Table of Contents
- Sodium and Health
This post is dated 2018. It has been written to be updated.
Salt (sodium chloride) is a chemical agent used to cook or process food. Saltiness is regarded as one of 5 main tastes. (Scientists have not, as of 2018, identified a distinctive taste receptor for salt.) Sodium is an essential nutrient, but consuming more sodium than the minimum has no health benefits.
Mark Kurlansky’s excellent book Salt: a World History (2002) tells of the uses of salt to brine or pickle soybeans and vegetables in China (>700 BCE), to cure hams by the Celts (Gauls and Germans) and Romans (>100 BCE), the fermentation of fish to make Garum (Greek, Phoenician, Meditaranean, Roman fish sauce >900 BCE ) and oriental fish sauces ( China >2000 BCE ). The production of salt may have started about 8,000 years ago. Until the invention of canning and refrigeration, salt was used to preserve food. Salt was and still is used to control or kill bacteria or yeast to preserve food (salting, cure, brine or pickle). Some foods were to heavily salted they had to be soaked to make them palatable. Salt is use also to manage the activity of “good” yeast and bacteria.
Food processing includes:
- harvesting, drying & milling raw plant products including grain, beans, vegetables and fruit;
- raising, slaughtering and butchering animals;
- processing agricultural products to commodies used to “make” food – e.g. flour, powder and syrop;
- combining processed commodities to manufacture food product including products that can be served after adding water, or warming them with appliances;
- packaging a product for transportation and sale
- (pre)cooking food into heat and serve meals.
Sodium and Health
Sodium is an essential nutrient but excessive sodium consumption is a health risk.
The upper limits for sodium intake, in milligrams, per day:
- US Department of Agriculture & Department of Health – Less that 2,300 mg. for an adult in the general population; less than 1,500 mg. for a person with hypertension, or over 50:
- American Heart Association – less than 1,500;
- World Health Organization – less than 2,000 (or 5 grams of salt):
- Canada Department of Health Tolerable Upper Intake Level, 2,300.
These numbers are not stated in ranges for body type, or weight. The limits are stated as a single number for an “average” adult and a second, lower number for persons diagnosed with hypertension, or defined by age or other statistical risks. The 2,300 milligram figure is the sodium in 5,700 mg. (5.7 grams) of salt – about a teaspoon (the unit of volume). Exceeding the upper limit is risky and harmful.
Other sodium compounds added to processed food: sodium bicarbonate, sodium citrate, sodium phosphates, sodium pyrophosphate, monosodium glutamate.
Salt, Sugar, Fat
Processed foods used chemical additives – for instance as a binding agents – e.g. to make starch and water into a pudding. In Salt, Sugar, Fat (2013), investigative journalist Michael Moss looked at those ingredients as additives, and at aspects of the food industry:
- financial and market constraints; investor and corporate governance
- selling more product is the main goal;
- input costs are already controlled; the costs of getting goods in front of customers is the main production cost,
- marketing and social engineering:
- the quasi-science of flavour,
- consumer expectations: convenience, flavour, texture;
- product development and financial engineering:
- the business strategy of putting new products into the market;
- product line extensions;
- the politics of getting the food industry to state the contents of its products.
Michael Moss reported on his interviews with personnel at Cargill, a major supplier of salt to the food processing industry in his 2010 New York Times article “The Hard Sell on Salt” and in Salt, Sugar, Fat. Without salt:
- The Cheez-It was not palatable. The colour faded. The crackers became sticky when chewed, and the mash packed onto the teeth. The taste was medicinal;
- Corn Flakes tasted metallic;
- Eggo waffles evoked stale straw;
- The butter flavor in the Keebler Light Buttery Crackers, which have no butter, disappeared;
- Many products, including meat products, develop what food industry people called Warmed Over Flavour, described as cardboard or damp dog hair.
Salt, Sodium and Public Heath
Public health campaigns in the 1980’s concentrated on avoiding sprinking salt on prepared food by the (with a salt shaker/salt grinder). Then public agencies set limits and compelled food processors to put salt on product labels. Disclosure of sodium in product labels for processed foods is required by law in North America and Europe. Campaigns moved on to changed limits, better labels, more information, labels on menus, etc.
The food industry wants to identify whatever it produces and sells as safe, nutritious, and authentic or wholesome. The food industry considers labelling and public health information represents the foot of government on the throat of free enterprise. In part it promotes scepticism about the science that says excess salt is bad. Michael Moss looked resistance from food manufacturers and processors in the Salt section of his book Salt, Sugar, Fat. Marion Nestle has provided commentary on the Food Politics web site. (Search Salt in the search bar or search for posts tagged Salt). Scientific American published one article in July 2011 “It’s Time to End the War on Salt” discussing the inconclusiveness of clinical trials. A week later, Scientific American published an inteview with Marion Nestle who said:
But if you do a clinical trial where you try to put large amounts of people on a low-salt diet, you just don’t see much difference between the people who say they eat a lot of salt and the people who say they don’t eat a lot of salt. In clinical trials the relationship doesn’t show up. Two reasons: One that it’s impossible to put a population of people on a low-salt diet. Roughly 80 percent of the salt in the American food supply is in foods before people eat them—either in processed food or in restaurant food. Because so much salt is added to the food supply and because so many people eat out, it’s impossible to find a population of people who are eating a low-salt diet. They basically don’t exist.
… There’s a proportion of people in the population who are sensitive to salt—if you lower their intake of salt, then their blood pressure goes down. There’s another (probably larger) percentage of the population who doesn’t respond. They are people who can eat as much salt as they want and still their blood pressure is low. So you have this curious anomaly where whenever you do a clinical trial you get these complicated, difficult-to-interpret results that don’t show much of an effect. But everybody who works with patients who have hypertension think they do better [on a low-salt diet].Scientific American, July 14, 2011, The Salt Wars Rage On: A Chat with Nutrition Professor Marion Nestle
The food industry has created some products that are made without adding salt and other sodium compounds. It’s a niche – another diet option. “Healthy” (whole grain, high fiber, low-fat, and organic) products often are as salty as anything else, or more (e.g. low-fat mayonnaise in a product line may have 150-200% the sodium of the regular mayonnaise). Reduced” or “low” sodium statements by manufacturers are generally mere puffery. “No added sodium” generally means no sodium, but not always.
Living without salt means learning to taste differently. It does not mean that everything is going to be bland. People get habituated to the amount of salt they normally consume:
A group of young adult subjects was placed on self-maintained, low sodium diets for 5 months. Taste responses to salt in solutions, soups, and crackers were determined both during the 2 months preceding diet initiation and during a 5-month period when subjects lowered their sodium intake. Taste responses were also determined in a control group with ad libitum salt consumption throughout the same period. Perceived intensity of salt in crackers increased. The salt concentrations of maximum pleasantness in soup and crackers fell in the experimental subjects but not in the control subjects. These results demonstrate that the preferred level of salt in food is dependent on the level of salt consumed and that this preferred level can be lowered after a reduction in sodium intake. The implications of these findings for the maintenance of low sodium diets are discussed.Bertino, Beauchamp & Engelman The American Journal of Clinical Nutrition, Volume 36, Issue 6, 1 December 1982, Pages 1134–1144
Also “Effect of dietary sodium restriction on taste responses to sodium chloride: a longitudinal study”, The American Journal of Clinical Nutrition, Volume 44, Issue 2, 1 August 1986, Pages 232–243
High Sodium Foods
Food products high in sodium:
- Sandwich spreads, condiments and salad dressings;
- Processed meat, cold cuts, charcuterie;
- pickles, olives,.
- Processed (flaked/puffed or shaped and toasted) breakfast cereal;
- Tomato juice, vegetable juice and tomato-clam (some very high);
- Processed spaghetti sauces and tomato sauces (very high);
- Pizza – bread topped with tomato sauce, cheese, and whatever else (most very high);
- Canned soups (monstrously high);
- Soy sauce, hoisin sauce and fish sauce; miso paste (monstrously high).