The editorial board of the Harvard Health Letter recently released the top 10 health stories of 2009. Each year, editors of the publication ask doctors on its editorial board to select ten fascinating health and medical stories and explain why the items are newsworthy.

Listed below are the top stories and the editorial board’s explanations, in part, as to why the stories made the list.

1. No panic about this pandemic: Most of the news about this year’s H1N1 “swine flu” pandemic has been reassuring. Plenty of information has been made available, and health officials gave us simple, concrete things to do to protect ourselves. A vaccine was developed and put into production, although shortages are a serious concern. We have months of flu season ahead of us and much could go wrong, but early indications show that this pandemic will stay manageable.

2. Health care reform: Half a loaf: Expanding coverage will be no small feat, but it's a breeze, politically, compared with reining in spending. Chances are that 2009's reforms won't do enough on the cost side, and there's no consensus on how to proceed. Technology (new drugs, new tests) has been the driving force behind health care spending for decades. Some economists see technology's effects as easing up and that it could even save money in the future.

3. Bad fat, good fat: White fat cells store fat, and most of the fat in our bodies — visceral and subcutaneous— is white fat. But there are also brown fat cells that actually burn fat. We have brown fat as newborns to help with the regulation of body heat, but it's long been believed that it soon disappears.

4. Curbing the doctor-industry relationship: Companies — particularly drug manufacturers — spend billions each year promoting their wares to doctors. In 2009, a wave of new rules and regulations went into effect to slow down the flow of gifts (all those logo-emblazoned pads and pens), free meals, and payments to physicians. The changes were made in response to criticism that industry largesse was creating conflicts of interest. Too often, there was a risk that the doctor-industry relationship would taint the doctor-patient one.

5. At last, maybe an alternative to warfarin: By blocking vitamin K, warfarin (Coumadin) reduces the risk for blood clots and, in turn, for stroke and other life-threatening, clot-related disorders.

But warfarin interacts with dozens of drugs, herbs, and foods. Frequent blood tests are often necessary to make sure the blood's clotting capacity is in a safe range. Patients and their doctors have accepted these drawbacks for lack of a good alternative. But in 2009, one might have been found. Dabigatran, which is already approved in Europe for limited purposes, acts directly on thrombin, one of the key players in the formation of blood clots. No blood monitoring is needed, and because of the way the drug is metabolized, there are far fewer interactions to worry about.

The FDA is expected to approve dabigatran in 2010. It will undoubtedly be more expensive than warfarin, although blood tests won't be needed, so that might help offset some of the additional expense. People who don't need frequent blood tests and dose adjustments may be better off sticking with the old standby, warfarin, but the convenience and efficacy of dabigatran is likely to be a real advantage for many patients.

6. These micros are major: Messenger RNA reads the DNA of our genes and uses that code to assemble proteins, the building blocks of all forms of life. In the mid-1990s, researchers discovered small bits of RNA, now known as microRNA, that attach to the messenger version and switch it off, so the protein doesn't get made. 

Already microRNAs are playing an important role in helping cancer doctors make more accurate diagnoses and prognoses and choose more effective treatments. For example, in 2009, researchers reported that liver cancer patients whose tumors had lower levels of a particular microRNA, called miR-26, had a much worse prognosis, but also a better response to one kind of treatment.

7. Blood sugar levels: Seeking the sweet spot: Several years ago, Belgian researchers published results showing that the sickest of the sick — patients in intensive care units  — fared far better if their blood sugar levels were very tightly controlled.

That study was influential, partly because it fit so nicely with the conventional wisdom about the perils of sugary blood. Guidelines were revised, so tight blood sugar control, accomplished with intravenous infusions of insulin, became a priority in ICUs throughout the country.

Now it's looking like those guidelines may need to be revised again. Results from a large randomized trial (too cutely called the NICE-SUGAR trial) showed that the death rate for tightly controlled patients was higher than it was for patients controlled to more conventional levels. The difference was 2.6 percentage points (27.5% vs. 24.9%), which may not seem like much but translates into many deaths given the number of ICU patients.

Doctors aren’t going to completely abandon controlling the blood sugar of ICU patients. But to paraphrase one commentator on the trial results, they’ll now be looking for the “sweet spot” between control that is too tight and too loose.

8. CRP: Ready to make an entrance?: Late in 2008, results from the industry-funded JUPITER trial showed that people with normal LDL cholesterol levels (less than 130 mg/dL) but relatively high CRP levels (2 mg/L or higher) could cut their risk of having a heart attack or stroke in half by taking a high dose (20 mg) of a powerful statin drug, rosuvastatin (Crestor).

CRP stands for C-reactive protein, a chemical in the blood that's a good indicator of inflammation. Statin drugs are taken primarily to lower LDL levels, but this was added proof that they also calm inflammation. That first round of JUPITER results made a big splash, but it left room for debate about how CRP testing and lowering should fit into cardiovascular care.

9. Screens with holes: Fresh doubts emerged about the wisdom of the current screening tests for breast and prostate cancers. A provocative analysis in The Journal of the American Medical Association came to the conclusion that the past 20 years of screening mammography for breast cancer and prostate-specific antigen testing for prostate cancer has led to detection and treatment of many cancers that pose minimal risk while achieving only modest reductions in the number of more advanced cases.

The American Cancer Society was sticking to its screening recommendations: women ages 40 and older should have annual mammograms, and men should discuss the pros and cons of prostate cancer screening with their doctors. But the group was reportedly working on public statements that would make people more aware of the pitfalls of screening.

10. Do your friends make you fat?: We gain weight because we don't eat the right foods and don't exercise enough to burn off the calories. But a new wave of research is showing that the causation of weight gain and a variety of other health-related behaviors has a social dimension, spreading through social networks as if they were contagious. Social networks are the vast webs of relationships we find ourselves in: friends and relatives; their friends and relatives, the friends and relatives of those friends and relatives, and so on.