because most chocolate contains milk, if milk is to blame for acne problems, this could also implicate chocolate. In several small studies, researchers have not found any connection between how much milk or other dairy products people eat and whether they have more acne. However, in a big study of thousands of nurses, there was an association between those who reported a history of having acne as a teenager and those who reported drinking more milk as a teenager. Scientists have come up with lots of theories as to why milk might cause more acne. In particular, they have speculated that hormones or other substances like iodine in the milk might make adolescents’ acne worse. These theories sound like they might make sense, but they haven’t been proven. And even the big study that connected milk intake and acne has some serious flaws. First of all, this kind of connection is an association, not causation. There is no proof that the milk
causes
the acne; the linkage can only say that they are correlated. Second, the data in the study relies on people’s memories of what they ate or drank. In comes the potential problem of recall bias that we have talked about before. It is very possible that if you had a problem like acne and you thought that milk might be involved, you would remember your milk-drinking more clearly than people who never had issues with acne.

Even though people all around the world believe that their diet affects their acne, there is no good scientific evidence that this is the case. Experts have developed ideas about how certain foods might make acne worse, but the scientific tests of these ideas let the foods off the hook! Both chocolate and fatty foods have been studied, and are not linked to acne. As is often the case, though, it would be great to have bigger and better studies to try to help us understand what really does make pimples pop up. In summary, there is no good scientific evidence to suggest that chocolate or fried foods are to blame for making your acne worse. A healthy diet should only include chocolate or fried foods in moderation; you can certainly enjoy these treats occasionally without pimple paranoia.

Cold Weather

Cold weather (and being underdressed for cold weather) will make you sick

Does the cold give you a cold? Around the world, people believe that cold or wet weather makes you sick. “If you go out in the cold or get too cold, you will catch a cold!” warn mothers and grandmothers everywhere. In studies from around the world, people report more colds when they are in cold, wet conditions. When Rachel is in Kenya, a country in East Africa that is directly on the equator, it is quite a bit warmer than in the middle of the United States where Aaron spends most his time; but if the temperature in Kenya drops just a little bit, everyone expects that they will get sick quickly because of the “cold.” Parents in the United States have the same fears as parents in Kenya. Sixty percent of American parents in one survey believed that changes in the weather cause colds, and 38 percent believed that cold weather causes colds. Just over half of the parents thought that not wearing enough clothes could cause a cold too. These were not poorly educated parents either; 48 percent had gone to some college or graduated from college, and an additional 35 percent had gone to graduate school.

Should we believe all of these reports of getting sick more often when it is cold? Not necessarily. When the question is studied scientifically, the answer is often quite different. Back in the 1930s, scientists studied the inhabitants of a small, freezing-cold island in the Arctic Sea to see how often they got sick. While they may have been bored on their cold little island, these islanders were not getting sick because of it. Scientists did not find any cases of colds during the winter, and the island inhabitants only started getting sick when the weather warmed up and outside ships brought in other people (including some with colds).