Low Salt Diets for Hypertension: A Good Idea or Bad Advice?

Hypertension is one of the most common health problems in our country.  To some degree, its a normal part of aging.  There are lots of things that can cause hypertension, and for some, a low salt diet may be a good idea.  These include people with heart failure or kidney failure, as their bodies simply can’t pump blood effectively or eliminate excess water and sodium effectively.  But for the vast majority of people who have hypertension, their hearts and kidneys are working fine, yet we still recommend a low salt diet.  Is this a good idea?

Blood pressure isn’t just about sodium.

Sodium is one of the most important extracellular ions in the body (meaning that its highest concentration is outside of the cells).  It’s important for lots of things, like regulating the gates of your cell membranes, allowing muscle contractions, and keeping your heart beating.  But it isn’t the only extracellular ion.  Potassium is another very important substance that works together with sodium to regulate all of these functions.  Researchers have shown that a higher intake of potassium counteracts the effects of sodium, even when there is excessive salt intake.  Researchers also believe that modern man consumes far less potassium from fruits and vegetables than our ancestors did.  So, is hypertension the result of too much  sodium intake, or a deficiency of potassium?

Magnesium is also an important electrolyte that is worth mentioning in any discussion of heart health.  Magnesium appears to not only lower the risk of developing hypertension, its also protective against diabetes, insulin resistance and inflammation, all risk factors for the development of heart disease.

Your body needs sodium.

As I said, sodium is one of the most important extracellular ions in the body.  Your kidneys regulate your sodium excretion very carefully to ensure that you don’t become dehydrated.  When the kidneys sense that there isn’t enough sodium, they’ll start holding on to more of it, therefore holding on to more water in an attempt to keep your vessels filled.  They’ll also secrete various hormones like renin and stimulate the adrenals to release aldosterone to increase vascular tension, thus leading to an increase in blood pressure.  Researchers have also shown that decreased sodium intake leads to increased triglycerides and cholesterol, and increased levels of the stress hormones adrenaline and noradrenaline.  Clearly, too little salt intake is a stressor on your body.

Drink plenty of water.

Ultimately, dehydration will cause low blood pressure.  But initially, your kidneys will respond to dehydration by trying to increase blood pressure.  Low level chronic dehydration may lead to hypertension, so be sure to drink water throughout the day.  The amount you need is different for everyone, but a good way to judge is by making sure your urine stays clear, you aren’t thirsty, and if you work outside, make sure you’re still sweating!  Not sweating in extreme heat is a sign of serious bodily distress.  If you are working outside and sweating a lot, you may want to consider using an electrolyte replacement drink, ideally one that isn’t high in sugar.  Coconut water is very close to the same electrolyte concentration as your blood, so its a great way to rehydrate.  Cut it down with some water if you don’t like the taste of it, but make sure you’re replacing your electrolytes and not just fluids.

Practical Application

As with everything on this site, it’s best to attempt dietary and lifestyle changes with the full knowledge and assistance of your physician.  Everyone is different and there are different reasons why people have high blood pressure, so you need to make sure that the changes you make will be safe for you.  If you have kidney disease, for example, your body can’t eliminate potassium, and eating foods high in potassium could put you at risk for life threatening cardiac rhythms.  That being said, here’s some tips for how to proceed with lifestyle changes after you’ve talked with your physician.

If you have high blood pressure and want to avoid going on medication, or come off your medication (with the guidance of your physician), it’s best to keep a daily log of your blood pressure.  Get a machine you can use at home and take your blood pressure every day, ideally around the same time.  Make sure to record if you’ve had an especially stressful day, or you’ve been exercising, or anything you think might affect your blood pressure.  A general record of what you had to eat that day, with an estimated salt intake, would also be helpful.  It’s best to avoid processed foods if you can, as you can’t control the amount of salt added to these foods, and they usually have ingredients that contribute to inflammation anyway.  Try to make as much of your own food as you can, and use your taste buds as your guide to salt intake.  Be sure to include foods with potassium, magnesium, and calcium in your diet, as these will help balance out your sodium intake.  (For a list of these foods, check here.)  And remember, modern soils are depleted of a lot of necessary nutrients, so taking a multivitamin will help ensure you get the vitamins and minerals you need.

Don’t forget the importance of limiting stress, as this is one of the biggest influences on blood pressure.  Take time throughout the day to breathe deeply, relax, and remember that your mood affects your blood pressure.  I’ve seen it work time and again with my patients, even when strong antihypertensives failed to work.

If you’re on an antihypertensive and want to get off it, or you want to avoid going on it, I hope you’ll take the time to discuss this with your doctor and make some lifestyle changes.  You have more control over your own health than you realize.

References:

F. Batmanghelidi, M.D. Your Body’s Many Cries for Water.  Global Health Solutions, Inc. 1997.

S. Bo, E. Pisu. Role of Dietary Magnesium in Cardiovascular Disease Prevention, Insulin Sensitivity, and Diabetes. Curr Opin Lipidol, 2008 Feb; 19 (1): 50-6. Turin, Italy.

RC Morris, O. Schmidlin, L.A. Frassetto, A. Sebastian. Relationship and Interaction Between Sodium and Potassium. Journal of the American College of Nutrition, 2006 Jun; 25 (3 Suppl): 262S-270S.

N.A. Graudal, T. Hubeck-Graudal, and G. Jurgens. Effects of Low Sodium Diet vs. High Sodium Diet on Blood Pressure, Renin, Aldosterone, Catecholamines, Cholesterol, and Triglyceride (Cochrane Review). American Journal of Hypertension (2012); 25 1, 1-15.

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