Reducing Sodium Intake—Good for Society, But Not for Everyone!
While a certain amount of sodium is essential for life, consuming an excessive amount can lead to bad outcomes. It has been estimated that the body requires between 250 mg and 500 mg each day for basic physiological functions (eg, to transport nutrients, transmit nerve impulses, contract muscles). We maintain a careful balance under hormonal control. Under certain circumstances when our bodies sense that we need more sodium, most individuals will crave sweet and salty foods. Our hormones and taste buds (sweet, salty, bitter, sour, and savory) not only provide us with pleasure, but also are nature’s way of keeping us in metabolic balance when necessary. As we age, however, data have suggested that we preferentially lose our taste buds for sweet and salty flavors, and our hormonal system also undergoes changes that favor hyponatremia. Food preferences, habits, cultural norms, and food availability also influence what types of food we eat and how much sodium is consumed.
While a medical intern, I was “forced” to eat the various diets I had prescribed for my patients. This wonderful exercise gave me a first-hand appreciation of just how awful tasting a low-salt diet may be if one does not use creative ways to enhance flavor. I have become more attuned to salt substitutes so that I can better advise my patients how to make food more enticing, knowing full well that some use potassium chloride instead of sodium chloride, presenting an additional risk for those with renal insufficiency. I have had many an older person who was put on a low-salt diet complain that food no longer was worth eating, and so had a major change in his/her caloric intake. At times, I choose to increase the dietary sodium intake that I would otherwise prescribe to improve the chances of obtaining a more normal diet, recognizing that I would need to increase the dose of diuretic and carefully monitor outcome. As with all aspects of medicine, we must strike a careful balance and understand the risks and benefits of our treatments.
As we get older, and our system of water and sodium is no longer functioning as it did during our youth, and our antidiuretic hormone increases, we tend to become hyponatremic. Excessive sweating, loss of sodium from diuretics, and sodium-restricted diets also contribute to low serum sodium levels in the elderly, at times presenting with life-threatening situations. While restrictions on our sodium intake are wise and well deserving of more attention and regulation, elderly persons should receive careful and individual consideration of their sodium status, good advice from their physicians, and monitoring as appropriate.
As a society, however, we clearly have a problem. Just pick up a package of frozen food or canned soup, or look at the menu at McDonald’s, or, for that matter, most restaurants, and you will see how easy it is to exceed the 2.3 grams of sodium recommended by the National Academy of Sciences to use as the guideline for daily sodium intake. Remember that the “no added salt” diet we were taught in medical school to provide anywhere from 4-7 grams of salt (1.6-2.8 g sodium), in fact, varies greatly depending on one’s choice of foods. Even if no salt is added at the dining table, the sodium content may exceed what we were originally taught, as salt has increased in our food preparation practices. There is also the added confusion of “salt” and “sodium.” Four grams of salt (NaCl) is equivalent to 1.6 grams of sodium (Na).
The Institute of Medicine (IOM) is now recommending that our daily allowance of sodium be reduced further to 1.5 grams per day, and even less for those over the age of 50. I am sure that most would be glad if everyone kept to the 2.3 grams previously recommended as the daily allowance of sodium, though perhaps if we aim lower we will be more successful in achieving a healthier diet for all. We know that high levels of sodium in our diet contribute to high blood pressure with its increased risk of cardiovascular disease, stroke, and renal failure. The IOM believes that reducing sodium intake in our diet can save over 100,000 lives each year. This is in addition to the improved quality of life that may result from less pedal edema, signs of congestive heart failure, and lower overall fluid retention.
Whether 1.5, 2.3, or some other value of grams of sodium per day as a limit is the answer for a given person I cannot say; in some individuals with congestive heart failure, cirrhosis, and kidney failure, even 500 mg of sodium can have adverse outcomes. Clearly, we must start somewhere, and I believe the increased level of awareness that is now surfacing will go a long way toward helping to reduce sodium intake. In fact, New York City is beginning to target sodium content in foods offered in restaurants in a similar manner to what they did for trans-fats. I am sure that a wave of more health-conscious programs will soon span the nation. So, how much sodium is in your food? The following are just some examples for you to ponder:
• McDonald’s Happy Meal with cheeseburger: 1040 mg
• McDonald’s Double Quarter Pounder with Cheese, ketchup, mustard, and pickles: 1380 mg
• Olive Garden’s chicken parmigiana: 3380 mg
• Campbell’s cream of mushroom soup, condensed, 1 serving: 870 mg
• Progresso Healthy Classics chicken noodle soup, 1 cup: 460 mg
• 4-inch bagel, 1: 449 mg
• Baked beans with pork and tomato, 1 cup: 856 mg
• Beef stew, canned, 1 cup: 947 mg
• Dill pickle, 1: 2000 mg
• Bread crumbs, dry, seasoned, 1 cup: 2111 mg
• Carrots, canned, 1 cup: 353 mg
• Miso soup, 1 cup: 2563 mg
• Pancakes, 2: 1104 mg
• Tuna salad, 1 cup: 824 mg
• Pumpkin pie, 1 slice: 349 mg
• Cottage cheese, low-fat 1% milkfat, 1 cup: 918 mg
• Kellogg’s Raisin Bran® cereal, 1 cup: 362 mg
• Tomato sauce, 1 cup: 1284 mg
I could go on, but you get the message. Even many of the foods we have associated with health, such as low-fat cottage cheese, do indeed present a problem if we are to begin to seriously limit our sodium intake. Portion size as listed on a product’s label may bear no resemblance to what is actually being consumed, multiplying the sodium content several fold. The cost of purchasing “low-sodium” foods is another challenge for many persons living on limited resources, not to mention the taste factor, which for some individuals is not insignificant! We need to be both creative and health-conscious to achieve our goals.
We are off to a good start, I believe, by further limiting our goal for daily sodium intake; a low-salt diet, however, can be “overdone” as stated previously, with significant consequences, particularly for elderly persons. Unless the food industry and restaurants explore ways to prepare foods that are appealing and tasteful, in our “fast food” and multitasked environment, we will continue to face an upward battle to achieve our goal of reduced sodium intake while maintaining health. In addition, merely substituting potassium chloride for sodium chloride as is frequently done may present other problems for the elderly and for those with renal insufficiency. Just as lard is being substituted for trans-fats in many places that have had to make a change in the way they prepare their food due to regulated bans on trans-fats, we may see similar and potentially problematic substitutions for sodium in prepared foods and restaurants. As healthcare providers, we need to be proactive and aware of food trends and lay press, and anticipate problems before they manifest in our patients. The sodium issue is out of the bag once again, and it is time for us to discuss this issue intelligently and practically with our patients.
Dr. Gambert is Professor of Medicine and Associate Chair for Clinical Program Development, Co-Director, Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Director, Geriatric Medicine, University of Maryland Medical Center and R Adams Cowley Shock Trauma Center, and Professor of Medicine, Division of Gerontology and Geriatric Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
Send comments to Dr. Gambert at: medwards@hmpcommunications.com