Marathon Running May Cause Short-Term Kidney Injury

by Dr Alex Jimenez | Diets, Fitness

Any marathoner will tell you that the grueling 26-mile races can do a number on the hips, knees, ankles and feet.

Now, a small study suggests that these tests of endurance are also tough on the kidneys.

“Marathon runners demonstrate transient or reverse short-term kidney injury,” said Dr. Chirag Parikh, professor of medicine at Yale University.

In his study of 22 participants in the 2015 Hartford, Conn. Marathon, Parikh found that 82 percent showed acute kidney injury after the race. In this condition, the kidneys fail to filter waste from the blood.

The good news is that the kidney injury seems to clear up within two days of the race, he said.

“On day 2, they are all fine,” Parikh said.

Runners likely don’t even know they’ve had this transient injury, Parikh said. “For the short term, I don’t think they would notice anything,” he said.

Parikh isn’t certain why the strenuous event is linked with kidney injury. But some potential causes include the sustained rise in core body temperature, dehydration, or the decreased blood flow to the kidneys that occurs during a marathon, he explained.

When the blood is pumped to the skin and muscles while running, he said, the kidneys may not get as much blood as they normally do.

Nor can Parikh say whether the effect might be cumulative, getting worse with more marathons run. It may be that the kidney adapts over time instead, he noted.

To evaluate this type of kidney injury, his team looked at blood and urine samples collected before and after the marathon. These tests included measuring blood creatinine levels and proteins in the urine, along with looking at kidney cells on a microscope. Creatinine is a waste product excreted by the kidneys; measuring it in the blood helps assess kidney health.

In a previous study, published in 2011, Dr. Peter McCullough, vice chief of medicine at Baylor University Medical Center in Dallas, and colleagues evaluated 25 men and women marathoners. They found 40 percent of the runners met the definition of acute kidney injury based on their blood creatinine levels.

In the new study, Parikh’s team also “performed an in depth evaluation of the urine and found evidence of injury,” McCullough said.

“The larger question looming is: do these repeated bouts of injury in endurance athletes lead to chronic kidney disease years later? Can anything be done about the injury at the time including hydration strategy?” McCullough said. More study is crucial, he added.

Parikh said additional research is also needed to assess whether certain people may not recover as quickly. For now, those with a family history of kidney disease should let their physician know they run marathons, he suggested.

Dr. Cathy Fieseler said marathoners who want to reduce their risk of kidney injury should avoid anti-inflammatory drugs before the race. Those drugs include over-the-counter ibuprofen (Advil, Motrin IB) and naproxen (Aleve), Fieseler said. Acetaminophen (Tylenol) is cleared through the liver.

Fieseler is a primary care sports medicine doctor at Christus Trinity Mother Frances Health System in Tyler, Texas. She’s also medical director of the American Running Association.

The study was published March 28 in the American Journal of Kidney Diseases.

Study: 10,000 Steps Per Day Not Enough

by Dr Alex Jimenez | Diets, Fitness

Wearable fitness monitors (think Fitbit) provide a “motivation alert” as you approach the magic number of 10,000 steps per day, with a “celebration” of lights on their displays when that goal is reached. But a new study shows that objective may not be anything to celebrate — and focuses on a new threshold for maximum health benefits.

The study, published in the March International Journal of Obesity, and reported in The New York Times, is based on mail carriers in Scotland, and researchers at the University of Warwick in England found that the 10,000-step regimen is too conservative. For optimum heart-health benefits, it’s best to go the extra mile — to 15,000 steps.

Mail carriers in Glasgow mostly cover their routes on foot, so researchers knew they would perfect test subjects for the study. They also knew office workers there were seated for most of the day, providing contrast participants. For their study, they followed 111 postal workers of both categories (56 mail carriers, and 55 office workers) and included both sexes between the ages of 40 and 60. Researchers compiled data on blood sugar levels, body-mass index (BMI — a measure of body fat based on height-to-weight ratio), waist sizes, and cholesterol levels. Participants each wore a fitness monitor throughout the day for a week, including time at work, at home and on the weekends.

Researchers compiled data based on activity during waking hours. This included time spent seated and on foot. What they found was enlightening. Between work and home, some of the office workers sat for more than 15 hours in total each day. The office workers who sat for most of the day tended to have larger waistlines, higher BMI numbers, and unfavorable cholesterol profiles. The researchers also figured in late-night shift work (which has been proven affect heart health), family history, and age.

The study also showed that for every hour spent sitting beyond five hours, office workers added about two-tenths of a percent to the likelihood of developing heart disease.

In contrast, any amount of walking or standing reduced the chances of having a large waistline and other risk factors associated with a healthy heart.

But the benefits of the postal carriers who walked the equivalent of at least three hours per day (the magic 15,000) were a step up: They had normal BMIs and waistlines and metabolic profiles — in other words, lessened risk of heart disease.

The study seems to confirm that the 10,000-step goal has not kept pace with modern waistlines and eating habits. Quite a few sources, including RunnersWorld.com, say the 10,000 steps-per-day goal gets its origins from Japan in the 1960s. Dr. Yoshiro Yatano, then a professor at Kyushu University of Health and Welfare, pegged the goal at 10,000 after concern over growing obesity rates. That’s roughly the amount of steps that would burn about 20 percent of a person’s daily calories at the time. He coupled his concerns with a pedometer that was developed in 1965 and the campaign took off.

But it’s a moving target in terms of optimum health benefits. Diets change. Even before the Glascow study, not all health experts agreed to the amount of steps necessary, and some argue the type of exercise makes a difference as well. In fact, the Centers for Disease Control and Prevention offers no step guides at all, preferring instead to focus on 150 minutes of moderate activity per week (which, in steps-per-day language, translates to about 8,000).

Of course, any amount of exercise is better than none at all, and it’s important to remember not to be discouraged if you can’t reach 15,000 steps per day or even 10,000 steps per day. But if you’re among those who set out to get the most heart-health protection possible, and you’ve relied on that magic 10,000, you might want to consider the results of the Glasgow postal workers. Better get moving.

'Low' Fat and Sugar Labels May Confuse Consumers

by Dr Alex Jimenez | Diets, Fitness

Food labels that say ‘low salt’ or ‘no fat’ may be misleading, suggests a new study.

These ‘low-content’ claims are based on comparisons with other foods and are not standard definitions. Making such a claim doesn’t necessarily mean the food is more nutritious than other brands, the authors say.

Consumers should “turn the package around and look at the entire nutritional profile as well as the ingredients list in order to get a better sense of whether the product overall is healthier or less healthy,” Lindsey Smith Taillie of the University of North Carolina at Chapel Hill told Reuters Health in a phone call.

Smith Taillie and colleagues analyzed data on more than 80 million food and beverage purchases made in the United States by 40,000 families from 2008 to 2012.

“We found that higher-income households tended to be more likely to buy products with these types of claims, which is consistent with previous research that suggests that claims tend to be more utilized by people with higher levels of education,” Smith Taillie said.

As reported in the Journal of the Academy of Nutrition and Dietetics, 13 percent of food and 35 percent of beverage purchases included products with some type of low-content claim. Low-fat purchases were the most common, followed by low-calorie, low-sugar, and low-sodium claims.

On average, packaged foods with low-nutrient claims had 32 percent fewer calories, 11 percent less sugar, and about half the fat and sodium compared to foods that didn’t carry any claims on the packaging.

However, some products with low-nutrient claims actually had more of that substance than foods without those claims.

Also, Smith Taillie said, when a product has a low-sugar claim, for example, it might have less sugar than a reference product or a similar product, “but it doesn’t mean that it has an overall better nutritional quality.”

Or, “it could be a high-sugar food but be low in fat, so it’s going to say low fat on the label. That doesn’t mean that it’s healthy,” she said.

“Essentially, it can be kind of misleading to make a decision about a product based on a front-of-package claim,” she added.

The U.S. Food and Drug Administration regulates what products can claim, Smith Taillie said.

“It’s not that the products are technically wrong in making a low-content claim, it’s just that the rules that allow them to make this kind of claim vary by the claim and by food category,” she said.

Food labels can be confusing, agreed Melissa Rifkin, a dietitian with Montefiore Medical Center in New York City who was not involved in the study.

Understanding what a nutrition fact label means is more important than focusing on marketing claims,” Rifkin told Reuters Health by email.

Key items to focus on are serving size, quantity per container, calories, fat, sodium and sugar, she said.

A new and revamped nutrition fact label is under development, Rifkin said.

“Slowly we will begin to see all labeling take on the new information,” she said.