Tag Archives: senior citizens

Health, News

Elderly Persons! Your Vitamin D Level Better Be More Than 20 Ng/ml

2 Comments
This cactus illustrates the best way to get vitamin D: live in Mexico. (Photo: MvB)

Vitamin D! Do you have enough? The numbers have been squishy. At one point, it seemed likely that everyone in the U.S. was suffering from a “deficiency.” But what did that mean, exactly, outside of the non-FDA-regulated claims of vitamin D retailers? A new study says that vitamin D deficiency for people over 65 is 20 nanograms/milliliter of 25(OH)D in your blood. Fall below that for too long, and bad things tend to happen.

University of Washington researchers went looking for a bright statistical line to see how levels of vitamin D circulating in the blood correlated with the risk of a major medical event. “Major” in this case meaning: heart attack, hip fracture, cancer diagnosis, or death. (We can all agree that death is as major an event as it gets.)

Their sample was drawn from a study of 1,621 Caucasian adults that was intended to ferret out risk factors for (and progressive stages of) heart disease in people age 65 and over. They had an eleven-year timeline of 25-hydroxy-vitamin D levels–in short, 25(OH)D–to look at. (One glaring limitation here is that the original study included no one of color, and while the jury is still out, there’s some concern that melanin-protected skin can cut down on vitamin D production, just as SPF 8 does.)

Today, their findings appeared in the Annals of Internal Medicine: “Serum 25-Hydroxyvitamin D Concentration and Risk for Major Clinical Disease Events in a Community-Based Population of Older Adults.”

Luckily UW News is there to put results into English for you: “[T]he researchers concluded that the risk of these disease events rose when the concentration of 25(OH)D fell below 20 ng/milliliter or 50 nmol/liter.”

The first thing to note is that as Dr. Ian de Boer, assistant professor of medicine in the Division of Nephrology, points out, this is mostly in line with the threshold level suggested by the Institute of Medicine. Here’s the NIH on IOM recommendations: “Practically all people are sufficient at levels ≥50 nmol/L (≥20 ng/mL); the committee stated that 50 nmol/L is the serum 25(OH)D level that covers the needs of 97.5% of the population.”

Daily supplements of 600 t0 800 IU of vitamin D3 should do the trick, if you’re not getting much vitamin D from anywhere else. (The Institute of Medicine, by the way, does not recommend exceeding 4,000 IU per day of vitamin D3 for adults.) A separate study on vitamin D dose response in post-menopausal women found that “response was curvilinear and tended to plateau at approximately 112 nmol/L in patients receiving more than 3200 IU/d of vitamin D3. The RDA of vitamin D3 to achieve a 25 (OH)Dlevel greater than 50 nmol/L was 800 IU/d.”

The second thing suggested by the study is that vitamin D levels are best understood in terms seasonal snapshots: Typically, you will top off the tank in summer, thanks to exposure to the sun. If it’s not replenished, that vitamin D bank balance gets drawn down all through next spring, so that you may be lower on vitamin D in March than October, even though the amount of sun is about the same. You might think you’d increase supplements most in winter and taper off in spring, but this study indicates otherwise.

News, Politics, Transportation

The War on Running People Down in the Street

3 Comments
If you lived here, you could have a car in your living room by now. This 24th Ave E & Montlake Blvd apartment's guard rail is put to heavy use each year. (Photo: MvB)

UPDATE: Thanks to Andrew Sullivan and Sightline for the links.

It’s a sad fact that you have to get out of your car, occasionally, and at those times you’re vulnerable if you’re anywhere near a street. Short of only patronizing drive-thrus, and making sure your home comes with a garage, there’s one sure way of bettering your odds of living peacefully with cars.

That’s slowing down the car before it hits you.

In “The War On Kids, the Elderly, and Other People Who Walk,” Sightline’s Eric de Place is writing about a bill before Washington legislature, which would allow cities to set 20-mph speed limits on their residential streets, without paying for an engineering and traffic study first. It seems picayune. What difference could five miles per hour make? It turns out to be life-and-death, because the relationship of fatalities to speed is not linear.

Someone hit by a car traveling at 40 miles per hour has an over-80-percent chance of being killed. At 30, it’s still 37 to 45 percent. But at 20, it’s just five percent. The key factors are stopping time and response time–at 20 miles per hour, the driver is in control of their car, and can stop before hitting someone. As you increase speed, you have less time to respond, while stopping distance increases.

There are apparently people for whom a five mile-per-hour difference is a bridge too far. Their time is far too valuable (despite their predilection for traveling long distances on residential streets) and in their cost-benefit ratio, the cost of a few lives is worth it. I don’t know how else to put it.

When you peruse the Seattle Department of Transportation’s 2010 Traffic Report, you learn that 529 pedestrians were hit by people in cars last year. Over 8,000 times, drivers hit other cars–but in fact, the citywide collision rate has been trending downward. It’s pedestrians who are getting hit more often than before.

Image from SDOT's 2010 Traffic Report

The top three reasons for collisions seem indicative of a larger “my hurry is more important than your hurry” mindset: they were “not granting the right of way to a vehicle, inattention and following too closely.” Speeding, especially on arterials, can be a huge problem. SDOT found that a full 25 percent of SW Admiral Way traffic fell into the aggressive speeder category, exceeding the posted limit (30 mph) by ten miles per hour or more.

At Crosscut, senior citizen Doug McDonald notes that “Sixty percent of the dead pedestrians were senior citizens,” while in a majority of the pedestrian-hit-by-car incidents where responsibility could be assigned, the driver was at fault. (This is not to ignore the number of collisions caused by pedestrians strolling obliviously into the street, but the person they’re doing in is themselves.) In 2010, you were most likely to be killed by a car walking between 9 and 10 a.m., 1 and 3 p.m., and 6 to 7 p.m.

Interestingly, though you’d never know it from the complaints about from people driving cars about how terrible traffic is, Seattle’s average daily traffic the past two years is the lowest it’s been since 2000. And not by a negligible amount, either. 2003’s high of almost 980,000 daily vehicle trips fell to 900,000 in 2009, bouncing back slightly to 910,000 last year.

It’s not clear how much a 20-mph speed limit on certain residential streets would affect accident rates. There is always the question of whether people would obey the limit in the first place. But it doesn’t seem like a terrible thing, does it, if people want to request a lower speed limit where they live?