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‘Good’ Cholesterol May Not Be So Great After All

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Bad news for good cholesterol: A Danish study published in European Heart Journal finds that people with extremely high high-density lipoprotein (HDL, often called “good” cholesterol) levels face a higher, not lower, risk of death.

Cholesterol as a substance is neither good nor bad, but an important part of our body chemistry. Like most things, in moderation, it's fine; the health risks set in once our levels get out of whack. Scientists and doctors have long understood cholesterol as a sort of angel-on-one-shoulder, devil-on-the-other situation, in which low-density lipoprotein (LDL) is harmful and HDL is helpful. HDL mediates LDL's negative effects, which means that having more HDL is good.

Or at least that's what we thought.

Researchers pulled health information on 116,000 people from the Copenhagen City Heart Study and the Copenhagen General Population Study, then cross-checked it against death reports from the Danish Civil Registration System. They followed study subjects for six years, during which more than 10,500 people died. 

What they found surprised them. Extremely high levels of HDL were associated with significantly greater risks of death than normal levels—68 percent higher for women and a staggering 106 percent for men. Men with very high HDL (one step down from "extremely high") were 36 percent more likely to die.

"These results radically change the way we understand 'good' cholesterol. Doctors like myself have been used to congratulating patients who had a very high level of HDL in their blood. But we should no longer do so, as this study shows a dramatically higher mortality rate," co-author Børge Nordestgaard of the University of Copenhagen said in a statement.

Before we get too worried, it's worth noting that these extremely high HDL levels were incredibly rare, affecting only 0.4 percent of male participants and 0.3 percent of women. The researchers say these people were also more likely to share unusual genetic variants. It's possible that these genes and not the cholesterol are responsible for their higher mortality rates.

Some elements of our ideas about cholesterol still held true. People with extremely low HDL levels also faced an increased mortality risk.

The safest levels seemed to be right in the middle, at 1.9 mmol/L for men and 2.4 mmol/L for women. 

More research is needed, as this study focused exclusively on white Danish people and only looked at correlation, not causation. 

Still, Nordestgaard said, "It appears that we need to remove the focus from HDL as an important health indicator in research, at hospitals and at the general practitioner. These are the smallest lipoproteins in the blood, and perhaps we ought to examine some of the larger ones instead."

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Animals
Owning a Dog May Add Years to Your Life, Study Shows
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We've said that having a furry friend can reduce depression, promote better sleep, and encourage more exercise. Now, research has indicated that caring for a canine might actually extend your lifespan.

Previous studies have shown that dog owners have an innate sense of comfort and increased well-being. A new paper published in Scientific Reports and conducted by Uppsala University in Sweden looked at the health records of 3.4 million of the country's residents. These records typically include personal data like marital status and whether the individual owns a pet. Researchers got additional insight from a national dog registry providing ownership information. According to the study, those with a dog for a housemate were less likely to die from cardiovascular disease or any other cause during the study's 12-year duration.

The study included adults 40 to 80 years old, with a mean age of 57. Researchers found that dogs were a positive predictor in health, particularly among singles. Those who had one were 33 percent less likely to die early than those who did not. Authors didn't conclude the exact reason behind the correlation: It could be active people are more likely to own dogs, that dogs promoted more activity, or that psychological factors like lowered incidences of depression might bolster overall well-being. Either way, having a pooch in your life could mean living a longer one.

[h/t Bloomberg]

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Live Smarter
Not Sure About Your Tap Water? Here's How to Test for Contaminants
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In the wake of Flint, Michigan's water crisis, you may have begun to wonder: Is my tap water safe? How would I know? To put your mind at ease—or just to satisfy your scientific curiosity—you can find out exactly what's in your municipal water pretty easily, as Popular Science reports. Depending on where you live, it might even be free.

A new water quality test called Tap Score, launched on Kickstarter in June 2017, helps you test for the most common household water contaminants for $120 per kit. You just need to take a few samples, mail them to the lab, and you'll get the results back in 10 days, telling you about lead levels, copper and cadmium content, arsenic, and other common hazardous materials that can make their way into water via pipes or wells. If you're mostly worried about lead, you can get a $40 test that only tells you about the lead and copper content of your water.

In New York State, a free lead-testing program will send you a test kit on request that allows you to send off samples of your water to a state-certified lab for processing, no purchase required. A few weeks later, you'll get a letter with the results, telling you what kind of lead levels were found in your water. This option is great if you live in New York, but if your state doesn't offer free testing (or only offers it to specific locations, like schools), there are other budget-friendly ways to test, too.

While mailing samples of your water off to a certified lab is the most accurate way to test your water, you can do it entirely at home with inexpensive strip tests that will only set you back $10 to $15. These tests aren't as sensitive as lab versions, and they don't test for as many contaminants, but they can tell you roughly whether you should be concerned about high levels of toxic metals like lead. The strip tests will only give you positive or negative readings, though, whereas the EPA and other official agencies test for the concentration of contaminants (the parts-per-billion) to determine the safety of a water source. If you're truly concerned with what's in your water, you should probably stick to sending your samples off to a professional, since you'll get a more detailed report of the results from a lab than from a colored strip.

In the future, there will likely be an even quicker way to test for lead and other metals—one that hooks up to your smartphone. Gitanjali Rao, an 11-year-old from Colorado, won the 2017 Young Scientist Challenge by inventing Tethys, a faster lead-testing device than what's currently on the market. With Tethys, instead of waiting for a lab, you can get results instantly. It's not commercially available yet, though, so for now, we'll have to stick with mail-away options.

[h/t Popular Science]

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