Ask the Experts: Apple Cider Vinegar; Zinc Absorption; Spinach Kidney Stones
Q: Will apple cider vinegar really improve blood pressure?
A: Jennifer Mayer, a dietetic intern at Tufts’ Frances Stern Nutrition Center, replies: “Using apple cider vinegar for medical purposes dates as far back as Hippocrates’ time. Back then people used it for antibacterial or antifungal reasons, but nowadays some claim that drinking two tablespoons a day has beneficial effects on weight, blood sugar, cholesterol and blood pressure.” The data are currently insufficient to use apple cider vinegar to lower blood pressure, however.
“The thought that apple cider vinegar improves blood pressure is attributed to a few different theories. The first is due to its potassium content. Potassium helps lessen sodium’s negative effects on blood pressure. The recommended intake of potassium for an average adult is 4,700 milligrams a day. To put things in perspective, a small banana has about 350 milligrams of potassium, while two tablespoons of apple cider vinegar has about 20 milligrams—less than 1% of what an adult needs in a day.
“The second idea is the vinegar’s potential weight-lowering properties. Apple cider vinegar has been shown to delay gastric emptying and inhibit the enzymes that help digest starch, causing moderate weight loss. While any weight loss helps lower blood pressure, apple cider vinegar’s weight loss benefits remains poorly studied and only result in a few pounds lost over a few months’ time.
“If adding apple cider vinegar to your diet, never drink it straight, talk to your doctor first and keep taking your regular blood pressure medications.”
Q: I read in your newsletter that plant sources of zinc such as whole grains, beans, nuts and seeds contain phytate, which blocks some of the mineral’s absorption. Is there any way to increase the zinc availability from these foods?
A: Junaidah B. Barnett, PhD, a scientist in Tufts’ HNRCA Nutritional Immunology Laboratory who has studied zinc, answers: “Phytate binds minerals such as zinc to form complexes that are not completely broken down during digestion, decreasing their bioavailability. The enzymes in these foods help release the minerals when they get wet, however. Thus, soaking, juicing, blending, fermenting, leavening with yeast and sprouting break down the phytate compounds in grains, beans, peas and lentils, releasing zinc and other minerals, leading to their increased absorption. Compounds in onions, garlic and other allium vegetables have also been shown to increase the availability of zinc from grains and legumes by as much as 50%, so consider adding them to grain and bean dishes.”
Q: Should I avoid eating spinach because it has oxalate found in kidney stones? I already have some kidney stones.
A: A Leanne Stephens, a dietetic intern at Tufts’ Frances Stern Nutrition Center, responds: “Before making major dietary changes or exclusions, talk to your doctor to find out exactly what kind of kidney stone you had. In America, the most common (about 75%) are calcium oxalate stones, caused by increased calcium and oxalate in the urine. The increased oxalate levels may be impacted by dietary intake, but could be caused by a build-up of oxalate produced naturally in your body.
“Treatment of kidney stones is unique to each individual, so consult your physician and a registered dietitian for a specialized treatment plan. In general, there is a recommendation for increased fluid intake of at least two to three liters per day, equal to 8½ to 12½ cups of water. This will help dilute your urine and flush out any precipitates that may lead to kidney stones. If your health care team decides that a reduction in food oxalate sources will prevent future kidney stone development, they may ask you to avoid certain foods and adjust your intake of other foods or supplements. Foods high in oxalate include spinach, rhubarb, star fruit, beets, tea, chocolate, nuts, wheat and legumes.
“Studies have found that boiling may reduce oxalate levels in spinach and other oxalate-containing foods, so you may still be able to enjoy spinach in small amounts. Additionally, calcium can bind oxalate in the intestinal tract and prevent its absorption, so drinking a glass of milk with your meals may also lower the amount of oxalate your body absorbs. Individuals who consume the RDA for calcium (1,000-1,200 milligrams/day) have a lower risk for kidney stone formation, so you may be asked to increase your dairy consumption or take a calcium supplement. High salt and meat intake have also been associated with development of kidney stones.”
The post Ask the Experts: Apple Cider Vinegar; Zinc Absorption; Spinach Kidney Stones appeared first on University Health News.
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