| ||What Your Doctor Is Reading || |
Update From the Medical Journals: December 2010
December 31, 2010
By Mary Pickett, M.D.
Harvard Medical School
What's the latest news in the medical journals this month? Find out what your doctor is reading.
New Recommendations Made for Vitamin D and Calcium
An Institute of Medicine (IOM) panel has made new recommendations about how much vitamin D is best for health. The panel brings together independent scientists who advise the government on health issues. It's been 13 years since the guidelines were last updated.
Although most people are getting adequate vitamin D, the IOM panel stated that children, adolescent girls and many adults need supplements to meet the guidelines. The panel recommended increasing the "recommended daily allowance" (RDA), the amount we should get from food and supplements each day. The IOM published its report on November 30.
The new RDAs are based on age:
- Ages 1-70: 600 international units (IU)
- Ages 71 and older: 800 IU
People with a vitamin-D deficiency need higher-dose supplements.
The IOM also recommended new daily amounts for calcium:
- Ages 1-3: 700 milligrams (mg)
- Ages 4-8: 1,000 mg
- Ages 9-18: 1,300 mg
- Ages 19-70: 1,000 mg (for women over 50 the amount is 1,200 mg)
- Over age 70: 1,200 mg
Vitamin D has become a hot topic among health experts in recent years. Vitamin D is important for bone strength and muscle health. Low vitamin D causes muscle weakness, muscle aches and a higher risk for falling. Having a normal level of vitamin D helps to prevent infections and cancer. A recent study also showed that people who have vitamin D levels below 15 ng/mL (nanograms per milliliter) appear to have about twice the risk of having a heart or stroke, compared with people who have higher levels.
The report cautioned that we don't know how safe it is to take doses of vitamin D that exceed the RDA if you don't have a known deficiency. The report also advises that people who take supplements should not go overboard on their dosing. Too much vitamin D can definitely lead to health problems, such as kidney stones or high calcium levels. Very high calcium levels can cause abdominal symptoms and confusion.
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Yearly Screening Tests for Ovarian Cancer Are Not Very Helpful
Ovarian cancer is one of the most challenging cancers to treat. It can occur at a young age, compared to other cancers. About three out of four ovarian cancer cases are not found until the disease is in a later stage. What would happen if we asked women to have yearly screening tests for ovarian cancer? Would this help us identify ovarian cancer much earlier than we can now? If so, maybe more women could survive this cancer.
A new study reviewed the currently available screening tests for ovarian cancer, and predicted whether these tests could prevent deaths cancer if they were repeated on a yearly basis. The study found that the available tests are almost useless against this cancer.
The study was published online by the journal Cancer on December 13.
The two screening tests this study looked at are ultrasound and the CA-125 blood test. (High levels of the CA-125 protein can sometimes be a sign of cancer, including ovarian cancer. But the test is not very specific.)
Researchers created a computer model to show the growth of ovarian cancer. Some types grow faster and others more slowly, and the model accounted for this difference. Researchers estimated how many cancers could be detected with current screening tests, and at what stages. Researchers found that yearly screening tests are more likely to detect slow-growing cancers than fast-growing ones. Overall, having screening tests every year would only reduce deaths from ovarian cancer by about 11%. This is too small a number to make the cost of testing worthwhile for women at average risk.
Women who have a family history of ovarian cancer or who carry a BRCA gene are at high risk for ovarian cancer. The most effective way to protect yourself against ovarian cancer, in this situation, is to have the ovaries surgically removed. The long-term use of birth control pills can cut the risk for this cancer in half. Having a tubal ligation (having your "tubes tied") also seems to lower the risk for ovarian cancer.
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HIV Drug Prevents Infection for People at High Risk
Daily use of two drugs that treat HIV can help prevent infection in people who practice risky sex, according to a new study. The study was published online by the New England Journal of Medicine November 23.
Regular condom use has been the preferred way to prevent the spread of HIV infection. But researchers decided to take a serious look at preventing infection with drugs. In the past, the cost of the medicines and side effects have discouraged experts from testing this approach as a way to prevent infection.
The study included nearly 2,500 men and transgender women who had sex with men. These participants were chosen because they were at high risk for HIV exposure. Many of the participants had risky drinking habits, traded sex for money, or reported frequent sex without condoms. Many of the participants had more than 1 sexual partner each week; more than 80% had unprotected sex in the last 6 months. At the start of the study, none of the participants were infected with HIV.
The people in the study were randomly divided into 2 groups of similar size. The participants in one group took the HIV combination treatment pill "Truvada" daily. (Truvada includes the HIV drugs emtricitabine and tenofovir.) The other group took a placebo pill. All of the participants received counseling and condoms. (They were advised to use condoms every time they had sex). The study lasted for almost 3 years. During that time, 64 men taking placebo pills and 36 men taking Truvada became infected.
Among those who took their pills at least half the time, the risk of getting HIV was cut in half. For those who took almost all of their medicine (90% of what was prescribed), the risk dropped by 73%.
For people who engage in risky sex, taking HIV medicine as a way to prevent HIV infection might be a reasonable addition to current prevention strategies. Long-term safety and cost issues still need to be worked out.
More News in Brief
- People With Abnormal Liver Tests Should Still Start Cholesterol Drugs. Statin drugs for cholesterol can cause liver changes, so most doctors do liver tests before starting a person on a statin drug. Some people avoid starting these cholesterol medicines if their liver tests are not normal. But an article published online by the Lancet on November 23 showed that people who have abnormal liver tests get even more protection against heart disease if they do treat their cholesterol. Most people who have mild liver test abnormalities, particularly those with a high level of the liver enzyme "ALT," have a condition called non-alcoholic fatty liver disease (NAFLD). Fatty liver disease is one way the body shows that it has an unhealthy pattern of metabolism. Fatty liver is associated with atherosclerosis (artery disease) and diabetes, conditions that cause an increased risk for heart disease and stroke. Researchers studied 437 patients with moderately abnormal liver tests. Half of them took a statin drug and the other half were not treated. Significant liver-related health problems occurred at the same rate in both groups. The study continued for 3 years. Liver tests (measured by ALT level) improved in the group that took statin drugs, probably from improvement in fatty liver. Liver tests got worse overall in the group that did not take statins. In this study, patients who got statin treatment had a 39% lower risk of having a heart attack or stroke compared with the placebo group. Bottom line: Statin drugs make sense for people who have mildly abnormal liver tests that could be related to fatty liver.
- Weights Plus Aerobics Is Best Way To Control Diabetes. A combination of resistance exercise (lifting weights) and aerobic exercise (brisk walking, biking, swimming or other aerobic exercise) work best for people with diabetes when it comes to blood sugar control. The Journal of the American Medical Association published a study of 262 people with type 2 diabetes. None of them had a regular exercise habit prior to the study. Participants were assigned to spend 140 minutes per week exercising. The study lasted 9 months. Forty-one percent of participants who did both weights and aerobic exercise saw significant improvements in their blood sugar. Many of them were able to reduce the amount of diabetes medicine that they took. Among the people who just did resistance training, 26% improved their blood sugar; 29% of the people who did aerobic exercise alone had this improvement.
- Possible Breakthrough Occurs in Alzheimer's Research. A study published December 9 in Science may give us a better understanding about the cause of Alzheimer's disease and dementia. The study focused on the protein beta-amyloid. Accumulation of beta-amyloid is a known sign of the disease. In the study, researchers measured beta-amyloid production in the brains of people who had Alzheimer's disease and people who did not. They also watched to see how quickly the protein was cleared out of the brains of people in both groups. They compared rates at which the brain produced and cleared the protein. The study was very small only 24 patients in all. But what researchers found was significant. Alzheimer's patients cleared the protein about 30% more slowly. This study will have a strong impact on other current Alzheimer's research, and may lead us towards an effective way to treat this disease.
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Mary Pickett, M.D. is an Associate professor at Oregon Health & Science University where she is a primary care doctor for adults. She supervises and educates residents in the field of Internal Medicine, for outpatient and hospital care. She is a Lecturer for Harvard Medical School and a Senior Medical Editor for Harvard Health Publications.