When medical researchers want to study a disease that affects human beings, they try to find an "animal model" of the disease. This means finding the same disease affecting a different species, especially a species that can easily be studied in a laboratory. At first, they hoped that they would find osteoporosis in monkeys. Like women, monkeys have a monthly menstrual cycle, and some monkeys eventually go through menopause. They even lose some of the calcium from their bones after menopause. Yet monkeys don't get osteoporosis after menopause, not even if they go through menopause early from having their ovaries removed.
So why don't monkeys get osteoporosis? An even better question is this: why is osteoporosis so rare in most of the world's populations? Why is it so common in places like the United States and Scandinavia? In particular, why is it common in the same populations that get heart disease?
Osteoporosis is largely dietary
More animal protein, more osteoporosis
If you want to see how common osteoporosis is in a population, look at the number of elderly women in that population who break a hip. This involves some complicated arithmetic, because you have to adjust for the number of elderly women in the population. But once you run those numbers, you get an amazing result. The more animal protein a population consumes, the higher its risk of osteoporosis is. Women who get their protein from plants instead of animals are much less likely to get osteoporosis. You can see this same relationship when you compare different countries with each other and when you study the eating habits of women within the same population. When you keep getting the same results, even when you ask the question in different ways, you can be confident that you've found the truth.
It's clear that a diet that's rich in animal protein causes osteoporosis. The hard part is figuring out why. Is there something particularly dangerous about animal protein? Or is there something beneficial about plant foods as a whole? Could the answer to both questions be yes?
The proteins in animal tissue tend to contain more of the sulfur-containing amino acids methionine and cysteine than do the proteins of plants. This means that your body produces more sulfuric acid (battery acid!) when it burns animal protein than when it burns plant protein. As a result, eating animal protein produces an excess acid load in the body. This acid load is called metabolic acidosis. To buffer all that excess acid, your body sometimes borrows some of the calcium from your bones. You will then end up losing a lot of calcium through your kidneys. This explains why people who eat a lot of animal protein are at increased risk for both bone loss and kidney stones. It also explains why monkeys, which are plant-eaters, are remarkably free from osteoporosis, even after menopause.
More fruit and vegetables, less osteoporosis
The more fruit and vegetables people eat, the healthier they tend to be. A low risk of osteoporosis is only one of the many benefits of eating fruits and vegetables.
There's less sulfur in plant proteins than in animal proteins. As a result, you'd get less metabolic acidosis if you get your protein from plants instead of animals. Even better, if you eat lots of vegetables and fruit, you'll neutralize the acid from the plant proteins. Vegetables and fruit contain natural antacids: not only do they contain alkaline minerals, such as potassium, magnesium, and calcium, they often contain organic acids that get broken down into water and bicarbonate (as in baking soda!). That's why most fruits and vegetables have a net alkalinizing effect on the blood and urine. (One exception is cranberries, which contain an organic acid that doesn't get broken down before it passes into the urine.)
Besides containing natural antacids, vegetables and fruits may contain other nutrients that are important for the health of the bones. Examples include vitamin K and trace minerals such as boron.
More calcium, more osteoporosis!!!
We know that eating animal protein causes an acid load that can rob our bones of calcium. Can we compensate for this problem by eating more calcium? Unfortunately, high calcium intakes seem to make the problem worse, not better.
Whenever I pick up a women's magazine these days, I see articles and advertisements urging me to eat more high-calcium dairy foods and to take calcium supplements, in the hopes of preventing osteoporosis. Yet when I look at the scientific research, I find that populations who eat low-calcium diets are less likely to get osteoporosis than populations who eat high-calcium diets. Extra calcium seems to make the problem worse, not better!
When I look at the scientific research, I find that it's practically impossible to find anyone who got sick from eating a plant-based diet that's low in calcium. The people who have trouble with calcium balance are the ones who are eating too much animal protein, and too much calcium!
The human body is actually very good at maintaining calcium balance on a relatively low-calcium, plant-based diet. People get into trouble when they eat lots of animal protein. They get into even more trouble when they also eat lots of calcium. That's because people who eat lots of calcium don't use calcium efficiently. If they did, they would either turn to stone or die of calcium poisoning. Unfortunately, their bodies get so used to wasting calcium that they forget how to store it correctly.
Mark Hegsted, who was a researcher at Harvard Medical School and one of the world's foremost experts on calcium in nutrition, warned us back in 1986 that osteoporosis is not due to calcium deficiency, and that in fact the populations that are susceptible to osteoporosis are the rich Western industrialized societies where people eat lots of animal protein and lots of calcium. Eleven years later, the Study of Osteoporotic Fractures showed that the women who were using calcium supplements were more likely to break a bone. The researchers couldn't rule out the possibility that the calcium supplements were actually making the problem worse!
What about bone mineral density (BMD)?
Women's magazines nowadays are filled with articles that urge women to get their bone mineral density tested, and to take prescription drugs to boost their bone mineral density. These articles leave out an important fact. Bone mineral density is just a measure of how white your bones look on an x-ray image. It doesn't tell you much about how strong your bones are. For example, a stick of chalk would look stark white on an x-ray image. So would chalk dust. Yet neither of those is very strong. Bone is harder than chalk dust and harder to break than chalk because the mineral crystals in bone are embedded in a tough matrix made of cartilage.
What really matters, when push comes to shove, is how strong the bones are. The bone mineral density measurements don't tell us the whole story. Unfortunately, many of the recommendations that are being made for the prevention or treatment of osteoporosis are based on how they affect bone mineral density, not on how they affect the risk of fracture. There is serious concern that some treatments that make the bones look better on an x-ray may also be making them more brittle, and more likely to break.
How to prevent osteoporosis
Back in 1986, Mark Hegsted warned us that the conventional advice for preventing osteoporosis might be making things worse, not better. Fortunately, there is some general advice that seems to be helpful.
Eat plants, not animals
When researchers from the World Health Organization studied the problem of osteoporosis, they came up with two different sets of recommendations: one for places like Europe and North America, where people eat a lot of animal protein and osteoporosis is common, and a different one for places like Asia and Africa, where people eat much less animal protein and osteoporosis is rare. In other words, you can put yourself in a much lower risk category for osteoporosis just by cutting the animal protein out of your diet. The more fruit and vegetables you eat, the healthier your bones and the rest of your body will be.
Go outside and play
The human body is designed for an active, outdoor lifestyle. Yet many of us today live as if we were designed to be cave-dwelling slugs. Our health suffers as a result. Our muscles and bones deteriorate from lack of use, and we might end up with a deficiency of vitamin D.
Everyone knows that exercise makes your muscles stronger, but they might not realize that it also helps to make the bones stronger. By putting stress on the bones, exercise helps to stimulate the bone-remodeling process. This helps to rejuvenate the bones, and to strengthen them where necessary. Exercise also helps improve balance, flexibility, and coordination, so that people are less likely to fall and injure themselves. This improvement in general fitness can decrease the risk that someone with osteoporosis will fall and break a hip.
Spending some time outdoors can also ensure that you will get enough vitamin D to have strong bones and a healthy immune system. Vitamin D is actually a powerful hormone that is produced in your skin when the skin is exposed to the ultraviolet light in bright sunshine. People who avoid sunshine, or who use too much sunscreen, could end up with a deficiency of vitamin D.
In children, a severe deficiency of vitamin D causes a deformity called rickets. Vitamin D deficiency during gestation and early childhood might also increase the risk of autism. In adults, a severe deficiency of vitamin D can cause a bone softening called osteomalacia. It can also produce a painful syndrome that mimics fibromyalgia.
Light-skinned people at the latitude of Boston, Massachusetts, can generally get enough vitamin D from just getting a few minutes of noonday sunshine on their face and forearms during the spring, summer, and autumn. Dark-skinned people and those who live further north might want to have their doctor monitor their vitamin D levels.
Follow a healthy lifestyle
Although we think of osteoporosis as a disease of elderly women, it also occurs in elderly men. It can also occur in younger people, often as a result of a hormonal imbalance or from the use of cortisone-like drugs for the treatment of various diseases. Fortunately, you can reduce your risk of those same diseases by following the same lifestyle tips that help to prevent osteoporosis:
- Eat plants, not animals
- Go outside and play
A low-fat, plant-based diet is the first line of defense against many kinds of chronic degenerative disease. You might be able to reduce your risk of osteoporosis even further by doing the following:
- Don't smoke
- Don't eat too much salt
- Limit the intake of alcohol and caffeine
- Limit the intake of cola beverages, which contain phosphoric acid
The first step in managing any disease is to remove the cause. If you already have a diagnosis of osteoporosis, your first step in managing it will be to correct your diet, so as not to make the problem any worse. You and your doctor will also have to weigh the risks and benefits of the various available treatments.