Summer salves expire
Welcome to our first reader column of summer.
Let’s start with a question regarding two essential tools of outdoor summer living — sunscreen and insect repellent. A number of you have written to ask how long these products remain effective. It’s true that most don’t include an expiration date on the packaging. However, the Food and Drug Administration requires sunscreen to maintain its original efficacy for at least three years. (Of course, that means you’ll have to remember when you made your purchase.) Most manufacturers say their insect repellents remain effective for two to three years. If you need a more precise answer, you can call or email the manufacturer’s customer service department and provide them with the lot number of the product you’re asking about.
A reader in Virginia thought we left out an important detail in our discussion of preventing deep vein thrombosis, which is the formation of blood clots, on long plane flights. “Never once did you mention wearing compression socks on the flight,” he wrote. “Doesn’t that help prevent DVT?” You’re correct that wearing compression socks or stockings can help reduce the risk of developing deep vein thrombosis. According to the National Institutes of Health, about 2 out of every 10,000 passengers develops DVT on a long flight. For those at high risk, knee-high compression stockings with compression strength between 15 and 30 mmHg are a good idea.
We received a lot of mail in response to a column about the importance of vitamin B12, an essential vitamin the body needs but doesn’t produce. The answers to your varied questions are: B12 is manufactured by bacteria living in the guts of a variety of mammals, fish and poultry. It’s available in animal products, including fish, meat, poultry, eggs, milk and milk products. It’s also available as a supplement, both over-the-counter and through prescription. OTC products, although not regulated by the FDA, are considered to be a reliable source of the vitamin. Studies have found no advantage of sublingual (under the tongue) B12 over tablet form. Most B12 supplements exceed the recommended dietary allowances (RDA) for adults of about 2 to 3 micrograms per day. However, the body absorbs only as much as it needs, and any excess of the water-soluble vitamin is excreted in the urine.