Other than saturated fat, I can’t think of a nutrient that’s been so universally maligned and demonized as salt. All the experts hate it and recommend that we get as little of it as possible. They even all seem to have their own little anti-salt slogans. The American Diabetes Association recommends between 2300 and 1500 mg of sodium per day (“Be Sodium Savvy“). The American Heart Association wants you eating less than 1500 mg per day (“Shaking the Salt Habit“) and claims that 97% of young people already eat way too much salt. The other ADA – the American Dietetic Association – also recommends between 2300 and 1500 mg, but their slogan is far inferior (“Slice Your Sodium Intake“). It’s quite the pile-on, isn’t it?
Why does salt strike mortal terror into the hearts of so many?
Back in the 1980s, a massive global study of salt intake and blood pressure called INTERSALT was undertaken. Overall, it showed a modest association between the two, but some groups, particularly the undeveloped, non-industrial peoples who had very little access to salt (and other trappings of industrialization), had blood pressure that was generally extremely low. Foremost among these groups were the Yanomami of the Amazon rainforest. The Yanomami have very low sodium excretion, which indicates very low sodium intake, and very low blood pressure. Even the elderly Yanomami enjoyed low blood pressure. This was convincing. I mean, it sounds convincing, right? Low salt intake, low lifelong incidence of hypertension – how much more cut and dry can you get? This low salt/low blood pressure connection seemed to also apply to other groups who happened to be living more traditional ways of life.
Except that there’s another non-industrialized group (and you only need one) whose slightly different results kinda muck up the Yanomami argument: the Kuna of Panama.
Among the Kuna, a tribe native to Panama, both salt intake and blood pressure were also historically low well into old age. To study whether the two variables were linked, researchers examined a group of “acculturated” Kuna with ample access to salt and an otherwise strict adherence to their traditional way of life. Little changed but the salt intake, in other words. But, despite consuming an average of 2.6 daily teaspoons of salt (and sometimes up to 6 teaspoons), the Kuna did not have hypertension, not even in old age. There was no change between the hypertensive statuses of 20 year old Kuna and 60 year old Kuna.
All in all, drastic reduction of sodium can reduce blood pressure by a few points. The evidence is pretty consistent on that. But the example of the Kuna shows that there’s way more to blood pressure than how much salt you eat, like how much potassium you eat.
Consider two recent Cochrane meta-analyses. The first, on sodium restriction and blood pressure, found that for people with hypertension the mean effect of sodium restriction was -5.39 mm Hg for systolic blood pressure and -2.82 mm Hg for diastolic blood pressure. In normotensive people, the figures were -2.42 mm Hg and -1.00 mm Hg, respectively. Decent reductions, I suppose, but what about potassium and blood pressure?
The upper intake of potassium was associated with over a 7-point drop in systolic blood pressure and a 2-point drop in diastolic blood pressure, but only in people with hypertension (the people who actually should lower blood pressure). Unfortunately, the official recommendations for sodium and potassium intake cannot be met simultaneously. Yep – the experts want you to eat in a way that is literally impossible to accomplish. Inspires confidence, doesn’t it?
Let’s forget about blood pressure for a second, because there’s also way more to health than the meager drops in blood pressure afforded by sodium restriction. Recent evidence suggests that for many people, all out salt reduction has an overall negative impact on several other aspects of health:
In 2011, one study showed that seven days on a low salt diet increased insulin resistance in healthy men and women when compared to a higher-salt diet.
Another study showed that while reducing salt moderately improved the blood pressure of hypertensive patients by a mere 4.18 and 1.98 points for systolic and diastolic, respectively (but not of people with normal blood pressure), it also had negative effects on multiple other health markers, including increased triglycerides and LDL and elevated stress hormones.
Another 2011 study found that eating a low salt diet (under 3 grams of sodium per day, or just over a teaspoon of salt) and a high salt diet (from 6-7 grams of sodium per day, or well over two teaspoons of salt) both increased the risk of stroke and heart attack, while eating between four and six grams of sodium, or about two teaspoons of salt, each day was associated with the lowest risk of cardiovascular incidents.
A recent study found that salt intake followed a J-curve, with low and high intakes increasing arterial plaque formation and a medium intake decreasing it.
Sodium depletion due to “low-sodium nutrition” has been shown to trigger overtraining-like symptoms, including hypertension and sleeping disorders.
The greatest health marker of all – being alive – also has an interesting association with salt intake. It seems that, time and time again, folks with a “medium” salt intake live longer than people who eat too little salt or too much salt. That amounts to roughly 4000 mg of sodium, or close to two teaspoons of regular salt.
Sodium intake affects other markers of vascular health beyond just blood pressure, too:
Greater sodium excretion in the urine (a common marker of sodium intake) may be positively associated with large arterial compliance. Large arterial compliance is a measure of arterial elasticity, or the ability of one’s arteries to handle fluctuations in pressure. Stiffer arteries are more prone to damage.
Low sodium status (whether dietarily-induced or caused by increased sodium loss) can also increase aldosterone, an adrenal hormone that seeks to preserve sodium in the body when it’s perceived to be scarce. High aldosterone levels are associated with insulin resistance, and aldosterone blockers are being explored as potential treatments of vascular disease and hypertension.
Well, what is salt good for?
That question honestly isn’t asked very often in the literature, but we can surmise some of the benefits just by looking at what happens in people on a low-sodium diet. If that connection persists, then adequate (not excess) salt probably helps prevent some of those problems, like insulin resistance, plaque formation, increased stress hormones, worsened blood lipids, and elevated aldosterone.
There are, however, outright positive effects of salt consumption, too:
Salt supports hydration, especially during exercise.
Of the electrolytes, potassium gets all the attention, even though sodium is just as important. Studies show that sodium loading before exercising in the heat increases fluid volume and reduces the physiological strain of the subsequent training. In other words, consuming sodium before training “involved less thermoregulatory and perceived strain during exercise and increased exercise capacity in warm conditions.” You can workout harder, longer, and more effectively with sufficient sodium in your diet. Salt loading also boosts performance in thermoneutral conditions, not just hot weather.
I remember drinking so much plain water during one race that I actually became dehydrated from pissing out all my electrolyte stores and almost passed out. From that point on, a few teaspoons of salt would solve the problem and prevent it from occurring again. The much ballyhooed bananas didn’t do it. Only pure, unmitigated salt did the trick. Hardcore ketogenic athlete/doctor Peter Attia does the same with his bullion cubes, which he credits for maintaining his performance.
Salt may help you cope with stress.
This is a guess on my part, based on several lines of evidence. First, salt has been shown to speed up cortisol clearance from the blood. The faster you clear cortisol, the quicker you recover from a stressor. If cortisol lingers, you “stay stressed.”
Second, there’s evidence that stress increases salt appetite. In lab mice, activation of the sympathetic nervous system by a stressor causes them to prefer salt water to plain water. Similar findings have been observed in rats subjected to stress. In humans, acute bouts of stress don’t seem to increase salt appetite, but chronic stress does increase intake of salty, processed junk food. Obviously, eating McDonald’s fries doesn’t help improve your health, but I find it highly plausible that salting your healthy Primal food to taste could be an important ally against stress. It’s just that when most people need “something salty,” they reach for potato chips, not a couple soft boiled eggs dipped in sea salt.
Third, as I mentioned above, low sodium diets are often associated with elevated stress hormones.
Personally, I’m drawn to salty foods – often jerky or macadamia nuts sprinkled with some sea salt – when I’m up against a deadline, and it seems to help.
It makes food taste better.
Yes, some people would claim this attribute as a negative. Adding salt to food will make you more likely to overeat and gain weight and develop the diseases associated with weight gain and so on and so forth. But I’ve always held that eating good food is one of life’s highest, purest pleasures. If your food doesn’t taste good, there’s no point in eating it. We’re not machines concerned only with fuel. We are sensory, sensual beings with the capacity for appreciation of thousands of flavors. To deny the pleasure of food is to deny our humanity.
Salt can also make otherwise unpalatable – but healthy – food somehow palatable. A plate of steamed kale is boring and bitter. A plate of steamed kale with sea salt and olive oil is delicious and inspiring. Plain broccoli? Kids everywhere are spitting it into napkins and stuffing them into their pockets. Broccoli stir-fried with soy sauce (or tamari, if you please)? Kids everywhere are mailing in their dues (and signing up for auto-pay) for the clean plate club.
You could drop your salt intake to half a teaspoon and get a three or four point drop in your blood pressure. Of course, you might not enjoy your food anymore, your performance in the gym or on the trail would likely suffer, your stress hormones might be elevated, you might start feeling overtrained without doing any actual training, you could become insulin resistant, and you may have trouble clearing (the elevated) cortisol from your blood. But, hey: your blood pressure readings will likely improve by a few points! Or, you could keep your salt intake up around two teaspoons, give or take, simply by salting your food to taste, and avoid all that other stuff.
What do you think, readers? Do you fear salt? Do you relish it? Do you find your salt appetite increases under certain conditions? Let me know in the comment section!