Saturday, August 6, 2011

Why Does America Have a Sodium Problem?

One of my wife's pet peeves is when students in her cooking classes are so concerned about the amount of salt that she uses for seasoning meat and fish.  We like fully-seasoned food.  And, occasionally, we are reminded of the "dangers" of sodium by such students or others who "are only trying to help."  But, I suspect that we actually consume less sodium than most.  One thing that probably shocks people is the fact that we use a salt, Diamond Crystal Kosher (DCK), which looks larger than "normal" table salt.  Two teaspoons of DCK has about the same amount (weight) of salt/sodium as table salt---DCK appears twice as large as an equivalent amount of table salt.  I bet another reason for the surprise is that we season food from scratch.  We rarely use prepared foods.  And high-calorie foods like meat and fish requires a good bit of salt to make it taste good.  Of course, if you buy prepared foods, this salt has already been added, so you never see the shocking act of adding the proper amount of salt.

But, what is a proper amount of sodium?  The USDA tries to determine appropriate sodium levels as a function of "serving size", but I think this is ridiculous.  Depending on the food, one might consume many servings of one type of food, but few of another.  It seems to me that the closest thing we have to a constant in food is calories.  People naturally balance the amount of calories they eat, probably due to fullness/hunger instincts.  Different people eat different rates of calories, but each individual keeps a fairly constant calorie intake.  They might over/under-eat over short periods (a day or two), but quickly return to their normal rate.  So, I think the best way to define appropriate sodium intake is via calories.  The USDA says the typical diet is 2000 calories/day and recommends no more than 2 grams of sodium/day.  In studying various nutritional labels, this rate of 1 milligram of sodium per calorie seems quite reasonable.  Even foods we might think are high sodium, like potato chips, are fine. 100 grams of potato chips might look like a lot of sodium---388 mg. But, that is for 559 calories, or a rate of .69 mg sodium per calorie. You'll get full eating potato chips before eating too much sodium.

When my wife and I eat steak, we'll typically cook over 1 pound of meat. Here is the nutritional information for rib eye steak, a cut we often eat when we eat steak (which is not that often). Note that 1 pound of this raw beef has 1243 calories, but only 254 mg of sodium. So, based on the 1 mg/calorie rule, it requires another 1000 mg of sodium. That's a lot of salt, especially considering that salt is only approximately 39% sodium---6 grams of salt (one teaspoon) has 2.3 grams of sodium. Note that salt is NaCl (sodium chloride); the atomic weight of Na is appx. 39% of the weight of Na and Cl. So, that pound of rib eye steak needs approximately 1 teaspoon of DCK salt. This looks like a lot to someone who mostly eats prepared foods. But, in fact, even the USDA wouldn't complain.

If you turn the lens on deli meats, you might be surprised for a good reason. We're visiting family and this morning, we had Oscar Mayer Deli Fresh Honey Smoked Turkey Breast. I was curious of the sodium content, so I took a look at the nutritional label. 470 mg of sodium per 50 calories, or 9.4 mg sodium per calorie. Egad! If you eat 2000 calories of this deli meat, you'll consume 18.8 grams of sodium. Apparently, this is normal for conventional deli meat. Of course, "all natural" deli meat might be different. Recall that 2 pounds of steak has almost 2500 calories, yet only requires 2500 milligrams of sodium to taste good. Of course, Oscar Mayer proudly advertises the fact that it is 98% fat free and low calorie (per serving). But, servings are silly and our obsession with "fat free" is ridiculous. Our bodies need a reasonable amount of fat and humans seem to get fat much more easily on a high-carb, low-fat diet than one which includes a reasonable amount of fat.

My deli meat sodium discovery makes me realize just how important it is to avoid prepared foods. I've known that recommendation to be important, but I didn't realize that prepared foods can have 9-10 times the reasonable level of salt (1 mg/calorie). When we prepare our own food, we are careful to add just enough salt to enhance flavor. We would never come close to adding the amount of salt that is found in conventional deli meat! Yet, when we eat prepared foods, whether in grocery stores or in restaurants, we don't see the amount of salt that goes into the food and hence aren't as careful. So, I think the advice we are given to be careful of our sodium intake is a bit silly---we see most of the salt that goes into your food and hence are naturally careful. I believe those that need to be careful are people who rely on prepared and restaurant food for the majority of their calorie intake.

Tuesday, July 19, 2011

Pee After Sex

It sounds funny, and a bit annoying, I know. But, hear me out.

For years, my wife experienced painful urinary tract infections. As (what seemed like) luck would have it, these would develop overnight and I'd end up driving her to the emergency room at 2am because it was too painful to stand.

She talked to various ob/gyn doctors about the problem, often receiving the standard, useless (to her) advice of wearing cotton underwear, keeping the area very clean, wiping from front-to-back after using the bathroom, avoiding tight-fitting pants, and drinking cranberry juice. She was given an antibiotic at each emergency room visit to temporarily fix the problem, but she hated having to rely on antibiotics. She couldn't believe it when one ob/gyn recommended a constant, low-dose antibiotic preventative treatment.

After much searching, one doctor suggested that she pee after sex. He said that pee is highly acidic and will likely kill any bacteria that is growing around the urinary tract. It sounded painful/difficult. The last thing you want to do after sex is get up, drink lots of water and wait on the potty until something comes out! But, UTIs were more painful, so she gave it a try. A few months passed and she diligently followed the doctor's suggestion. No UTIs.

A few months later, I came down with some sort of painful infection in my scrotum. Unlike my wife, I hadn't been peeing after sex. I saw my doctor, but he didn't any particularly useful advice, and the infection resolved on it's own after a few days. But, this infection convinced me that I ought to be joining my wife in the after sex ritual.

Now, it's been over three years since we've been committed to peeing after sex and neither of us have UTI or similar infections. I see that peeing after sex is a standard recommendation for UTIs. But, it's somewhat buried. It'd be nice if they had some sense of the practical effectiveness, possibly organized by which strategies are more likely to work for different races, socioeconomic backgrounds, etc. 'course, that might alarm the political correctness police...

Friday, July 8, 2011

Yes, You Can Microwave (Some) Styrofoam

My wife's family is joining us for a vacation in New Hampshire near Storyland.  It seems like this is a standard summer vacation for all Boston-area families with small children like us.  It's easy to see why.  Our four-year-old daughter loved Storyland---Cinderella's castle, circus the flying whales, the twirling turtles and even the more scary rides like the Bamboo Chute.

This morning, my mother-in-law put a take-out styrofoam container into the microwave to warm up left-over pancakes.  My wife and I both cautioned this move, warning about the possibility of plastic chemicals leaching into the food.  She said it was fine---they do it all the time without any ill effects.  I was curious to find out the truth.  A Google search returned a consumer-oriented Harvard Medical School newsletter about exactly this issue.  The answer is "it depends".  Not all styrofoam will leach chemicals in sufficiently large enough quantities to arouse concern.  But, many of those containers are tested and labeled "microwave safe".  In particular, single-use containers such as take-out styrofoam boxes are generally not known to be safe and should not be used in the microwave.  Of course, the FDA is conservative with the "microwave safe" label, requiring 100-1000x less chemicals than have been shown to harm laboratory animals over a lifetime of use.  So, occasionally eating food out of microwaved take-out styrofoam boxes might be okay, but it's not clear and it's not a risk I'm willing to take.

Wednesday, June 22, 2011

(Don't) Wear Sunscreen

When I first heard this advice, I was about to graduate college with a Bachelor's degree. It was from an email "forward" which claimed that it was given by Kurt Vonnegut in a commencement speech. I recently discovered that, in fact, it was a Chicago Tribune newspaper column by Mary Schmich---the graduation speech she'd give if she were ever invited to give one. Wikipedia provides full details about "Wear Sunscreen".

I enjoyed this pho-graduate-speech and thought that it contained excellent advice. At the time, I didn't think seriously about the "wear sunscreen" advice---I'm fair skinned and it seemed essential for avoiding burns even though I sometimes ignored the advice of my parents to apply it liberally and regularly. But, more recently, I've wondered whether "wear sunscreen" is really such great advice. Sunscreen blocks UVB rays which are used by the body to produce Vitamin D. About a year ago, I learned that I am Vitamin D deficient and could use more, not less, UVB rays. Furthermore, sunscreen interacts with skin in ways that may increase the chances of skin cancer; and, sunscreen only partially blocks UVA rays which penetrate more deeply than UVB and have more potential to damage skin cells. These concerns are well-documented in the Wikipedia article on the potential health risks of sunscreen. One fact I did not know about is that increased sunscreen usage is positively correlated with skin cancer rates. Sunscreen is effective at preventing sunburn, but there is no evidence that sunscreen prevents skin cancer. If anything, evidence points in the opposite direction, that using sunscreen increases your chances of getting skin cancer. See, for example, Could Sunscreens Increase Melanoma Risk? and Beneficial Effects of Sun Exposure on Cancer Mortality.

As usual, it seems that the best approach here is moderation. Wearing sunscreen may be dangerous, but repeated severe sunburns are definitely dangerous (if not extremely uncomfortable). Some sun exposure when the sun angle is large enough to provide significant UVB (only in spring/summer around noon in Boston) is greatly beneficial. But, so much that it causes burns is undesirable. It seems that the best approach is to get a small amount of sun as many days as possible, but limit the amount of time you spend in direct sunlight each day. In cases where you know you are going to be in the sun for extended periods of time, the best approach may be to use a full-spectrum sunblock which minimizes the amount of UVA, UVB and infrared light which reaches your skin.