The new study was led by Dr. Yiqing Song, associate professor of epidemiology at Indiana University's School of Public Health. According to the researchers, past studies that focused on the role of magnesium in regulating blood pressure have been relatively small, and produced mixed and controversial results. To help sort the data out, Song's group pooled the data from 34 clinical trials on magnesium supplements, which together involved more than 2,000 people.
The daily dosage of magnesium supplements used ranged from 240 mg to 960 mg. Most trials had participants meet or exceed the U.S. Recommended Dietary Allowance for daily magnesium intake.
Sifting through the collected data, Song's team detected a small but significant link between magnesium intake and healthy reductions in blood pressure.
The study found that taking about 368 mg of magnesium daily for about three months resulted in overall reductions in systolic blood pressure (the top number in a reading) of 2 millimeters of mercury (mm/Hg) and diastolic blood pressure (the bottom number) of 1.78 mm/Hg.
Higher magnesium levels were associated with better blood flow -- another factor linked to lower blood pressure, the researchers added.
Song and his colleagues believe that the benefits of magnesium in regulating blood pressure may only apply to people with a magnesium deficiency or insufficiency.
Still, the finding "underscores the importance of consuming a healthy diet that provides the recommended amount of magnesium as a strategy for helping to control blood pressure," American Heart Association spokeswoman Penny Kris-Etherton said in an AHA news release.
"This amount of magnesium [368 mg/day] can be obtained from a healthy diet that is consistent with AHA dietary recommendations," said Kris-Etherton, professor of nutrition at the University of Pennsylvania.
That means that, with a healthy diet, it isn't necessary to take magnesium supplements, the AHA said.
"We need to stress the importance of a well-balanced meal, not only for all the cholesterol lowering and sugar-modulating benefits, but for ensuring an adequate amount of magnesium in the blood," said Steinbaum, who directs Women's Heart Health at Lenox Hill Hospital in New York City.
She believes that, based on the new findings, "checking magnesium levels as part of a screening for heart health may become an essential part of prevention and for treatment of blood pressure."
Q and A
Q: I've heard that lettuce varieties have different nutritional value and some aren't worth eating. Is that true?
A: Yes. And no. There are many types of lettuce, and it's hard to go wrong with any of them. All are loaded with water and they have some fiber, which reduces the risk of colorectal cancer. The popular iceberg lettuce makes a crunchy salad and includes some vitamin K, folate, and beta-carotene, which converts to vitamin A. Other types of lettuce provide even more vitamins and phytonutrients. A cup of Boston or Bibb lettuce provides more than six times as much beta-carotene as iceberg, and dark green or red leaf lettuce contains even more -- about the same amount that's in half a small carrot. These lettuces are also high in lutein, another carotenoid that links to eye health. One cup of romaine gives you over 80 percent of the recommended amount of vitamin A and more than half of vitamin K. Romaine also contains the B vitamin folate that helps maintain healthy DNA and may play a role in protecting against cancer. You may also have seen the mixture of field greens called mesclun. Some mixes include mainly mild-flavored greens such as baby oak leaf and romaine, while other blends contain more peppery flavored greens, such as arugula and mustard. In general, nutrients in these greens are similar to that of romaine or leaf lettuce: high in beta-carotene and folate. Whatever type of lettuce you choose as your salad base or in your sandwiches, all are less than 10 calories a cup and can help keep you feel full without many calories. By mixing up your lettuce choices, you'll keep your salads interesting and pack in a variety of vitamins and other cancer protective compounds. - American Institute for Cancer Research.
RECIPE
To boost your greens, try this recipe for Spinach, Pear & Pomegranate Salad from Williams Sonoma's Healthy in a Hurry cookbook.
Spinach, Pear & Pomegranate Salad
1/3 cup walnut pieces
3 tablespoons cider vinegar
2 tablespoons extra virgin olive oil
1 tablespoon honey
1 teaspoon Dijon mustard
1/4 teaspoon salt
1/8 teaspoon freshly ground pepper
8 ounces baby spinach
2 ripe pears, cored and sliced
1/2 cup pomegranate seeds
1/4 cup blue cheese, crumbled
Preheat oven to 350 degrees. Spread walnuts on a baking sheet and toast in oven until lightly browned and fragrant, about 10 minutes. Immediately pour onto a plate to cool. Set aside. In a large bowl, whisk together vinegar, olive oil, honey, mustard, salt and pepper to make a dressing. Add spinach, pears, pomegranate seeds and walnuts to bowl to toss gently to mix and coat well. Divide salad among 4 plates or bowls and top each with about 1 tablespoon blue cheese. Serves 4.
Per serving: 260 calories, 6 g protein, 26 g carbohydrate, 16 g fat, 5 mg cholesterol, 5 g fiber, 350 mg sodium.
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