DEAR DR. BLONZ: I believe I heard, at some point in my schooling, that rinsing and draining canned vegetables reduces their sodium content as much as 25 to 30 percent. I have searched through everything I have (old textbooks, lecture notes, etc.) and cannot find a single reference. I can’t believe there isn’t something more recent than that! Do you know how much the sodium content is reduced when canned vegetables are rinsed? Are you aware of any research articles on this topic? -- L.K., Phoenix
DEAR L.K.: Salt, or sodium chloride, dissolves easily in water, so rinsing canned vegetables and beans will certainly reduce their sodium content. As for the exact formula or percent reduction for a particular food, it would depend on total sodium in the food, the amount of added salt and the volume of water exchanged.
There is no specific data that I am aware of that works for all products. But you should be assured that rinsing canned vegetables is an effective way to cut their sodium content -- perhaps as much as 40 percent in some cases. I hope this helps.
DEAR DR. BLONZ: I am a big fan of tomatoes, and understand they contain a healthy compound called lycopene. I know that cooked tomatoes contain more lycopene than raw, and it is recommended to consume cooked tomatoes (such as sauce with pasta or pizza). I also like sun-dried tomatoes. What is the comparable vitamin and mineral content of sun-dried versus fresh tomatoes? -- S.S., Sacramento, California
DEAR S.S.: Sun-drying reduces vitamin C and vitamin A, and, to a lesser degree, some of the other vitamins. But the mineral content will remain largely the same. As for the lycopene, it helps to understand that cooked tomatoes don’t contain any more lycopene than fresh. Rather, the lycopene is chemically bound inside the cell matrix of the fresh tomato plant, and the cooking process breaks the bond, thus making the lycopene more bioavailable (absorbed with greater efficiency). Given that lycopene is a fat-soluble substance, eating tomatoes with some fat can add to lycopene’s bioavailability.
Sun-drying isn’t the same as cooking, but from the standpoint of lycopene absorption, it’s probably better than having fresh. When the water is removed, the cells do shrink, and they can break, especially if heat is used during the drying process.
Go ahead and enjoy your sun-dried tomatoes, but be sure to give them a good chew. If the lycopene is what you’re after, eat them with -- or within an hour of -- a fat-containing meal or snack.
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