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Salt is a staple that, for centuries, served as a form of currency, as attested to by the word “salary”: the salarium of Roman legionnaires was paid in salt. The kings of France went on to use this essential commodity to enrich themselves by collecting a salt tax. The salt market has long been an important economic driver. Before people had fridges at home, salt was used to preserve food.
Today, the problem has shifted toward the growing number of high-salt processed foods, which has led to an average per capita salt consumption of over 5 g per day. In some developing countries, daily salt intake is between 9 g and 12 g, half of which comes from fewer than a dozen popular processed foods. The reasons salt is added to so many foods? Flavour, texture and preservation. White bread may be yummy, but it contains a ton of salt!
Salt presents a major health risk in that it’s our main source of sodium
While “salt” and “sodium” are often used interchangeably, they’re not the same thing: table salt is sodium chloride, of which 40% is sodium. To simplify the calculation: 1 teaspoon of salt weighs 6 g and contains 2,400 mg of sodium. And guess what? This quantity exceeds Health Canada’s Tolerable Upper Intake Level (UL), which is a measure of the quantity that poses a health risk.
For people 14 to 50 years of age, the UL for salt is 2,300 mg per day. But keep in mind that this limit indicates the danger zone and not the recommended daily allowance (RDA) or Adequate Intake (AI), which is around 1,500 mg per day. The Adequate Intake drops to 1,300 mg as of age 51, and then to 1,200 mg as of 70. The World Health Organization (WHO) recommends a daily salt intake of less than 5 g, or 2,000 mg of sodium.
Statistics indicate the extent to which our diet exceeds these standards. In Canada, over 85% of men, and 60% to 80% of women, consume more than the Tolerable Upper Intake Level of salt on a daily basis. As a result, 30% of hypertension cases are directly related to salt consumption. Studies have shown that by cutting salt intake in half, one million Canadians would no longer have high blood pressure, the number of people with controlled hypertension would double, and the healthcare system would save $430 million on hypertension treatments alone. That’s a nice chunk of change that could be put to better use!
Now that you know how much salt to consume each day, you might want to know why we need it in the first place.
First of all, whatever you do, don’t go trying to cut sodium out of your diet! That would be impossible because basic foods like fruits and vegetables naturally contain sodium. Next, your body absolutely needs sodium to maintain normal cell function, nerve impulse transmission, muscular activity, acid/alkaline (pH) balance, and the volume of plasma (blood’s liquid component). Potassium plays an equally important role in these functions and its action is intimately linked to sodium’s. As for sodium, it plays a role in the absorption of nutrients by the intestinal cells.
So what does this have to do with hypertension? “Tension” is the pressure exerted on the walls of veins and arteries, the same way water exerts pressure on the walls of a garden hose. The term “hypertension” (or high blood pressure) is used when the blood exerts too much pressure on blood vessel walls, while also putting additional strain on the heart, which damages the arteries and reduces their elasticity.
The physiological process that links sodium to the development of hypertension is complex, but this causal link has been proven countless times: increased salt intake leads to higher blood pressure. This is due to the fact that the kidneys can’t eliminate all excess salt and their ability to eliminate salt declines with age.
Potassium, or more accurately, the sodium/potassium ratio, is another factor. The combination of too much sodium and not enough potassium has a harmful effect on blood pressure. Studies have shown that a diet rich in potassium mitigates the blood pressure increase caused by sodium.
In addition to increasing blood pressure, excessive salt consumption is also associated with a higher risk of obesity, stomach cancer, osteoporosis and kidney stones. It has even been found to aggravate asthma symptoms. Conversely, lower salt consumption reduces the risk of other cardiovascular diseases such as strokes.
So where is all this dietary salt hiding?
In my home, there’s no salt shaker on the table, but if I’m not careful to check how much sodium I’m getting in the foods I eat, I can easily exceed the Upper Intake Level.
Health Canada has compiled a list of the main sources of dietary sodium. The biggest culprits are (drum roll please): breads, quick breads and related product (14%), processed meats (9%), and ready meals and vegetable juices (7%).
You have to be careful because some of the saltiest foods, like sauces (soy, barbecue, fish (nuoc mam), etc.), broths and processed meats (bacon, ham, salami), contain huge quantities of sodium, though we tend to eat much smaller amounts of them than we do things like bread.
If your slice of bread contains 300 mg of sodium and you have two slices a day, you’ve already eaten a third of your Adequate Intake—it goes up fast! I checked my favourite white bread and, to my dismay, it contains a whopping 370 mg per slice. So consider opting for breads that contain less than 100 mg of sodium per slice.
To improve the sodium/potassium ratio, make sure to include potassium-rich foods in your diet. These include:
- pulses (legumes)
- rye bread
- cottage cheese (which unlike most cheeses is low in salt
- fruits: apricots, bananas, cantaloupe, honeydew melon, figs, dates, mangoes and nectarines;
- vegetables: artichokes, avocados, beets, Brussels sprouts, potatoes, mushrooms, okra, kohlrabi, Chinese cabbage and turnips.
Another way to improve the ratio is to replace salt with a salt-free seasoning containing potassium chloride, another kind of salt, instead. But keep in mind that it can only be used for cooking. It has the dual advantage of reducing sodium while increasing potassium.
For cooking, you can also season with spices and herbs instead of salt or other high-sodium seasonings (monosodium glutamate, soy sauce, etc.).
In addition to reducing sodium intake, you can take other steps to promote healthy blood pressure:
- Quit smoking
- Maintain a healthy weight
- Limit your alcohol intake (maximum two standard portions a day)
- Get 30 to 60 minutes of exercise every day if you can
- Eat healthy, starting with 8 to 10 portions of fruits and vegetables a day
If your taste buds protest when you cut out salt, just remind yourself that they’ll adapt in time and in the end you’ll be amazed to find that you can perceive a wider range of flavours.
https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/sodium.html Can J Cardiol. 2007 May 1;23(6):437-43.