"Public health is purchasable. Within a few natural and important limitations any community can determine its own health."-Hermann M. Biggs (1859-1923)
The science of medicine has changed substantially in the past several centuries. The discovery of microorganisms as the cause of infection was one of the greatest advances. Knowing how diseases are caused and spread has led to improvements in hygiene and the development of vaccines to prevent diseases. Antibiotics allow patients to quickly recover from bacterial infections that would have been deadly a century ago.
Why do we need vitamins?
More than 2,300 years ago, scurvy had been identified as a disease that strikes sailors on long journeys. The body of a person suffering from scurvy has trouble producing collagen, a component of connective tissue. Its symptoms include bleeding gums, loss of teeth, severe joint pain, slow healing of wounds, and even death. British sailors became known as Limeys after it was discovered that eating citrus fruits on long voyages prevented scurvy. Today we know that people contract scurvy when they do not ingest enough vitamin C, one of a group of substances needed in small amount for the body to function properly. Why do we need vitamins?
A vitamin is an organic compound (a compound based on carbon) that an organism needs but cannot produce in sufficient amounts, if at all. Your body can produce one, vitamin D, in your skin—but only in response to sunlight. So if you live in an area with limited sunlight, you will need additional vitamin D. In the United States, vitamin D is generally added to dairy products. About one third of the vitamin K that you need is produced inside your body, although not by your own cells. Bacteria in the intestines produce the compound and you absorb it through the intestinal walls. Most of the vitamins that you need are available in a well-balanced diet, although sometimes supplements are helpful.
Vitamins play an important role in a wide range of functions within cells, tissues, and organs. Each vitamin has many different roles within your body, so a vitamin deficiency can have many symptoms, which do not always seem to be related. Vitamin A, for example, is important for vision because it is the only source for retinal, a compound required for the rods and cones in the eye to function, so lack of vitamin A is often associated with vision problems. It also plays a role in skin health and in the immune system, so a deficiency of vitamin A can also cause acne and a tendency to develop infections easily.
An enzyme is a protein used by a living cell to control the rate of a chemical reaction. Many of the reactions inside the cell could not occur at body temperature without the help of an enzyme.
There are six vitamins in the group of B vitamins. Among other roles in the body, they work with enzymes to convert food into energy and to build new cells. Most of the B vitamins are found in fresh fruits and vegetables. Some of them are also available in meats and dairy products. Most breakfast cereals are fortified with B vitamins. Because they are involved in so many different functions, a deficiency of these vitamins can cause a variety of symptoms, including diarrhea, skin problems, headache, weakness, and nervous system disorders.
Most people know that citrus fruits contain a lot of vitamin C, but other good sources include broccoli, green peppers, and most fruits. Vitamin C is necessary for humans to produce collagen, a protein fiber that connects organs and tissues throughout the body and gives structure to cells. Signs of a deficiency of the vitamin include muscle and joint pain, loose teeth, and easily damaged blood vessels, which causes easy bruising and slow healing. Vitamin C also removes chemical substances that damage cells and provides protection against disease.
Vitamin D is necessary for the processes that control the distribution of elements, such as calcium and phosphorus, in your bones. One of the obvious symptoms of diseases, such as rickets, which are caused by a shortage of vitamin D, is weak or deformed bones.
Vitamin E protects your body from some of the aging processes by reacting with chemicals in your body that damage cells and increasing the flow of oxygen to cells. Your heart and lungs depend on vitamin E, as well as the red blood cells that carry oxygen throughout your body. When you do not get enough of the vitamin, these tissues break down and do not work as efficiently. Foods that provide vitamin E to your diet include nuts, whole grains, seeds, and spinach.
While some of the vitamin K that you need is made in your intestines, most of it must come from your diet from leafy green vegetables, meat, and dairy products. Vitamin K is necessary for strong bones and in the clotting of blood. Signs that you have too little vitamin K include a tendency to bleed or bruise easily, and brittleness in bone tissue.
Vitamins are good for you, so it may seem that taking more of them is better. It is possible, though, to get too much of a good thing. Vitamin C and the B vitamins dissolve in water, so your body easily gets rid of any excess. The other vitamins, however, tend to dissolve in fatty tissues in your body. If you ingest more of them than your body needs, they accumulate and can eventually become a toxin. Overdoses of the fat-soluble vitamins can cause insomnia, fatigue, and high blood pressure, among other symptoms. It is unlikely that you would overdose as a result of a normal diet, but you need to be careful not to take excess vitamin supplements.
Is cholesterol really bad for you?
We have all read warnings about too much cholesterol in our diets. Depending on what article you read, eggs, meat, and dairy products are either essential parts of your diet, hazardous to your health, or both. And then, you also hear about "good" cholesterol and "bad" cholesterol. So is cholesterol in your diet really bad for you?
Cholesterol is a waxy substance that your body uses when it builds cell walls. It is also necessary for the proper manufacture of vitamin D and some hormones. Cholesterol is manufactured in your liver and then distributed to cells in the bloodstream. The problem with cholesterol is that it does not dissolve in blood. Instead, it is carried by proteins.
There are two forms of protein-cholesterol complexes: low-density lipoprotein (LDL) and high-density lipoprotein (HDL). This is where good and bad come in. Although both forms are always present and are necessary for your body to function, an excess of the LDL form ("bad") can cause problems.
LDL carries cholesterol from the liver to the rest of the body. When there is too much of it in the blood, deposits form on the walls of arteries, making them less flexible and blocking the blood flow. If the arteries become too constricted, these blockages can lead to a heart attack or a stroke. On the other hand, HDL carries cholesterol from the blood back to the liver, where it is discarded. By carrying away and reducing the amount of cholesterol, HDL reduces the deposits on the arteries, making HDL the good guy. Within the normal range of total cholesterol, a high ratio of HDL to LDL reduces risks of heart attack or stroke.
Recent research indicates that limiting the cholesterol in your diet is not the most effective way to control the cholesterol in your blood, which is where it does the harm. In general, reducing dietary cholesterol has a relatively small effect on the blood concentration. For most people, about 75 percent of the cholesterol in the blood is made in the liver. If you have high cholesterol, even a small reduction is helpful, but there is a more effective way to attack the problem.
It appears that the best way to control cholesterol is to eat a diet that is low in specific types of fat. Saturated fats, which include most animal fats—meat, dairy, egg yolks—and some vegetable fats—coconut and palm oils—tend to raise cholesterol. Because they raise both the LDL and HDL levels, the overall effect of saturated fats is negative, so their consumption should be limited.
Although high cholesterol levels are often associated with being overweight, people with any body type can have high cholesterol, particularly if they have a diet high in unsaturated and trans fats. Because there are no noticeable symptoms of high levels, you should have your cholesterol checked regularly.
Another form of fat, called trans fat, actually decreases HDL while increasing LDL in the blood. Trans fats are produced by the addition of hydrogen to the fat molecules in vegetable oils. These fats, found in stick margarine, many snack and processed foods, and commercial deep-fried foods (such as french fries) should be eliminated from the diet if possible because of their strong negative effects on cholesterol.
A third type of fat, unsaturated fat, actually reduces LDL levels while increasing HDL levels. These fats are found in most vegetable oils, including corn, sunflower, soybean, canola, and olive oils.
Do spicy foods cause stomach ulcers?
Stomach ulcers are potentially deadly holes in the stomach lining that can cause severe pain and internal bleeding. In severe cases, the hole can pass completely through the stomach lining and allow its corrosive contents to escape into surrounding tissue. Thirty years ago, if you had asked any doctor what causes stomach ulcers, the answer would include one or more of these factors: stress, spicy food, and alcohol. Today, you would get a completely different answer. If spicy foods don’t cause ulcers, what does?
For the past century, the treatment for ulcers was bed rest, a bland diet, and antacids. These treatments helped reduce the discomfort but the results were generally not permanent. The pain returned when the treatment stopped. Recent research showed that stress, spicy foods, and alcohol can make the symptoms of ulcers worse, but they do not cause them. Most stomach ulcers are the result of a bacterial infection in the stomach lining. So what is the best treatment? Antibiotics cure ulcers by killing the bacteria with a month or two of treatment.
The discovery that ulcers are caused by microbes was a surprise to most medical professionals. Now research is underway to find out whether other common diseases, including arthritis and atherosclerosis (hardening of the arteries), may also be caused by infections.
The bacterium that causes ulcers, Helio-bacter pylori, was first discovered in 1982 by researchers in Australia, who later won the Nobel Prize in Medicine for the discovery. Up to that time, no one had expected any bacteria to be able to survive the acid conditions of the human stomach.
The hypothesis that ulcers was caused by an infection was not immediately accepted. One of the researchers, Barry Marshall, actually caused an infection and ulcer in his own body, and then cured it with antibiotics to provide additional evidence. This is not a research practice that is generally encouraged.
After scientists knew to look for H. pylori, they found that about half of the people in developed countries, and almost everyone in some parts of the world, have the bacteria in their stomachs. The infection apparently begins in childhood and continues for life. However, only 10 to 15 percent of people with the bacteria develop ulcers. Researchers are now working to find out why some people develop these symptoms of infection while others do not.
How do bacteria become resistant to antibiotics?
When antibiotics were first introduced in the 1950s, they were a wonder drug. For the first time in history, many deadly diseases were under control. Infections that previously had been life-threatening could be brought under control in a few days and completely cured within weeks.
Unfortunately, some of the wonder has worn off. Bacteria have shown an ability to resist the effects of antibiotics. Some infections are barely controllable and some antibiotics that were once very effective are now practically useless. What causes antibiotics to become less effective?
For many bacteria, the inside of your body is the perfect habitat—warm and moist with a constant flow of nutrients. Many of them co-exist peacefully with you and some are even necessary for your body to function. Others are invaders who produce chemicals that are toxic or reproduce rapidly, taking nutrients needed by your cells. When these invaders are detected, the immune system reacts to destroy them.
Generally, the fight between bacteria and your immune system goes on, day and night, without your awareness. Sometimes, however, the bacteria get the upper hand and start reproducing out of control. Then your defense systems kick into high gear in an attempt to wipe out the invaders. Many of the symptoms of an infection— including swelling, high temperature, and redness—occur as the immune system fights the bacteria. If the bacteria reproduce too quickly, the infection can cause severe damage to tissues and organs, and even death.
Antibiotics help the immune system by killing the bacteria. They are poisonous to particular bacteria but not to the cells of your body. They interfere with the bacterial cell by disrupting normal functions, such as building new cell walls, blocking DNA synthesis, or disrupting its metabolism so that it cannot produce necessary compounds, such as proteins. As a result, the bacterium dies or is not able to reproduce and the infection and its symptoms go away.
Unfortunately, bacteria are sometimes able to avoid the effects of the antibiotic. There are several ways they can survive. Sometimes they change the structure of the membranes that allow chemicals to pass into and out of the cell, keeping the antibiotic compound from entering the cell. Another defense technique is changing the structure of an enzyme or other compound that is the antibiotic’s target. Another way a bacterium can protect itself is to destroy the antibiotic before it can do any damage.
How do bacteria learn to protect themselves? Actually, it is not a learning process. What happens is that an individual organism develops immunity to the antibiotic. When it divides, its descendants are also immune. As the other bacteria around them are destroyed, this colony has more and more access to resources, so it thrives.
Definition
A mutation is a change in the genetic sequence in the DNA of an organism. Mutations can be caused by errors during making DNA molecules or by exposure to radiation or chemicals. If mutations increase the chance of an organism’s survival, they are likely to be passed on to future generations.
The initial resistance can come from a mutation, or change in the DNA of a single organism. If the mutation protects the bacterium from the antibiotic, it reproduces and an antibiotic resistant strain now exists.
Another way to get resistance is to pick it up from other bacteria. Antibiotics do not kill all types of bacteria, so there are always harmless species around that are immune. Sometimes a harmful bacterium can join with a bacterium of another species, mixing their DNA. In other cases, it can scavenge DNA remnants from dead bacteria. DNA that makes the antibiotic harmless can then lead to an antibiotic-resistant strain.
Antibiotics are not the cure-all that they were once believed to be. They are only effective against bacteria, while many diseases are caused by viruses. One major reason for the development of antibiotic-resistant bacteria is the tendency, in the past, for doctors to prescribe antibiotics when they were not necessary. Overuse of antibiotics has led to many strains of bacteria developing resistance.
Why do flu epidemics seem to start in Asia?
Flu epidemics can travel rapidly through the population. We go to clinics to get shots to protect us from flu and to slow its spread. It seems as if there is a new epidemic predicted every year and new strains of the virus appear regularly. If you watch the news, it seems that these epidemics usually start in Asia. Do flu epidemics really start there, and if so, why does this happen?
Influenza, or flu, is caused by a virus that works its way into cells and takes over. Then, instead of operating normally, the cells begin to produce new viruses, which attack more cells. Many of the uncomfortable symptoms of flu occur as your body fires up the immune system to fight the invasion. Other symptoms—such as coughing, sneezing, and lung congestion—occur as dead cells, killed by the virus invasion, accumulate in tissues.
Generally, after your body has fought a virus once, the immune system "remembers" it and delivers a knockout blow quickly when the next invasion starts. Sometimes though, a small change in the virus structure can hide it from the system. Then your body has to learn to fight it all over again.
Fast Facts
Pigs are also a source of flu viruses that can infect humans. Both human flu viruses and bird flu viruses can live in their bodies, providing an opportunity to exchange genetic material. This leads to occasional outbreaks of "swine flu" in humans.
One of the reasons that flu can become such a problem is that there are many different strains of the virus. Some of them infect only people. Others infect animals such as birds, horses, and pigs. Normally these viruses are not a problem for people. However, viruses occasionally mutate and gain the ability to pass from one species to another. Influenza viruses have eight segments of genetic material, two of which determine whether the virus is able to infect a particular type of host. Viruses are able to swap genes with one another, so if human and animal viruses come together, a new virus can form.
Avian flu viruses occur naturally in bird populations around the world. Although wild birds carry the viruses, they usually do not get sick from them. The viruses are very contagious, though, and domestic birds, such as chickens, ducks, and turkeys can contract flu from the wild birds.
Mutations in viruses and transfer of DNA among them can occur at any place in the world. So why do so many of them seem to come from Asia? For viruses related to birds and other farm animals, part of the reason may be related to differences in farming around the world. In Europe and North America, poultry are generally raised in large farms. In much of the rural parts of Asia, though, most households have some chickens, ducks, or other birds that provide eggs and meat. Therefore, a much larger part of the population has close contact with domestic birds. Another reason that Asia is often a source of flu viruses may be even more basic. A very large percentage of the world’s population lives in Asia. That means there are a lot more people who could be the original host to a mutated virus.
How do vaccines prevent disease?
Smallpox is a devastating disease. During the eighteenth century, it killed about 400,000 people each year in Europe alone, and left many of its survivors disfigured or blind. Worldwide, hundreds of millions of people have died from smallpox infections. In 1796, Edward Jenner discovered that people who had contracted a related but much milder disease, cowpox, tended to be immune to smallpox. He used this observation to develop a vaccine to protect against smallpox infection. In 1979, smallpox vaccination finally reached enough of the world’s population that the disease was declared to be extinct. How do vaccines work?
"Diseases can rarely be eliminated through early diagnosis or good treatment, but prevention can eliminate disease."
When you catch a disease, from a virus or bacterium, your immune system produces antibodies to fight the disease organism. After you recover, your body remembers how to make the antibodies for that particular disease. If you are exposed to the organism again, the system kicks in, produces the right antibodies, and wipes out the invader before it can become a problem. That’s why many diseases, such as chickenpox, generally only occur once during your lifetime. In the past, these diseases were known as childhood diseases because most people contracted them early in life and were then immune to the disease.
Definition
An antibody is a protein used by the immune system to identify and disable a specific bacterium or virus. Antibodies are produced by white blood cells. The general structure of all antibodies is similar, but there are differences in small regions of the molecule that allow millions of antibodies to exist, each of which is matched to a specific target.
Vaccines are a way to teach the immune system to produce the necessary antibodies without ever having had to fight an actual infection. There are several ways to do this. The smallpox vaccine exposed people to organisms that could cause a similar disease, whose symptoms were much milder. Even if the person contracted the disease, it did not create the problems of a smallpox infection. The organisms were similar enough, though, that the antibodies designed to attack the vaccine also worked against the smallpox virus. Some vaccines are produced by weakening the disease organism so that it cannot reproduce rapidly and cause a severe infection. The immune system responds to the foreign organism and designs antibodies to fight it.
Vaccines can also be produced by killing bacteria or deactivating viruses with chemicals or radiation. These organisms are now harmless and they can be injected into the body without any danger of causing a disease. Their presence can, however, cause the body to fight them as if they were living organisms, and design antibodies to destroy them.
Can sugar pills really stop pain?
When researchers test a new drug to determine its effectiveness, they need to compare the results with those for people who do not take the drug. Usually, though, they have to also compare to people who think they are taking the drug but are not actually doing so. Doctors have known for a long time that it is possible to treat some conditions just by convincing the patients that they are receiving an effective treatment. One way to do this is to give a pill that looks like the real drug but contains no medication. Is it really possible for these "sugar pills" to stop pain and cure diseases?
Research has shown that, in some circumstances, a fake treatment, called a placebo, can be as effective as real medicines. For example, 30 to 40 percent of patients with conditions ranging from high blood pressure to arthritis and even Parkinson’s show improvement after taking placebo pills. Fake surgery, in which small incisions were made on patients’ knees, exhibited the same results as actual arthroscopic surgery in one study of arthritis treatments. How can a placebo have this kind of effect?
No one really knows exactly what happens when a placebo has a positive medical effect, but it appears to tap into a built-in healing power of the brain. For example, your brain can make chemicals that are similar in their effects to morphine. Studies have shown that, under certain conditions, these chemicals are released by the brain if the patient believes that a pill will relieve pain. The pain relief is real, not imagined, because the brain chemicals have the same effect as pain killers that are known to work.
Fast Facts
Researchers compare effectiveness of a proposed drug with a placebo in order to determine how effective the medicine really is. If it is not more effective than the placebo, it has no real effect, even if it is better than no treatment at all. In one study of the effectiveness of aspirin in preventing heart attacks, the aspirin was so much better than the placebo that the study was stopped long before the five-year test was completed. The effectiveness was so clear that doctors began to recommend regular doses of aspirin for all at-risk patients.
Placebos do not always work, though. Unlike those conditions where the brain apparently has untapped resources, diseases such as cancer do not respond to placebos. Even so, there is an amazing range of problems which can apparently be treated by giving your brain permission to just go do its thing.
Why do joints get sore and red when you have arthritis?
Arthritis can be very painful and cause joints to swell, feel hot, and turn red. These symptoms, known as inflammation, are similar to the symptoms of some infections, even though arthritis is not caused by bacteria or viruses. What causes inflammation in joints?
In many cases, the symptoms of arthritis are similar to those of infection, and in fact have the same cause. Inflammation is the process that your body uses to protect itself from an invasion by bacteria and viruses. The immune system sends in white blood cells and other tools to destroy the invaders. In addition to the white cells, a number of proteins and other chemicals are sent to the site to provide protection.
In some diseases, such as bursitis and some forms of arthritis, the immune system goes into defense mode when there are no foreign cells around. When this happens, the immune system attacks the body’s own tissues, treating them as if they were an invasion themselves. This type of inflammation is known as an autoimmune response.
Arthritis is not a disease of the elderly. Although many older people do suffer from arthritis and from joints that have been damaged by the disease, people of any age can have arthritis. Juvenile arthritis is a joint inflammation that strikes children under the age of 16.
The symptoms of inflammation caused by an autoimmune response include redness and swelling as extra blood is pumped into the region. This swelling, along with action by some of the immune system chemicals, causes stiffness in the joint and stimulates nerves, creating painful sensations. If the inflammation is not reduced, the increase of cells and other substances in the joint can damage the joint itself by causing swelling in the joint lining. The swelling can also damage cartilage that provides padding between bones.
Does the color of a bruise indicate how bad it is?
When you bang you arm sharply against a cabinet or bang your shin against a chair, you often get a bruise. It may appear to be a bit of reddening at first, but over time bruises can take on many different colors. Does the color of a bruise indicate anything about its severity?
Sometimes a bruise does not go away on its own. Instead of breaking down the trapped blood, the body walls it off, forming a firm, sometimes painful, swelling between the skin and the muscle. This swelling, called a hematoma, may need to be drained by a doctor before i t goes away.
A bruise occurs when small blood vessels under the skin rupture or tear. The blood that flows out of them becomes trapped in a pool under the skin and can’t return to normal circulation. In general, bruises are not a major health problem, even though they are unsightly, and they tend to go away on their own. Bruises are usually caused by a bump or fall. Some people, especially older adults, bruise very easily, so they may not even notice or remember what caused the bruise.
The colors of a bruise do not indicate how bad it is, but instead are more closely related to its age. In the first few minutes after you get a bruise, it will generally be red or pink as blood collects beneath the skin. Within a few hours, the layer of blood takes on the typical black and blue shades.
Over the next two to four weeks, the bruise slowly heals. As it does, the body breaks the trapped blood down into its components, which are then recycled. Various compounds in the blood have different colors, as do the compounds into which it breaks down. As the bruise heals, various components and breakdown products show through the skin. In general, the dark black, blue, or purple of a new bruise gradually fades to be replaced by a succession of color. Violet gives way to green or dark yellow, which gradually fades to light yellow and then disappears.
Why is it so hard to find a cure for the common cold?
A few centuries ago, people were pretty much at the mercy of nature when it came to disease. No one knew that many diseases were caused by microorganisms. There were no antibiotics to cure an infection and no vaccinations to prevent one. Many of the terrible infectious diseases of the past can be controlled fairly well today. Most of the worst can be prevented by immunization and hygiene. When an infection does occur, it can often be treated with antibiotics. One curse remains untouched, though—the common cold. Why can’t we find a way to prevent or cure colds?
Many virus infections are prevented by vaccination but, unfortunately, that doesn’t work for the cold. As it turns out, there is not just one common cold—there are hundreds of common colds. A whole series of viruses, known as rhinoviruses, cause the symptoms that we know as a cold. You probably have a natural immunity to some of them, thanks to your immune system’s reaction to previous colds, but there are more to come. Beyond that, due to mutations of the existing viruses, there are probably new cold viruses coming out all the time.
If you can’t stop the virus, how about treating the cold to cure it faster? There have been quite a few proposed cures for the cold, including nose sprays, zinc, and vitamin C. Unfortunately, none of them has held up too well in research to determine their effectiveness.
Actually, most of the symptoms of a cold are not caused by the virus anyway. Sneezing, a runny nose, fever, and congestion are caused by your immune system’s efforts to fight the virus. Inflammation in your sinuses does not really do too much to get rid of the cold viruses, but your body includes it.
For now, your best bet for preventing a cold is frequent hand washing to prevent transferring viruses to your mouth and nose. The best treatment is plenty of fluids and rest. The traditional chicken soup is probably as good as anything else you can come up with. It doesn’t fight the virus either, but it tastes better than most of the alternatives.
"When are we going to say cancer is cured? I’m not sure when that will happen, if that will happen because cancer is a very slippery disease and it involves a vast number of cells in the body and those cells are continually mutating."
