Nancy Churnin / The Dallas Morning News

Salt and sugar — they look so harmless, so basic, so essential. Yet the rapid increase in their presence in everything from canned soups to frozen meals and yogurt snacks worries medical experts.

Dr. Arash Tirandaz, an internist on the medical staff at Texas Health Presbyterian Hospital Plano, tells his patients that cutting down on sugar and salt is one of the best ways to improve their health.

“Too much sugar can cause insulin resistance, obesity and diabetes,” Tirandaz said. “Salt can cause water gain and high blood pressure, which can lead to heart failure, heart attack and stroke.”

The studies and books that make this point keep multiplying. The World Health Organization recommended global goals for reducing salt to lower blood pressure in January. The BMJ Group, a provider of medical information and services owned by the British Medical Association, cited new studies in April supporting that effort; Britain has already undertaken a national effort to reduce salt. A recent study in Nature also explores a link between salt and autoimmune diseases such as multiple sclerosis in mice.

Last year, Dr. Robert Lustig, a pediatric endocrinologist at the University of California, San Francisco, elaborated on his thesis that sugar is a toxic substance that causes metabolic syndrome and fatty liver disease in “Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease” (Hudson Street Press, $25.95).

The majority of salt and sugar we consume is in processed and restaurant foods, according to the Centers for Disease Control and Prevention. Current guidelines advise adults to consume no more than 2,300 mg of sodium, or about a teaspoon of salt, per day and no more than 1,500 mg daily, or ¾ teaspoon of salt, if you are 51 or older, are black, or have high blood pressure, diabetes or chronic kidney disease.

The American Heart Association recommends limiting added sugar to no more than 100 calories per day (about 6 teaspoons or 24 grams of sugar) for women and no more than 150 calories per day (about 9 teaspoons or 36 grams of sugar) for men; the Harvard School of Public Health notes, however, that your body doesn’t need any carbohydrates from added sugar.

Many Americans exceed what they should consume of both substances, the CDC reports. Part of the reason is that many might not realize how omnipresent sugar and salt are in popular products on grocery shelves, as Michael Moss points out in his new book, “Salt Sugar Fat: How the Food Giants Hooked Us” (Random House, $28).

“They’re so dependent on these three ingredients,” Moss said of food manufacturers. “It goes far beyond the amount we should be eating.”

Speaking on the phone from The New York Times, Moss, a Pulitzer Prize-winning investigative reporter, says one of the reasons that salt has become so pervasive is that it is a cheap preservative that allows the product to last longer, mask bad flavors and be sold for less money. Sugar helps sell foods because it makes the taste of food and drink “irresistible,” he said.

He describes a world of food scientists, many too smart to eat their own products, adjusting levels of sugar and salt to find the “bliss point” for consumers.

Marketers have become increasingly clever with labels, too, he says. Half a cup of one name-brand organic minestrone has 580 mg of sodium. Similarly, shoppers may pick up a low-fat yogurt, not realizing that some servings of certain brands have more sugar than ice cream.

Some of the experts he interviewed, including Paul Breslin, a geneticist, biologist and professor in the department of nutritional sciences at Rutgers, the State University of New Jersey, suggest that salt and sugar behave like narcotics, making them hard to shake.

“Ultimately whatever you eat ends up in your blood, and our body wants the blood levels for everything — from carbon dioxide to oxygen to salt and potassium and lipids and glucose — to be constant,” his book quotes Breslin as saying. “This is exactly what happens when you take drugs. When you inject heroin into your body, your body says, ‘Holy cow, what have you done to me?’ It has to try and metabolize these things, and there’s all kinds of coping mechanisms for that.”

Dr. Carolyn Matthews, director of integrative medicine at Baylor University Medical Center, says she’s seen “phenomenal results” in her patients’ health when they change their eating habits.

Reducing sugar and salt, she says, “may not have as dramatic effects as pharmaceuticals, but they have pleiotropic (multiple) effects, particularly with chronic diseases. There are only upsides.”