Type I osteoporosis (postmenopausal osteoporosis) can be significantly influenced by several preventive measures. Most of these measures are in the hands of the individual and should be started as early in life as possible.
An individual’s peak bone mass is typically achieved by the age of 30. The amount of bone that is obtained at one’s peak, and how much is retained thereafter, is influenced by several factors, including:
Genetics and osteoporosis
It is important for individuals to know their genetic predisposition to osteoporosis. Genetics plays an important role—it is estimated that about 75% of an individual’s peak bone mass is influenced by genetics. There are genes that code for Vitamin D receptors and for estrogen receptors that both significantly affect peak bone mass. If one is genetically predisposed to osteoporosis, then exercise, diet and regular bone mass testing are even more important.
Exercise and osteoporosis
Weight bearing exercise (which refers to activity that one performs while on their feet that works the bones and muscles against gravity) and muscle contraction combined have been shown to effectively increase bone density in the spine. It is recommended that an individual perform 20 to 30 minutes of aerobic exercise 3 to 4 times weekly to increase bone mass.
In a study by Dalsky in 1988, jogging, walking, or stair climbing at 70-90% of maximum effort three times per week, along with 1,500 mg of calcium per day, increased bone density of the lumbar (lower) spine by 5% over 9 months. Exercises in a pool have not been shown to increase bone density.
A note of caution: for people with osteoporosis or low bone mass, care must be taken when exercising especially with regard to posture and body mechanics. Activities that require twisting of the spine or bending forward from the waist (such as conventional sit-ups or toe touches) may be dangerous. Individuals already diagnosed with osteopenia or osteoporosis should discuss their exercise program with their physician to avoid fractures.
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Diet and osteoporosis
Adequate calcium intake is critical in keeping bones strong, and it is estimated that approximately 70% of people do not regularly ingest adequate amounts of calcium or vitamin D. Vitamin D is also critical, as it helps ensure absorption and retention of calcium in the bones.
The recommended amounts of calcium and vitamin D for adults are as follows2:
- For pre-menopausal women 25-50 years old and post-menopausal women on estrogen replacement therapy, 1,000 milligrams of calcium per day with 400 i.u. of Vitamin D. 1,500 milligrams of calcium per day is recommended for pregnant or lactating women.
- For postmenopausal women less than age 65 not on estrogen replacement therapy, 1,500 milligrams of calcium per day is recommended along with 400-800 i.u. of Vitamin D.
- For men ages 25-65, 1,000 milligrams of calcium per day is recommended.
- For all people (women and men) over age 65, 1,500 milligrams of calcium per day.
Calcium can be found in many everyday foods. Examples of foods that contain calcium include: dairy products (e.g., milk, yogurt, cheese), dark green vegetables (e.g. spinach), grains, beans and some fish.
Additionally, there are a number of calcium supplements that are available. Calcium supplements have varying amounts of calcium, so it is important to speak to a pharmacist before taking calcium to make sure that the appropriate amount is being used.
Vitamin D comes from sunshine, fatty fish, liver, and fortified foods like milk, orange juice and cereals. Vitamin D supplements are also available.
In addition to adequate intake of calcium and Vitamin D, it has been shown that an overall balanced and healthy diet plays an important role in preventing osteoporosis. For example, diets that are high in protein and/or sodium increase the loss of calcium through the urine and contribute to decreased calcium availability.
It is important to note that over 2000 milligrams of calcium per day can be harmful to the kidneys and cause kidney stones. However, when calcium is taken in the recommended dose there is no increase in kidney stone formation. People with pre-existing kidney disease should consult their physician.
Bone density testing and medications to slow bone loss
A bone mineral density (BMD) test measures an individual’s bone density and compares it to the densities of other people. Not only does a BMD test indicate whether someone has a normal, low or osteoporotic bone density level, it also indicates if someone is at increased risk of sustaining a fracture. Some physicians recommend regular bone density testing (every 1-2 years) for all women over age 65 and postmenopausal women less than age 65 who have multiple risk factors for osteoporosis.
Depending on the bone density test and other examinations/diagnostic tests, an individual’s physician may prescribe medications in order to slow bone loss and stave off osteoporosis and osteoporotic fractures. See Osteoporosis Treatment for a discussion of the approved osteoporosis medications.