DEAR DR. BLONZ: I know that activated charcoal is the main ingredient in the water filter cartridge I use, but I have seen this same substance sold as a dietary supplement that can act as a blood purifier. Is this possible? -- C.C. Berkeley, California
DEAR C.C.: Activated charcoal is a specially treated and purified form of charcoal. It is a very fine powder, giving it a large surface area. Fine, powdered charcoal is an adsorbent (note the “d”), which means it has an ability to attract and hold on to substances on its surface. Contrast that with an absorbent substance (note the “b”), where liquids are soaked up as if by a sponge. This adsorbency makes activated charcoal useful for water filters, because it attracts and holds heavy metals and unwanted minerals and odors.
Regarding the second part of your question, activated charcoal is often given after an accidental ingestion of poison. Its adsorbent qualities help grab the poison, limiting its negative effects on the digestive tract and preventing the poison from reaching the bloodstream. (According to a statement from the American Academy of Clinical Toxicology, activated charcoal is most likely to produce these benefits if administered within one hour of poison ingestion.)
Given that the activated charcoal itself is not absorbed into the body, it is unclear how it could work as a “blood purifier.” It could prevent a toxin from being absorbed, if used appropriately, but there is no evidence that it could act to purify toxins already in the blood. Also, it’s not wise to consume activated charcoal on a regular basis, especially around mealtime, as it can grab and prevent the absorption of essential nutrients.
DEAR DR BLONZ: I learned in school that the riboflavin in milk is destroyed by light. If that is true, why is milk allowed to be sold in clear containers? Am I wasting my money by paying more for it in opaque containers? -- S.T., Richmond, Virginia
DEAR S.T.: A “waste of money” assessment is a bit of a judgment call, but here are some of the things to consider. Milk is a perishable food, and exposure to light (whether natural or bright fluorescents) can destroy a percentage of certain nutrients. These include riboflavin (vitamin B2), vitamins C and B6. Light can also encourage the development of “off” flavors. Assuming proper storage temperatures are maintained, the duration and intensity of light exposure determines how many of these nutrients will be destroyed. Always check the date on the carton to be sure it’s within the designated period.
All things being equal, opaque containers, such as paper cartons, are best for preventing the type of nutrient destruction you mention. Glass provides the important element of recyclability, although many areas of the country also recycle plastic and cardboard cartons. Then there is the point that glass is heavier and more fragile, which will increase transportation costs. But whether plastic, glass or paper, the jug, bottle or carton will still contain a healthful food.
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.