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Kidney stones Credit: Wikipedia

Kidney stones are not only incredibly painful, but are also associated with chronic kidney disease, osteoporosis, and heart disease. New research suggests a good way to prevent a recurrence of kidney stones is to increase consumption of calcium and potassium rich foods. Very simple!

The Mayo Clinic researchers also found certain dietary factors associated with a higher risk of getting kidney stones for the first time. They are: lower consumption of calcium, potassium, caffeine (e.g., coffee, tea), and phytate in the diet. As well as a lower daily fluid intake. Foods matter!

Some foods to eat to lower the risk of kidney stones:

Calcium rich foods: dairy products (e.g., cheese, milk, yogurt), dark green leafy vegetables (e.g., spinach, collard greens, broccoli, kale), and sardines. [Note: Calcium supplements are associated with kidney stones, while eating calcium rich foods is protective.]

Potassium rich foods: include legumes (beans and lentils), potatoes (with skins), tomatoes, some fruits (e.g., bananas, kiwi, orange juice, melons), dairy foods, some seafood (e.g., salmon, halibut, tuna, shad, clams), leafy greens (e.g., spinach), yam, squash.

Phytate rich foods: include beans, legumes, unprocessed cereal grains (e.g., oats), nuts, seeds, and potatoes.  Some people have referred to phytate rich foods as "anti-nutrients" and say to avoid them (because they may slow down absorption of certain minerals). However, recent research finds that the health benefits of eating phytate rich foods (e.g., they are antioxidants, anti-inflammatory) and other plant foods outweighs any concerns.

From Science Daily: Diets higher in calcium and potassium may help prevent recurrent symptomatic kidney stones

Kidney stones can cause not only excruciating pain but also are associated with chronic kidney disease, osteoporosis and cardiovascular disease. If you've experienced a kidney stone once, you have a 30% chance of having another kidney stone within five years.  ...continue reading "Certain Foods Lower the Risk of Kidney Stones"

Another large recent study found that lowering sodium intakes (less than 2500 milligrams per day) wasn't linked to lower blood pressure. Over the course of 16 years, the researchers found that the study participants who consumed less than 2500 milligrams of sodium a day had higher blood pressure than participants who consumed higher amounts of sodium. However, the current 2015-2020 Dietary Guidelines for Americans recommends limiting sodium intake to 2,300 grams a day for healthy people. The researchers felt that based on recent studies with similar findings that the sodium guidelines should be changed.

This 16 year study found that people in the study who had normal intakes of sodium, but also higher intakes of potassium, calcium and magnesium exhibited lower blood pressure over the course of the study. And those people with higher combined intakes of sodium (3717 milligrams per day on average) and potassium (3211 milligrams per day on average on average) had the lowest blood pressure.

Some good potassium foods:  avocado, winter squash, sweet potato, potato, white beans, banana, spinach, salmon, dried apricots, tomato sauce, beans, and milk. Some good magnesium foods: dark leafy greens, nuts, seeds, fish, beans, whole grains, avocados, yogurt, bananas, dried fruit, dark chocolate. Some good calcium foods: milk, cheese, yogurt, kale, sardines, broccoli, white beans, and rhubarb. From Science Daily:

Low-sodium diet might not lower blood pressure: Findings from large, 16-year study contradict sodium limits in Dietary Guidelines for Americans

A new study that followed more than 2,600 men and women for 16 years found that consuming less sodium wasn't associated with lower blood pressure. The new findings call into question the sodium limits recommended by the current Dietary Guidelines for Americans. Lynn L. Moore, DSc, associate professor of medicine at Boston University School of Medicine, will present the new research at the American Society for Nutrition Scientific Sessions and annual meeting during the Experimental Biology 2017 meeting, to be held April 22-26 in Chicago.

"We saw no evidence that a diet lower in sodium had any long-term beneficial effects on blood pressure," said Moore. "Our findings add to growing evidence that current recommendations for sodium intake may be misguided." The 2015-2020 Dietary Guidelines for Americans recommends limiting sodium intake to 2,300 grams a day for healthy people. For the study, the researchers followed 2,632 men and women ages 30 to 64 years old who were part of the Framingham Offspring Study. The participants had normal blood pressure at the study's start. However, over the next 16 years, the researchers found that the study participants who consumed less than 2500 milligrams of sodium a day had higher blood pressure than participants who consumed higher amounts of sodium.

Other large studies published in the past few years have found what researchers call a J-shaped relationship between sodium and cardiovascular risk -- that means people with low-sodium diets (as recommended by the Dietary Guidelines for Americans) and people with a very high sodium intake (above the usual intake of the average American) had higher risks of heart disease. Those with the lowest risk had sodium intakes in the middle, which is the range consumed by most Americans.

The researchers also found that people in the study who had higher intakes of potassium, calcium and magnesium exhibited lower blood pressure over the long term. In Framingham, people with higher combined intakes of sodium (3717 milligrams per day on average) and potassium (3211 milligrams per day on average on average) had the lowest blood pressure.....Moore says that there is likely a subset of people sensitive to salt who would benefit from lowering sodium intake, but more research is needed to develop easier methods to screen for salt sensitivity and to determine appropriate guidelines for intakes of sodium and potassium in this salt-sensitive group of people.

Nothing new here, but good to have it discussed again: eating foods high in potassium and low in sodium (salt) lowers blood pressure. Why should we care? Hypertension (high blood pressure) is a global health issue. The World Health Organization estimates that hypertension is responsible for at least 51 percent of deaths due to stroke and 45 percent of deaths due to heart disease.

Eating the potassium rich foods seems to be key. Some foods high in potassium: bananas, baked potatoes, sweet potatoes, dark leafy greens (e.g., spinach, kale), tomatoes, mushrooms, beans (e.g., white beans, pinto beans), lentils, nuts, broccoli, apricots, milk. In other words, eat an assortment of fruits, vegetables, beans, and nuts to get potassium. And coincidentally these same foods are low in sodium (salt) - a win-win for heath. From Science Daily:

Fruits and vegetables' latest superpower? Lowering blood pressure

Eating potassium-rich foods like sweet potatoes, avocados, spinach, beans, bananas -- and even coffee -- could be key to lowering blood pressure, according to Alicia McDonough, PhD, professor of cell and neurobiology at the Keck School of Medicine of the University of Southern California (USC). "Decreasing sodium intake is a well-established way to lower blood pressure," McDonough says, "but evidence suggests that increasing dietary potassium may have an equally important effect on hypertension."

McDonough explored the link between blood pressure and dietary sodium, potassium and the sodium-potassium ratio in a review article....McDonough's review found several population studies demonstrating that higher dietary potassium (estimated from urinary excretion or dietary recall) was associated with lower blood pressure, regardless of sodium intake. Interventional studies with potassium supplementation also suggested that potassium provides a direct benefit.

McDonough reviewed recent studies in rodent models, from her own lab and others, to illustrate the mechanisms for potassium benefit. These studies indicated that the body does a balancing act that uses sodium to maintain close control of potassium levels in the blood, which is critical to normal heart, nerve and muscle function. "When dietary potassium is high, kidneys excrete more salt and water, which increases potassium excretion," McDonough says. "Eating a high potassium diet is like taking a diuretic." "If you eat a typical Western diet," McDonough says, "your sodium intake is high and your potassium intake is low. This significantly increases your chances of developing high blood pressure." 

But how much dietary potassium should we consume? A 2004 Institute of Medicine report recommends that adults consume at least 4.7 grams of potassium per day to lower blood pressure, blunt the effects of dietary sodium and reduce the risks of kidney stones and bone loss, McDonough says. Eating ¾ cup of black beans, for example, will help you achieve almost 50 percent of your daily potassium goal. [Original study.]

A banana a day keeps the doctor away? A recent large study found that older women who eat foods with higher amounts of potassium may be at lower risk of stroke and death, when compared to women who eat fewer potassium rich foods. The association was with ischemic stroke (caused by clot) and not hemorrhagic stroke.

Some good food sources of potassium are: bananas, cantaloupe, grapefruit, oranges, white and sweet potatoes, and white beans. The U.S. Department of Agriculture recommends that women eat at least 4700 mg of potassium daily, but in this study the average intake of the postmenopausal women was 2611 mg per day.

This study followed  90,137 postmenopausal women (aged 50 to 79 years at baseline), and followed them an average of 11 years. Now this same study needs to be done with men and women of all ages. From Science Daily:

Potassium-rich foods cut stroke, death risks among older women

Older women who eat foods with higher amounts of potassium may be at lower risk of stroke and death than women who consume less potassium-rich foods. The health benefits from potassium-rich foods are greater among older women who do not have high blood pressure. Most older American women do not eat the recommended amounts of potassium from foods.

"Our findings give women another reason to eat their fruits and vegetables. Fruits and vegetables are good sources of potassium, and potassium not only lowers postmenopausal women's risk of stroke, but also death."

Researchers studied 90,137 postmenopausal women, ages 50 to 79, for an average 11 years. They looked at how much potassium the women consumed, as well as if they had strokes, including ischemic and hemorrhagic strokes, or died during the study period. Women in the study were stroke-free at the start and their average dietary potassium intake was 2,611 mg/day. Results of this study are based on potassium from food, not supplements.

The researchers found: -Women who ate the most potassium were 12 percent less likely to suffer stroke in general and 16 percent less likely to suffer an ischemic stroke than women who ate the least. -Women who ate the most potassium were 10 percent less likely to die than those who ate the least. They also said there was no evidence of any association between potassium intake and hemorrhagic stroke, which could be related to the low number of hemorrhagic strokes in the study.

The U.S. Department of Agriculture recommends that women eat at least 4,700 mg of potassium daily. "Only 2.8 percent of women in our study met or exceeded this level. "Our findings suggest that women need to eat more potassium-rich foods. You won't find high potassium in junk food. Some foods high in potassium include white and sweet potatoes, bananas and white beans."