DEAR DR. BLONZ: I was at a large dinner party where they served sea salt with the meal. However, I have been avoiding modern sea salt if its source is evaporated seawater.
I have traveled extensively to islands in the Caribbean where seawater is channeled into successive ponds on land, where it is evaporated to salt crystals and harvested for market. These islands typically have limited sewage treatment facilities, and waste with toxic components is discharged directly into the sea. This makes me suspect of salt made this way. -- B.T., Scottsdale, Arizona
DEAR B.T.: The FDA has a strict "good manufacturing practice," or GMP, for sea salt, and products adhering to the guidelines earn GRAS status: generally regarded as safe. While there can be trace amounts of heavy metals such as lead and arsenic in evaporated sea salt, they tend to be below the level of concern.
In recent years, though, science has discovered a different potential issue with sea salts: the presence of microplastics. Check out this article in National Geographic, which found microplastics in 90% of the evaporated salts it checked from around the world (visit b.link/4xzzx).
This all makes the case for doing your homework before you buy. If considering a particular sea salt, read the product label about the purity of the water from which it was harvested. Get more answers by contacting the company, or checking online, to see if the brand has had purity issues in the past.
DEAR DR. BLONZ: You often mention epidemiology when describing research, but I am not sure what that is. Could you give me a brief explanation? -- S.F., Seattle
DEAR S.F.: Epidemiology is the science that investigates connections between specific events, such as the occurrence of a disease, and a particular behavior pattern. In matters of nutrition, this could be an association between diet, exercise and a pattern of health or disease. Epidemiological research can help suggest what's going on, but it cannot tell you what's causing what with any precision. Some findings can be informative and on target, while others may only be coincidental.
For example, one study had found that inner-city children suffering from iron-deficiency anemia were more likely to have lead poisoning. The study showed that these items were connected, but it couldn't say what was causing what. Inner-city residents often have a greater exposure to lead, which could be present in peeling lead-based paints. So, did the lead causing the anemia, or was it the other way around?
Additional studies filled in the blanks by providing a plausible mechanism behind the relationship. In this case, it was discovered that that low blood iron (anemia) facilitates lead absorption.
This is an example of epidemiology at work, but studies can also uncover strange relationships. One of my favorites, uncovered while in graduate school, came from a list of statistically "connected" phenomena. There was a finding that physicians who eat more meat and consume more alcohol have one-third the risk of dying in a plane crash. So, does that indicate that it's legitimate science to encourage doctors to grab a burger and a beer before they board their flight? Hardly.
In that case, as in all others, we need to understand a plausible mechanism before giving full credence to results from epidemiology. For more, check out the Centers for Disease Control and Prevention's lesson on epidemiology at b.link/cmx954.
Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to firstname.lastname@example.org. Due to the volume of mail, personal replies cannot be provided.