Preventing common diseases: Part 1 - osteoporosis

By Joseph Cannon and Christopher Theberge

What disease are college-aged individuals most concerned about? If you ask most, I doubt you will hear many people respond with osteoporosis. This disease, which mainly affects older individuals, relates to a weakening and thinning of bones due to a loss in calcium stores. Why should you be concerned if osteoporosis is a disease the effects mainly individuals over 50-years-old?

According to the National Institute of Health on Osteoporosis and Bone Related Disorders, in the U.S. today 10 million people are living with osteoporosis and another 18 million are at high risk due to low bone mass. Approximately one in every two women and one in every eight men will have an osteoporosis related fracture at some point in their life. Men are less susceptible to developing osteoporosis because they generally have larger bones and achieve greater peak bone mass than women. Women also lose more bone mass as a result of hormonal changes associated with menopause. Family history of osteoporosis increases ones risk of the disease and Caucasian and Asian women are more likely to develop osteoporosis compared to African-American and Hispanic women.

One of the most important ways to prevent osteoporosis is making sure that normal peak bone mass is achieved by about 20 years of age. Although peak bone mass is mainly attained during the third decade of life, the amount of bone formed during your 20s to 30s is relatively small.

Bones are constantly breaking down and reforming. These two processes parallel each other until approximately 30 years of age when natural bone loss begins. Therefore, bones become progressively weaker and less dense as you age. Bone loss through aging is inevitable; however there are several ways to alleviate the rate at which this occurs. Many decisions you make now will determine your osteoporosis risk later in life. Current nutrition and exercise habits are two dynamics you must pay close attention to.

Preventing osteoporosis through nutrition:

Studies have shown that teenage girls, adult women, and adults over 65 years of age have calcium intakes below the RDA. Why is this a concern?

About 99 percent of your body's calcium is found in teeth and bones. Adequate calcium consumption is crucial to ensure that your bones have enough of the building blocks for formation. Also, calcium levels in the blood are under tight control, which aims to maintain a steady calcium level. When calcium levels are low, with inadequate intake for example, your bones will release calcium to maintain that steady state. If calcium intake is consistently low, then your bones must continuously give up their calcium, instead of using it for its own development, resulting in lower bone mineral content, and hence lower density. Depending on your age, average calcium consumption should be between 1000 mg-1300 mg each day. Calcium supplementation is rarely warranted because it is very easy to meet your daily requirements with food.

Vitamin D is a fat soluble vitamin that is needed in adequate amounts to ensure that calcium is absorbed. There are two ways in which we get the vitamin. First, the sun can provide a way of processing the vitamin on the skin, which is followed by absorption into the body. Secondly, dietary intake can come from fortified milk, cod liver oil, and egg yolks, although in small amounts. Considering the region that we live in, conversion of vitamin D from the sun is not enough to provide adequate amounts, therefore dietary intake is needed. Interestingly, the major source of vitamin D in the American diet is from milk. Milk is also the major contributor of calcium. Therefore, it is to no surprise that inadequate calcium intake will also lead to inadequate vitamin D intakes. It is recommended that individuals receive about 400 IU - 800 IU of vitamin D each day through the diet.

Adequate calcium and vitamin D intake is easily achieved by drinking at least three glasses of milk, preferably skim, each day. Dairy products in general are excellent calcium foods, yet they are not the only way to meet your daily requirements. Canned fish products such as sardines provide ample amounts of calcium. Green leafy vegetables (i.e. Collard greens) are also calcium containing foods; however the presence of phytates and oxalates bind to calcium and limit the amount that is absorbed. Fortification of soy products, orange juice and cereals with calcium will greatly improve the calcium status of consumers.

Vitamin K is another fat-soluble vitamin necessary for normal bone health. One of its major functions is to aid in the formation of osteocalcin, a contributor to bone formation. Studies have related low vitamin K intakes with increased risk for osteoporosis. Vitamin K is synthesized by intestinal bacteria, yet the rate at which it is absorbed is not enough to maintain necessary levels in the body. Therefore vitamin K must be consumed through the diet. Dark green leafy vegetables, liver, alfalfa and kelp are all excellent sources.

High intakes of animal protein or sodium can increase the amount of calcium lost in the urine. Studies have related vegetarian diets with reduced urinary calcium loss compared to diets high in animal protein. Sodium by itself has the potential to increase the amount of calcium lost in the urine. Since Americans tend to have high protein diets, lowering your intake or substituting meat with beans or tofu can help to spare calcium. Replacing soda with milk, and not adding salt to your foods will also help.

Preventing Osteoporosis through exercise

Regular exercise aids in bone formation by adding mechanical stress to the bone and greatly increasing the amount of minerals deposited over time. Bone development is most effective when the activity is medium to high impact. Some of the best exercises to strengthen your bones include: running, weight training, and stop and go sports such as basketball, soccer and field hockey. The constant pounding impact will increase bone density, and improve balance and agility lessening the risks of falls and fractures.

For women there are additional factors to keep in mind regarding exercise, sports, and osteoporosis. The female athlete triad is a condition that often occurs in young females involved in endurance and weight-control sports (dancing and gymnastics). The triad consists of amenorrhea, disordered eating, and osteoporosis which all lead to a lessening of bone density. Amenorrhea occurs in female athletes when the menstrual cycle ceases because hormones become highly imbalanced. The imbalance often takes place when extreme exercise regimens and restricted calorie intake are present. Estrogen production is therefore reduced, and its important support in bone formation is lost. Disordered or irregular eating habits have a significant impact on bone density as well.

Many athletes feel stressed to maintain a certain figure to be competitive in their respective sport; but without adequate calories, nutrients, and minerals, bone deposition will not occur. When both of these conditions are present, density is greatly lowered and it is comparable to post-menopausal women. Risk of osteoporosis for these otherwise healthy athletes is increased.

Other Factors

In addition to exercise and nutrition other factors will influence how densely your bones form. Excessive use of drugs such as alcohol, caffeine and tobacco adversely affect bone deposition in many ways. Daily consumption of two to three ounces of hard alcohol or two to three beers per day may be damaging to the skeleton. Heavy drinkers have shown to have less dense bones and increased non-traumatic fractures then that of individuals who don't consume excess alcohol.

Caffeine, in high amounts, has the potential to impair calcium absorption, thereby reducing bone density over time. Although this may seem as a major problem, adding small amounts of milk to your coffee can offset this problem. This loss may also be accounted for because of excess caffeine in the diet and inadequate calcium.

Finally, smoking, in general, is bad for your body. In regard to osteoporosis, smoking inhibits calcium uptake to a degree, reduces the formation of new bone, and nicotine may have inhibitory effects on estrogen, which aids in bone formation in women. Moderate consumption, or in the case of smoking, abstaining all together from use is the best choice to aid in peak bone density formation.