When I began working in Papua New Guinea in 1964, the vast majority of the population still lived largely traditional lifestyles in their villages.
Among the many things that impressed me about New Guineans was their physical condition: lean, muscular, physically active — all of them resembling slim western body builders.
During those early years in New Guinea, I never saw a single obese or even overweight New Guinean. The non-communicable diseases that killed most first-world citizens today — diabetes, stroke, heart attacks and cancers — were rare or unknown among traditional New Guineans living in rural areas.
But, already in 1964, the killers of first-world citizens were beginning to make their appearance in New Guinea among those populations that had had the longest contact with Europeans.
Today that westernization of New Guinea diets, lifestyles and health problems is in a phase of explosive growth — in cities, towns and westernized environments — one commonly sees overweight or obese New Guineans.
These changes that I’ve been watching unfold are just one example of the wave of epidemics of non-communicable diseases (NCD) associated with the western lifestyle and now sweeping the world. Major NCDs in the current wave include various cardiovascular diseases, heart attacks, strokes and peripheral vascular diseases, the common form of diabetes, some form of kidney disease, and some cancers such as stomach, breast and lung cancers. The vast majority of us will die of one of these diseases. All of these NCDs are rare or absent among small-scale societies with traditional lifestyles. While the existence of some of these diseases is attested already in ancient texts, they became common in the West only within recent centuries. Of course I’m not suggesting that we adopt a traditional lifestyle wholesale. Instead our goal is to identify and adopt particular components of that lifestyle that protect us against non-communicable diseases. While a full answer will have to wait for more research, it’s a safe bet that the answer will include traditional low salt intake. Today, salt is cheap and is available in essentially unlimited quantities. Our bodies’ main problem with salt is to get rid of it, which we do copiously in our urine and in our sweat. The average daily salt consumption around the world is about 9 to 12 grams. Traditionally though, salt didn’t come from salt shakers but had somehow to be extracted from the environment. Our main problem with salt then was to acquire it rather than to get rid of it.
That’s because most plants contain very little sodium, yet animals require sodium at high concentrations in all their extracellular fluids. As a result, while carnivores readily obtain their needed sodium by eating herbivores, full of extracellular sodium, herbivores themselves face problems in obtaining that sodium.
That’s why the animals that you see coming to salt lakes are deer and antelope, not lions and tigers. For dozens of traditional hunter gatherers whose daily salt intake has been calculated, it falls below 3 grams, the lowest recorded value is for Brazil’s yanonami Indians whose staple food is low sodium bananas and who excrete on the average only 15 mg of salt daily, about 1 – 2/100 of a salt excretion of the typical American. A single Big Mac hamburger analyzed by consumer reports contained 1.5 grams of salt representing one month’s salt intake for a yanonami.
As a result of the relatively recent adoption of a high salt diet by our still largely traditional bodies adapted to a low salt diet, high salt intake is a risk factor for almost all of our modern non-communicable diseases. Many of the damaging effects of salt are mediated by its role in raising blood pressure. High blood pressure is among the major risk factors for cardiovascular diseases in general and for strokes, congestive heart disease, coronary artery disease and myocardial infarcts in particular, as well as for type-2 diabetes and kidney disease. In at least 4 countries, notorious for high average level of salt consumption and resulting stroke deaths — China, Finland, Japan and Portugal — government public health campaigns that lasted years or decades achieved local or national reduction in blood pressure and in stroke mortality.
For instance, a 20-year campaign in Finland to reduce salt intake succeeded in lowering average blood pressure and thereby cut 75 or 80% off of death from strokes and coronary heart disease and added 5 or 6 years to Finnish life expectancies. If by now you’re convinced that it would be healthy for you to decrease your salt intake, how can you go about it?
Only about 12% of our salt intake is added in the home and with our knowledge, either by whoever is cooking or by the individual consumer at the table. The next 12% is salt naturally present in the food when it’s fresh. Unfortunately, the remaining 75% of our salt intake is hidden. It comes already added by others to food that we buy, either processed food or else restaurant food to which the manufacturer or the restaurant cook respectively added the salt.
As a result, Americans and Europeans have no idea how high is their daily salt intake, unless they subject themselves to 24-hour urine collections. Abstaining from the use of salt shakers doesn’t suffice to lower drastically your salt intake. You also have to be informed about selecting the foods that you buy and the restaurants in which you eat. Processed foods contain quantities of salt impressively greater than the quantities in the corresponding unprocessed foods. For instance, compared to fresh unsalted steamed salmon, tinned salmon contains 5 times more salt per pound, and store-bought smoked salmon contains 12 times more. Why do manufacturers of processed food add so much salt? One reason is that it’s a nearly costless way to make cheap unpalatable food edible.