A. What is osteoporosis?
Osteoporosis is a condition that causes thinning and weakening of normal bone. The definition of osteoporosis is a decrease of the density of bone mass. When this occurs, a patient with osteoporosis will have weaker bones and have a higher risk of bone fracture. Osteoporosis is not arthritis, which leads to problems within joints due to cartilage wear. Instead, osteoporosis is a problem of the bone, and its ability to adequately support the weight of your body. There are two main categories of osteoporosis, Type I and Type II.
Type I osteoporosis occurs only in post-menopausal women, and is due to estrogen deficiency. Type II osteoporosis occurs in both men and women (about two times more frequently in women), and is due to aging, and calcium deficiency over many years.
B. What causes osteoporosis?
As people age, the amount of bone in their body steadily decreases. Women are especially prone to developing thin bone because they don't develop as much bone while younger, and the rate of bone loss in women is greater than men. Because of this, age and gender are the most important risk factors for developing osteoporosis. Both men and women achieve their "peak bone mass" in the third decade of life. After that time, bone mass gradually, but steadily decreases. In pregnant and l
From Jonathan Cluett, M.D.,
Your Guide to Orthopedics.
How Does Pregnancy or Breastfeeding Affect the Risk of Osteoporosis?
A Woman’s Body Can Conserve Calcium
With such substantial demands on calcium during pregnancy and breastfeeding, researchers have investigated how having children might affect a woman’s risk of osteoporosis later in life. Fortunately, when a woman is pregnant, her body becomes more efficient at absorbing calcium from foods and her kidneys adapt by decreasing calcium losses in the urine.
Even with these adjustments, there is typically some bone loss during the last months of pregnancy. During breastfeeding, additional bone loss occurs, even with a high calcium intake. After weaning, bones can increase their uptake of calcium and rapidly restore calcium back to pre-pregnant levels if adequate calcium is present in the diet.
In the vast majority of normal healthy women, pregnancy and breastfeeding a baby results in a temporary loss of calcium from bones that is rapidly replenished after breastfeeding is finished.
Consequently, there is typically no effect on the long-term risk of osteoporosis.
Some Rare Problems for Bones
Although it is uncommon, some women have experienced low bone density and bone fractures during or shortly after pregnancy or during breastfeeding. Little is known about the causes of these rare occurrences, but they may be related to a woman having low bone density at the start of pregnancy. If bone density is too low, her bones may be unable to tolerate the normal temporary losses of calcium that occur. Researchers also think that unusual hormone fluctuations can be involved in some cases.
An old adage says that a woman should expect to lose a tooth for every child she has. If calcium intake is limited, there may be a touch of truth to this. A study published in the January 2007 issue of the Journal of Periodontology reported that female rats were more likely to lose supportive bone around the teeth when they were nursing their young and consuming a lower calcium diet. It makes sense to take a hint from the rats and keep up the calcium in your diet during breastfeeding.
Pregnant Teens causes Osteoporosis?
A pregnant teenager has high calcium needs for her own skeletal development. Consequently, there is some concern that the demands of fetal development could compromise the accumulation of peak bone mass for the teen mother. This concern is controversial, but provides extra reasons to encourage overall good nutrition and adequate calcium intake.
The Bottom Line
Bone density and fracture incidence are about the same in women who have had many children and those who have never been pregnant. A woman’s bones are well designed to deal with the demands of pregnancy as long as her diet provides an adequate supply of all nutrients.
Sources
Bone Health and Osteoporosis: A Report of the Surgeon General. (2004), U.S. Department of Health and Human Services, Public Health Service, Office of the Surgeon General. (Report)
Kovacs, Christopher S. “Calcium and Bone Metabolism During Pregnancy and Lactation.” Journal of Mammary Gland Biology and Neoplasia 10 (2005): 105-18. (Article Abstract)
Shoji, Kanako, et al. “Effects of Lactation on Alveolar Bone Loss in Experimental Periodontitis.” Journal of Periodontology (2007): 152-56. (Article Abstract)
Genetics and Race Play Important Roles
Many things affect your odds of developing osteoporosis. But your genetic and racial background can be significant risk factors. Osteoporosis does run in families, so if your family has a history of the condition, it is even more important for you to take steps now to have healthy bones throughout your life.
Scientists Narrowing in on Genetic Testing
Scientists are steadily gaining an understanding of which genes affect bones. A day will come when genetic testing will be able to rank an individual’s risk for osteoporosis. It may not be too far in the future. But, even if you knew that your risk of osteoporosis is low, it is still worth it to keep up activities that promote bone health -- such as exercise and eating calcium-rich foods -- because those things often reduce the risks of other diseases, as well.
Does Race Affect the Risk of Osteoporosis?
Although there are racial differences, the disease occurs in all racial groups. However, generally, whites have a greater risk of bone fracture than Asians and Asians have a greater risk than blacks.
Making racial comparisons is complicated because people of different races generally differ from each other by more than just their genes. Besides the genetic differences, they may have very different diet, lifestyle, and environmental factors. For this reason, studies that investigate the effects of diet and exercise on bone health must compare people of similar racial makeup for the study conclusions to be valid.
For example, I have seen faulty claims that since whites have the highest incidence of osteoporosis and consume more milk products than other races, it proves that milk is not good for your bones. The poor logic of this statement was well illustrated by a study that was part of a large study conducted by T. Colin Campbell and colleagues from Cornell University. His group measured the bone mineral density (BMD) of morethan 800 Chinese women from five different counties in China. They found that the women with the greatest BMD resided in a pastoral district where milk was a common part of the diet. Their milk consumption resulted in significantly greater consumption of calcium, phosphorus, and protein. So, with all things being genetically similar, increased intake of these nutrients translated into better bones.
The Bottom Line
Regardless of your family and genetic risk, it is still beneficial to to maintain healthy behaviors that are known to reduce the risk of osteoporosis, such as lifting weights and eating adequate amounts of calcium-rich foods.
Sources
Huang, Qing-Yang and Annie Wai Chee Kung. “Genetics of osteoporosis.” Molecular Genetics and Metabolism 88 (2006): 295-306.
Hu, Ji-Fan, Xi-He Zhao, Jian-Bin Jia, Banoo Parpia, and T. Collin Campbell. “Dietary calcium and bone density among middle-aged and elderly women in China.” American Journal of Clinical Nutrition 58 (1993): 219-27.
Osteoporosis - Overview and Tips On Maintaining Bone Strength
Osteoporosis is a disease characterized by progressive loss of bone density. This results in thinning of bone tissue making one more susceptible to fractures, or broken bones. Although the incidence of osteoporosis is greater in women, men are also affected. Over ten million individuals in the United States today are affected by osteoporosis. It is a disease that is responsible for greater than 1.5 million fractures annually, making it a significant health care issue.
Osteoporosis occurs when the body fails to produce enough new bone or when too much bone is reabsorbed by the body. Throughout life, new bone is formed and old bone is reabsorbed. During infancy, childhood, and adolescence new bone is developed faster than old bone is removed. As a result, bone strength is maintained and may also become denser.
This process occurs until approximately age thirty. At this point peak bone mass is achieved. After this stage, bone re-absorption occurs in excess of bone formation resulting in weaker bone tissue.
Various risk factors are associated with the development of osteoporosis. These can be categorized into modifiable and non modifiable factors. Non modifiable risk factors include gender, ethnicity, body type, age, and past family history. Women are more susceptible to developing osteoporosis than men as are the elderly versus the young. Small “thin boned” body types are more at risk than larger “big boned” types. Caucasians and Asians are also at higher risk for developing osteoporosis than other ethnicities. Modifiable risk factors include inactive lifestyles, cigarette smoking, diets low in calcium and vitamin D, and low estrogen levels such that occur after menopause.
There are multiple ways to prevent the development of osteoporosis. Having a diet high in calcium and vitamin D is one important preventative measure. Calcium is important to maintain bone strength, however vitamin D plays a role in the absorption of calcium thus both are needed. Weight bearing exercises are another way to assist in maintaining strong bones. Bone tissue responds to the forces placed on them during exercise by becoming stronger. Lastly, avoiding cigarette smoking and alcohol consumption is one more way to prevent the onset of osteoporosis.
In fact, all nutritional treatments for osteoporosis and bone health include calcium and vitamin D, but they also include other elements like ground flax seeds, ipraflavone, vitamin K, natural hormones, reduction of smoking, caffeine, and alcohol, and just as important is the use of resistive exercise to increase bone strength.
Prevention Easier than Treatment for Osteoporosis
It is much easier to build healthy bones while we are young, than try to repair them when we are old. After the age of 30, it becomes increasingly difficult to build new bone, so the younger you start, the better:
- You should get at least 1200 milligrams of calcium per day from your diet or supplements. Studies show that the calcium from dairy products is the most absorbable form of dietary calcium, however you can also get calcium from anchovies, salmon (with bones), and calcium-fortified foods. If you don’t get enough calcium from your diet, take a calcium supplement. Other minerals like magnesium, and boron are important for bone health too. If you aren't sure if you need more calcium, take this screening test.
- Don’t Smoke. There are so many reasons not to smoke, and this is just another one. Smoking leads to an increase in the risk of bone fractures. If you smoke, you need to quit. If you don’t smoke, don’t start.
- Watch the caffeine. Caffeine may be linked to calcium loss from bones, so limit your intake of caffeinated beverages.
- Get out in the sun. Your body needs vitamin D to properly absorb calcium. Your body makes vitamin D from sun exposure. You don’t need to be a sun-worshipper; just a few minutes a day is enough. If you live in the northern latitudes, you might want to add vitamin D as a supplement in the winter months.
- Get some exercise. For kids, this is easy. Keep them active and they will build strong bones. As an adult, you need some resistive exercise, like weight lifting to put stress on the bones. This type of stress is good stress because it signals the bones to keep the much-needed calcium and other minerals in your bones.
Why Would Cola-Type Sodas Affect Bones?
It's not known precisely why soda-like drinks were linked to higher bone loss in women in this study, and the authors note that more research is needed. But other studies have proposed that people who drink plenty of sodas are likely to drink fewer calcium-containing beverages like milk. However, this study did not find this to be the case.
Two components found in cola -- but not in most other soda flavors -- are phosphoric acid and caffeine. Again, it's unclear if these two chemicals are the culprits.
The phosphorus part of phosphoric acid is a major component of bone mineral content, along with calcium. However, if phosphorus content of the diet is too high compared to calcium, it can alter hormone levels in a way that could increase bone loss. This should not be a problem if calcium intake is adequate.
Furthermore, caffeine can cause a very small reduction in calcium absorption. Some studies reported that caffeine also increases calcium loss in the urine, however this was later shown to be untrue when evaluated over longer periods of time. Bone health researcher Dr. Robert Heaney, professor of medicine at Creighton University in Omaha, Neb., put the caffeine issue into perspective, saying, “...the solution is not to decrease the caffeine intake of the Western world, but to provide adequate sources and intakes of calcium.”
Is Carbonation of Beverages Bad for Bones?
Carbonation (the addition of carbon dioxide gas to beverages) does not appear to have any effect on bone health. This is not surprising, since the body produces large amounts of carbon dioxide and is very efficient at releasing it in expired air. The amount of carbon dioxide in a carbonated beverage is rather minor compared to the amounts that the body produces.
Is Fructose in Soft Drinks Bad for Bones?
Some studies have indicated that high intake of fructose (from high fructose corn syrup) and other sugars can temporarily increase calcium loss in the urine. However, fructose does not affect total calcium loss when evaluated over a 24-hour period. So, as long as overall calcium intake is adequate, fructose is unlikely to be a significant factor.
To Drink or Not To Drink?
Therefore, the question is, “To drink or not to drink soda?” It is unlikely that sodas have a significant impact on bones because of their ingredients. Any harm to bone health is most likely due to what sodas do not contain: important bone minerals like calcium.
Non-cola sodas do not appear to have any negative effect on bones – especially if they are diet sodas. The cola-type sodas generally contain caffeine that temporarily increases calcium loss in the urine, but has no effect on 24 hour losses.
Keeping adequately hydrated is an important component of good nutrition for just about every function of the body.
If you are the type of person who just doesn’t like to drink enough water, adding a few diet sodas in your daily diet is unlikely to have negative effects on your bones. However, this assumes that the sodas are not displacing an adequate intake of foods, drinks, and/or dietary supplements that provide all the needed bone nutrients.
Sources :
Heaney, Robert P. “Effects of Caffeine on Bone and the Calcium Economy.” Food and Chemical Toxicology 40 (2002): 1263-70.
Heaney, Robert P. and Karen Rafferty. “Carbonated Beverages and Urinary Calcium Excretion.” American Journal of Clinical Nutrition 74 (2001): 343 - 347.
Tucker, Katherine L., et al. "Colas, but not Other Carbonated Beverages, Are Associated with Low Bone Mineral Density in Older Women: The Framingham Osteoporosis Study." American Journal of Clinical Nutrition 84 (2006): 936 - 942.
Milne, David B. and Forrest H. Nielsen. "The Interaction Between Dietary Fructose and Magnesium Adversely Affects Macromineral Homeostasis in Men." Journal of the American College of Nutrition 19 (2000): 31-7.
Bones Need To Get Enough Calcium
Providing your bones with enough calcium each day is one of the major components of a bone health regimen. For each day that you don’t absorb enough calcium to meet your needs, there is a net loss of calcium from your bones. If you fail to meet your needs day after day, there will be a steady decline in bone density and your risk of osteoporosis increases over time.
How Calcium Gets To the Bones
Getting calcium from your food to your bones requires a series of steps that involve digestion of food and freeing calcium from various food components that bind it. If the calcium remains bound up, it never gets into the body. The calcium just passes through the intestinal tract and your bones never see it.
When calcium can break free from other components in food, it has a good chance of being taken up (absorbed) by the cells along the intestinal tract. These intestinal cells can then release the calcium into the blood. Typically, about 30 percent of the calcium in food is taken up into the blood. However, the amount of calcium absorbed depends on the type of food consumed. The amount of calcium absorbed from a food can range from about 5 to 50 percent of the quantity in the food.
How To Get Enough Calcium To Your Skeleton
Don’t ask, “How much calcium is in that food?” Ask, “How much calcium can I absorb from that food?” In the U.S., the recommended daily calcium intake for adults (age19 to 50 years) is 1000 mg. This recommendation is based on the assumption that people can absorb about 300 mg of calcium from a diet that contains 1000 mg of calcium. This recommendation also assumes that the diet is composed of foods common to the U.S. diet, including milk products. If 300 mg of calcium is absorbed from the daily diet, it is likely enough calcium to replace all the calcium lost from the body that day. Consequently, there would be no net loss of calcium from the bones.
What Makes a Food a Good Source of Calcium?
For a food to be labeled a “good source” of calcium, U.S. food labeling law requires the legal serving size to contain at least 100 mg of calcium. That’s one tenth of the total daily recommended calcium intake (adults 19 to 50). However, there is a better way to think about this that takes into account how much calcium you can ABSORB from a food.
Using available information about the amount of calcium that is absorbed from various foods (fractional absorption), it is possible to determine “good sources” of calcium based on the ABSORBABLE calcium you need each day. So, if you should absorb about 300 mg of calcium each day, a “good source” should provide 10 percent of that or 30 mg of ABSORBABLE calcium in a customarily consumed amount of the food.
The table below lists some good food sources of absorbable calcium and shows what percentage of the calcium is typically absorbed from each food.
Some Good Food Sources of Absorbable Calcium
| Type of Food & Amount | Calcium per Serving (mg) | Percent Absorbed | Amount Absorbed per Serving (mg) |
| Plain lowfat yogurt (1 cup) | 448 | 32 | 144 |
| Fruit flavor lofat yogurt (1 cup) | 338 | 32 | 108 |
| Milk, skim (1 cup) | 316 | 32 | 101 |
| Milk, 2% fat (1 cup) | 285 | 32 | 91 |
| Orange juice, calcium fortified (1 cup) | 300 | 25 | 75 |
| Cheese, mozzarella, part skim (1.5 ounces) | 310 | 32 | 100 |
| Soymilk, calcium fortified (1 cup) | 300 | 24 | 72 |
| Chinese Mustard Greens, cooked (0.5 cup) | 212 | 40 | 85 |
| Chinese Cabbage, cooked (0.5 cup) | 79 | 54 | 43 |
| Sardines, canned in oil (3 ounces) | 324 | 27 | 88 |
Source
Titchenal, C. Alan and Joannie Dobbs. “A system to assess the quality of food sources of calcium.” Journal of Food Composition and Analysis (in press, corrected proof)) Available online 7 September 2006.Getting Enough Calcium In
Choosing good calcium sources isn't as easy as it might seem.
Simple lists of the amount of calcium in foods can be misleading. Many factors can affect the amount of calcium the body can obtain from those foods.
Foods containing calcium that our bodies can absorb readily are considered to be highly bioavailable sources of calcium. Foods with compounds that interfere with calcium absorption are considered to have poor calcium bioavailability. For example, spinach is high in calcium, but only about five percent of that calcium can be absorbed due to a conflicting food component known as oxalate. Other foods with low calcium bioavailability are rhubarb, most beans, nuts, and seeds. These foods all contain calcium, but only limited amounts can make it to the bones.
For example, almonds are frequently listed as a food source of calcium. After all, one ounce of almonds contains 80 mg of calcium, about twice as much as one ounce of milk. But due to the limited absorption of calcium from almonds and their high calorie content, you need to consume about 1000 calories of almonds to absorb 100 mg of calcium. Instead, you could absorb this much calcium from 90 calories of non-fat milk or about 100 calories of calcium-fortified soy milk or orange juice.
Some foods are not predictable sources of calcium. A good example is tofu which is available in many different types and forms. The calcium in tofu is well absorbed, but you must check the nutrition label to see if the brand you buy contains a significant amount of calcium.
Milk is the classic high calcium food because it is a concentrated calcium source that is readily absorbed. Other good sources include some green vegetables and calcium fortified foods.
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