To Salt or Not to Salt? A Stubborn Question

The recent New York Times article ‘No Benefit Seen in Sharp Limits on Salt in Diet’ should not make you run to your favorite restaurant to catch a salty meal. Sodium is very necessary for health and is found in most of our foods, but just how much (or how little) should be a part of our diets is not so easy to nail down.

This article, and the research cited, brings into question the value of the lowest level of sodium currently recommended by the US Department of Health and Human Services and the US Department of Agriculture — daily sodium intake to less than 2,300 mg per day, and 1,500 mg per day for high-risk subpopulations including persons older than 51 years, Blacks, and persons with hypertension, diabetes, or chronic kidney disease (CKD). Currently, few Americans reach these sodium targets. In fact, on average we consume 3,400 mg of sodium per day.

So, who should be restricting their sodium, and what does watching the salt do for your health?

High Blood Pressure

Patients at risk for CKD with hypertension should not be phased. Low sodium diets can benefit them in a number of ways. High blood pressure currently affects approximately 72 million Americans.  Even among those who are treated with medications, over 30% have a blood pressure above the widely recognized target of less than 140/90 mm Hg.  Controlling blood pressure lowers the risk of stroke, coronary heart disease and kidney disease. Many studies have shown the benefit of reducing sodium intake to reduce blood pressure.

Dietary Sodium and CKD

Two small studies suggest that reducing sodium intake can decrease a marker of kidney damage — proteinuria — in patients with CKD, with or without diabetes.  Most patients with CKD are salt sensitive, or their blood pressure increases with more salt intake. The National Kidney Foundation’s Kidney Outcomes Quality Initiatives CKD US Commentary on the 2012 KDIGO Clinical Practice Guideline for Management of Blood Pressure in CKD recommends a dietary sodium target of less than 2,000 mg (in press). This 2,000 mg level is also recommended by the World Health Organization.

But how low is too low?

In general, there are patients who are dehydrated and need more fluid and sodium intake. Also, there are rare patients with CKD and what doctors call salt-wasting nephropathy. These people require more sodium intake than is generally recommended because of excess urinary losses of sodium.

Other studies have shown people with heart failure treated with diuretics or “fluid pills” and blood pressure medicines have an increased risk of hospitalization and even death if they have very low sodium intake. People with heart failure have to delicately balance their sodium — too much salt in the diet may result in fluid in the lungs or heart failure; too little may impair blood flow to the vital organs the brain, heart, and kidneys.

Implementation

The fact is, while there is still debate surrounding optimal sodium intake, most experts agree that we consume too much. Should we all aim for a diet with 1,500 mg of sodium or less? Probably not. Besides, sodium is so ubiquitous that if one is eating a truly low-sodium diet, it probably means they are not eating very much food at all.

No matter how you look at it, this article is big news, showing a positive relationship between higher sodium intake and cardiovascular disease (CVD) risk and all-cause mortality. However, the researchers also conclude that there is insufficient evidence to recommend lowering sodium intake below 2,300 mg a day because they are uncertain if it increases or decreases risk of CVD outcomes.

We should be concerned that the take-away message from anyone reading the NYT’s article is that reducing sodium can be bad for your health. In contrast, a careful read of the report makes that assumption less clear. More research is needed on this topic and as an organization we support further investigation in this arena.

Dr. Joseph Vassalotti is the National Kidney Foundation’s Chief Medical Officer

Traffic Can Be Bad For Your Health

By Dr. Stephen Pastan

You may have seen the study that came out this week stating that living near a major roadway can increase the risk of developing kidney problems. Researchers examining stroke patients found that those who lived closer to a major road had reduced kidney function, comparable to a person four years older. That means their kidneys lost four years of life, or about 4% function, simply due to where they live. This is the latest finding that shows adverse health effects from living close to major roadways, such as an increased risk of death after heart attack. The presumed cause of this cardiovascular and kidney stress may result from the ill effects of traffic-related air pollution, although noise pollution or other urban stressors could also be playing a role. 

It should be noted that the patients in these studies were at high risk for vascular disease, in this case stroke patients, who may be more susceptible to the damaging effects of pollutants than the general population. But it does make me question whether patients who already have chronic kidney disease may also be more sensitive to pollutants – we know that smoking cigarettes worsens chronic kidney disease.  This is a good area for future research. Statistical associations are not always found to hold up over the long term — initial data on the cancer risk from living near power lines have not panned out, and we are still debating whether cell phones cause brain cancer.  However, these findings are another reason to push for cleaner cars and cleaner air.  And now would be a good time to stop smoking.

Dr. Stephen Pastan is a member of the National Kidney Foundation’s Board of Directors. He is also Medical Director of the Kidney and Pancreas Transplant program at Emory University in Atlanta, Georgia

Donating a Kidney Hasn’t Slowed Me Down

By Donna Drasher

This past Saturday I ran the Healthy Kidney 10K in Central Park in honor of my dad. My dad has Type II diabetes, and over the last 15 years has suffered from numerous health issues, including having his right leg amputated below the knee due to a diabetic ulcer on his foot.

About three years ago, after suffering from complications to an appendectomy, we found out he was on the verge of kidney failure. We started to weigh our options, and after meeting with a few doctors, the subject of a kidney transplant came up. I never thought transplant would be an option given that my dad has suffered complications from many of the surgeries he’s undergone over the years, but the doctors assured us they would make sure it would be safe for him before proceeding.

Learning from Kidney Disease

By Yenny Love

Kidney failure has greatly affected my life. Even writing this piece was not easy. It still hurts just thinking about everything my family has experienced in the past few years when my younger brother was diagnosed with  kidney disease. Trust me, I understand how the process can drag you down and wear you out! I also understand why family support is so crucial.

My brother Anthony was diagnosed with kidney failure in December 2011, one week before Christmas. Sitting in the ICU at Saint Peters Hospital, I watched as my little brother slept, the sound of machines keeping him alive. My mother was lying on the extra bed next to him and I was trying to sleep in between two chairs that I pulled together. I wasn’t comfortable at all but it was not like I could sleep anyway.

Good News For Kids on Dialysis

By Beth Piraino, MD

Kids with kidney failure are better off than most people imagined, according to new research released this week. The study showed that survival rates in children on dialysis have improved over the last two decades, in the United States. Death from cardiovascular and infectious diseases has decreased in this population and the care of children with kidney diseases has improved over this period of time.

Why has this happened? Researchers aren’t 100% sure, but those of us in the field believe that registries established by pediatricians to collect and disseminate data on all children on dialysis has certainly contributed to improvements in the care of children. These registries have allowed physicians to share important information throughout North America, and in some instances, internationally. Better approaches to preventing infections in children on dialysis as well as better control of hypertension and other cardiovascular risk factors have no doubt also contributed to the decrease in mortality. Additionally, doctors are working to provide early kidney transplantation to these children to minimize time on dialysis –another measure that improves survival.

Dr. Beth Piraino is the President of the National Kidney Foundation.

Sharing Experiences is the Best Way to Fight Kidney Disease

By Larry Blustein, Managing Editor, South Florida Sun Times

When I decided to write my guest blog post each month, it was with the idea of bringing all of us who are dealing with kidney disease together.

I wanted those who are battling the disease as well as those close to the situation to share the little things that may indeed be a huge help to all of us. With a schedule that demands 80 hours of my week, I am often reminded what I am living with each day as my body, which I use to dictate how I feel, is suddenly telling me when enough is enough.

Another Good Reason to Get Moving

By Beth Piraino, MD

Are you stuck on the couch most of the time and not exactly motoring down the street when you do finally get up? New research released this week will push you to put some energy in that step. The study, published in the Journal of the American Society of Nephrology, found that “frailty” which was defined by a simple measure –walking slowly–is a strong predictor of early death.