Salt - Evil Additive or Essential Nutrient?
Salt has been a highly valuable commodity throughout the history of mankind — so revered that terms like “worth their salt” are used widely to describe a person’s integrity. Yet today, every newspaper, magazine, and blog seems to be telling us to avoid salt like the plague!
With all the conflicting information, it’s no wonder one of the most common questions I get asked by patients and athletes alike is... “should I reduce my salt intake?” The low-salt dogma is now so ingrained many people don’t even stop to question the advice.. Is salt really an evil additive that increases the risk of high blood pressure and cardiovascular disease, or is there more to the story?
The Evolutionary Perspective On Salt
If we look back throughout evolution for answers, expert researcher estimated the average sodium intake to be approximately 800 mg per day amongst Paleolithic hunter-gatherer population, far less than today’s daily consumption of 3,300 mg.(1) This is still supported today by scientitists in the field of Paleolithic nutrition, such as Dr. Loren Cordain.
However, salt expert Dr. James DiNicolantonio PhD believes the early research in this area is flawed, because it overlooks the fact that our hunter-gatherer ancestors consumed the entire animal (not just the muscle meat, as per the initial research suggestions), including the blood, skin and cartilage of animals where massive amounts of sodium are stored. Taking this into account, he believes our hunter-gatherer ancestors likely consumed about 3,000-4,000mg of sodium daily, about the same as we currently do today and double the general recommended intake of government guidelines.
The Benefits of Salt
Salt is an essential mineral, without it you would die. Salt is critical for so many functions in the body it's nearly impossible to list them all, a brief selection includes; salt is required to maintain ideal blood levels in the body, to effectively pump your heart, to digest your food, for cells to communicate with one another, to make your bones and keep them strong, to prevent dehydration, etc. Salt is also crucial for preventing muscle cramping, supporting healthy nerve function, blood sugar balance, immune function and the general health of all cells in your body. The risks of not consuming enough salt are significant and rarely discussed.
If you're simply trying to lose weight and improve your health, restricting salt is likely not the answer either. The latest research shows long-term salt restriction can actually increase your risk of heart attack or stroke, elevate triglyceride levels, and actually worsens your insulin sensitivity (increasing your risk of weight gain and all chronic diseases, including heart disease).(2,3)
The Standard Recommendations for Salt
The American Heart Association (AHA) states you should aim for less than 2,300 mg daily to prevent high blood pressure and reduce your risk of cardiovascular disease (and less than 1,500mg if you're African American or have high blood pressure). It seems logical that if you simply reduce your intake of salt, you could reduce your blood pressure and improve your overall health, but where did these recommendations come from?
In the 1980s, a major worldwide study on the connection between salt intake and blood pressure was conducted, and researchers found that cultures in which sodium intake was low had lower incidences of high blood pressure and cardiovascular disease. Animal studies confirmed that rats fed very high sodium diets rapidly developed high blood pressure and subsequently the “war on salt” began and hasn’t stopped to this day.
The Research On Salt & Cardiovascular Disease
Does the research actually support a low-salt approach, or is it more hype than substance? A review of the research shows that our salt consumption in the 18th and 19th centuries was far greater than today, and the levels of heart disease in the population were extremely low.
Fast-forward to the 1970s when the Dietary Guidelines for Americans were released and recommended for the first time that Americans restrict their salt intake in attempt to fight heart disease (despite the Surgeon General at the time stating there was "no evidence" to support this recommendation).(4)
Since then, our overall salt intake has been steadily on the decline over the past four decades yet heart disease levels have hit records highs. In short, salt seems unlikely to be the culprit.
First, consider that 80% of the population with normal blood pressure (less than 120/80mmHg) are not sensitive to effects of salt raising blood pressure at all, while 75% of those with mild-hypertension are also not salt-sensitive, and even those with diagnosed hypertension (above 140/89mmHg) over half are also not sensitive to salt.(5)
Next, consider the countries with the lowest rates of cardiovascular disease (CVD) - like Japan, France, and South Korea - all eat high-salt diets.(6) (In fact, Japan has the longest life expectancy of any population on earth.) Alternatively, countries with the lowest salt intakes in Eastern Europe - about 50% less than the Japanese - have a 10-fold greater risk of death.
In Korea, the women with the highest salt intake have a lower risk of hypertension compared to low-salt eaters. Of course, the fact that salt is consume in Korean from salted kimchee and fermented foods, and in Japan via seaweeds and fish have a huge impact on these effects.
What about if you already have hypertension? The research does show that if you already have high blood pressure, lowering your salt intake could benefit you by a reduction in blood pressure of 3.6/1.6mmHg.(7) Unfortunately, this minimal improvement in blood pressure will actually ramp up compensatory mechanisms that compromise your health, as your body attempts to preserve this essential mineral.
Consequences of Low-Salt Diet
What happens when you restrict sodium intake in your diet? A chronic lack of salt triggers a few important survival mechanisms in the body. First, your kidneys increase sodium retention (and reduce excretion) via the renin-angiotensin-aldosterone system in an effort to conserve salt, which may even increase your blood pressure.(8) Second, your sympathetic nervous system gets activated, increasing your heart rate four to five beats per minute.
This is due to the adrenaline release that constricts your arteries as your blood volume goes down, requiring your heart to pump harder to meet the demands. This places additional "stress" on your heart and arteries, and makes you more susceptible to chronically high blood pressure.
If you have high blood pressure, salt restriction has also been shown to increase inflammatory markers, LDL lipoproteins, triglycerides and total cholesterol to HDL ratio, all reliable markers for poor metabolic health.(9,10). So, the real question seems to be, how much salt should you consume?
How Much Salt Should I Consume?
Expert Dr. James DiNicolantonio suggests you should aim for between 3-6 grams of salt per day, (which equals about 1 1/3 to 2 2/3 teaspoons per day). If you're overweight (or looking to improve your health), eat a standard Western diet high in processed carbs and sugar, you'll likely be getting a very high sodium intake (in the form of refined sodium chloride) with very little potassium. The ratio of sodium-to-potassium is a crucial piece of the puzzle and often overlooked by doctors who tell patients to restrict their salt intake.
Research shows good evidence that the “sodium-to-potassium ratio” is a very important metric for vascular health, showing strong associations with blood pressure and cardiovascular disease (versus only addressing individual sodium or potassium levels).(10) Fruits and veggies are naturally very high in potassium and low in sodium, therefore a diet emphasizing these foods (i.e. low-carb, high fat of LCHF diet) will boost potassium levels significantly and promote the right "sodium to potassium" balance. You can still add sea salt to meals, aim for the lower end of 3-6 gram suggestion (1 1/3 tsp per day) and titrate up as you lose weight.
Salt, Athletes and Overtraining
If you’re an avid Crossfitter, runner, or exerciser and eating cleanly – minimal processed foods, snack foods, and convenience foods – then chances are you are not getting enough salt. You should aim for the upper end of salt range, toward 5-6 grams per day.
Intense exercise in the gym or training outdoors can lead to significant sweat loss - ranging from 500 to 1,200mg of sodium loss per hour - and the typical sports drink only provides about 300mg of sodium per 500mL If this persists for too long, you can develop symptoms of over-training due to low sodium status. (This is especially important if you follow a low-carb or keto approach).
Low salt status can hamper your training by impairing muscular strength and work capacity due to low sodium levels increasing the acidity of your cells.(12) Not only that, your cells that produce cartilage (called chondrocytes) required adequate amounts of sodium to work properly and repair your connective tissue. Thus, low-salt diets can worsen joint health.
The problem is very difficult to pick-up with traditional medical diagnostics, as the blood levels of sodium will typically remain in the normal range despite the athlete experiencing symptoms of sleep disruption, low mood, and increased thirst and urination — all common symptoms in over-trained athletes. If your blood levels are low, the medical condition is called hyponatremia and it can be very serious (even fatal), so be sure to seek medical attention if you feel light-headed, faint or vomiting during training or competition.
If you're training intensely consume salt approximately 2,300mg of salt per litre during exercise.(13) Also, remember to add a variety of sea salts (see below) liberally to your food to increase recovery and support overall health. If you train in warmer weather, this becomes even more important.
Table Salt vs. Sea Salts
So, what type of salt is best? Regular old table salt, sea salt, or the fancy salts from the Himalayan mountains? Table salt only contains two minerals - sodium and chloride - and is also heavily processed, devoid of important trace minerals, and contains harmful anti-caking additives like sodium silicoaluminate. Table salt does however contain iodine, lost during intense training and critical for healthy thyroid function.
Sea salts or Himalayan pink salts naturally contain 50-70+ essential trace minerals and are far superior to add to your diet to improve health and performance. Redmand salt from Utah contains the greatest concentration of iodine amongst the sea salts, while Himalayan salt is highest in potassium, Hawaiian Black Salt rich in iron and Celtic salts highest in magnesium. (Note - If you struggle with low iodine, your diet should provide the bulk of your iodine intake via seaweed, kelp, etc.)
Salt is essential for health (not an evil additive). As a general rule, aim for 3-6g of sodium per day. If you're out of shape and trying to lose weight, aim for the lower end of the range as low-salt diets can hinder insulin sensitivity and health. For active people. you can be more liberal with your salt intake to offset sweat, support performance and recovery. Remember, too much salt is seldom the problem for most people. Natural sea salt in the form of Himalayan, Celtic, Redmands, Hawaiian, etc is crucial for your overall health, performance and recovery... And it tastes great!
Dr. Marc Bubbs ND, MSc, CISSN, CSCS
ps. Listen to my interview with Dr. James DiNicolantonio PhD as we talk salt, health and performance.
REFERENCES
1) Eaton S et al. Paleolithic Nutrition. A consideration of its nature and current implications. N Engl J Med 312(5):283-289.
2) O’Donnell M et al. Urinary sodium and potassium excretion, mortality, and cardiovascular events. N Engl J Med. 2014 Aug 14;371(7):612-23. doi: 10.1056/NEJMoa1311889.
3) Garg R et al. Low-salt diet increases insulin resistance in healthy subjects. Metabolism.2011 Jul;60(7):965-8. doi: 10.1016/j.metabol.2010.09.005.
4) Bayer R et al. Salt and public health: contested science and the challenge of evidence-based decision making. Health Aff (Millwood) 31(12):2738-2746.
5) Overlack A et al. 1993. Divergent hemodynamics and hormonal responses to varying salt intake in normotensive subjects. Hypertension. 22(3):331-338.
6) http://www.worldlifeexpectancy.com/cause-of-death/coronary-heart-disease/by-country/
7) Graudal N, et al.. Effects of low-sodium diet vs. high-sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride (Cochrane Review). Am J Hypertens. 2012 Jan;25(1):1-15. doi: 10.1038/ajh.2011.210.
8) Kitchen T et al. Baroreceptor sensitivity in prehypertensive young adults. 13 (6 Pt 2):878-883.
9) Nakandarkare et al. 2008. Dietary salt restriction increases plasma lipoprotein and inflammatory marker concentration in hypertensive patients. Atherosclerosis. 200(2):410-416.
10) Harsha et al. Effect of dietary sodium intake on blood lipids: results from the DASH-sodium trial. Hypertension 43(2):393-398.
11) Perez V, Chang E. Sodium-to-potassium ratio and blood pressure, hypertension, and related factors. Adv Nutr. 2014 Nov 14;5(6):712-41.
12) Blank M et al. Total body Na(+) depletion without hyponatremia can trigger overtrading-like symptoms with sleeping disorders and increasing blood pressure: explorative case and literature study. Med Hypotheses 79(6):799-804.
13) Sharp. Role of sodium in fluid homeostasis with exercise. 231S-239S.