Ask the Experts: Natto’s Effect on Blood Clots; Measuring Potassium; Wool Allergy & Vitamin D
Q: I’ve hear that Natto is good for preventing blood clots. Could you please comment on the benefits, if any, of these Japanese fermented beans?
A: Judith C. Thalheimer, RD, LDN, managing editor of Tufts Health & Nutrition Letter answers: “There is not enough information to know conclusively if eating natto, a popular Japanese dish of soybeans fermented with Bacillus subtilis, can help prevent blood clots. Natto contains an enzyme (called nattokinase) that is very good at dissolving blood clots in laboratory studies. One study found this enzyme to be effective at dissolving blood clots in rats. There is some limited data that nattokinase supplementation in humans enhances markers of anticoagulation, but this is not definitive, and the amounts administered were higher than one would get by simply eating natto.
“Natto has an unusual smell, texture, and taste some people find objectionable. If you enjoy this traditional soy food, it can be a healthy addition to your dietary pattern, but it should not replace medications to prevent blood clots. To be on the safe side, if you are on anticoagulants you should inform your doctor if you eat natto regularly.”
Q: Nutritional websites and Nutrition Facts labels all seem to list different amounts of potassium in one cup of frozen spinach. How can this be?
A: Kyla Shea, PhD, a scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging Vitamin K Laboratory, answers: “The nutrient content of plant foods varies depending on where it was grown, soil conditions, weather, and other factors. For example, higher amounts of iron in the soil in which spinach is grown has been associated with lower amounts of potassium in the leaves. Food processing also impacts nutrient content.
“According to the USDA Food Composition Database (available online at FoodData Central or ndb.nal.usda.gov) there are 574 milligrams (mg) of potassium in one cup of ‘frozen spinach, chopped or leaf, boiled, drained’ with or without salt, and 840 mg in a cup of ‘spinach, cooked, boiled, drained.’ This represents the average amount of potassium in frozen or cooked spinach, respectively. However, the exact amount in the spinach you buy may be lower or higher, depending on where it was grown and how it was processed.
“Potassium is found in a wide variety of foods. Besides spinach and other leafy greens, try including foods like avocados, sweet potatoes, watermelon, beans, butternut squash, dried apricots, and bananas. Consuming a healthy dietary pattern that includes plenty of plant foods will insure you get enough potassium for good health, despite the confusing—but natural—variations in potassium content.”
Q: I have heard that a person who is allergic to wool should take vitamin D2 instead of D3. Is this true?
A: Bess Dawson-Hughes, MD, lab director of the Bone Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging, answers: “While some people allergic to wool have reported an allergic reaction to vitamin D3 supplements (particularly at high doses), there is very little scientific data to support or refute this claim. According to ConsumerLab.com, vitamin D3 (cholecalciferol) supplements are derived from either fish oil or lanolin (a natural waxy substance that helps sheep shed water from their wooly coats). If your doctor has recommended vitamin D supplements and you are concerned about taking a lanolin-derived product, look for fish-oil derived D3. Another option is to take vitamin D2, which may not be quite as effective as D3 at raising blood levels but is a good choice none-the-less. Vitamin D is a fat-soluble vitamin, so be sure to take it with a meal or snack that includes some healthy fat.
“Our bodies produce Vitamin D when rays from the sun strike the skin. Sun screen and clothing interfere with this process but are important for preventing skin cancer. Americans get most of their dietary vitamin D from fortified foods, particularly milk, ready-to-eat breakfast cereals, orange juice, and yogurt, and from natural sources like fatty fish (tuna, mackerel, salmon). Beef liver, cheese, and egg yolk also naturally contain some vitamin D (mostly D3), and some mushrooms provide D2.”
—Irwin H. Rosenberg, MD, is a senior scientist at the HNRCA Neuroscience and Aging Laboratory, a Tufts University professor, and Emeritus Dean.
The post Ask the Experts: Natto’s Effect on Blood Clots; Measuring Potassium; Wool Allergy & Vitamin D appeared first on University Health News.
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