Canadians may want to think twice before putting some extra salt on their mashed potatoes this Thanksgiving.

While salt is an essential mineral the body needs and craves, it also is one of the most hotly debated food additives. It has been linked to heart disease, high blood pressure and even cancer.

A study released this week adds to the salty debate. The long-term study measured adults’ salt intake over a period of one to three years. Dr. Nancy Cook, one of the study’s lead authors, said participants with the highest sodium intake were most likely to die in the post-trial period of about 20 years.

“Low sodium is better. It reduces blood pressure, it reduces cardiovascular disease and it reduces rates of death due to any cause,” Cook, a scientist with the Harvard School of Public Health, told CTV News from Boston.

The study looked at 3,000 people who were put on salt-lowering diets. Over the course of 20 years, scientists found an approximately 12-per-cent lower risk of death for each 1,000 mg cut in salt.

Cook said the lowest death rates were among those who consumed less than 2,300 mg day. On average, adult Canadians consume about 3,400 mg of sodium per day.

But at McMaster University, epidemiology and biostatistics professor Andrew Mente said the research doesn't tell the whole story.

Mente authored a 2016 study that found low-salt diets may not be beneficial and may actually increase the risk of cardiovascular disease. His study only recommended a low-sodium diet for those with hypertension.

"Sodium intake is controlled by the brain, not by public policy. So regardless of sodium content in food, our bodies crave sodium," he told CTV News Channel.

He said only about 20 per cent of people have dangerously high sodium levels, an amount equated to more than 5,000 mg a day.

The rest of Canadians, he argues, are in the optimal level.

“Concentrate on eating an overall healthy diet, exercise, don't smoke and don't worry about a single ingredient like sodium,” he said.

But Cook is not shaken by the opposition. She said her recent study is more accurate than comparable ones because researchers took urine samples over the course of years rather than single-day samples.

She agreed there is room for more research on establishing just how low salt levels can go before becoming unsafe.

“The questions now tend to be related to the lower end of sodium intake,” she said. “Going below 2,300 (mg) is good for you, going further below that, the evidence isn’t really that strong.”

In the meantime, as Canadians prepare their Thanksgiving dinners, she recommends adding less salt rather than cutting it out altogether.

“It’s really easy to do, and once you do lower your sodium, things start to taste more salty,” she said. “Now something salty really doesn’t taste good to me, so you get used to having lower sodium.”

At least 39 countries have established sodium reduction targets, siding with scientists who say salty foods pose more harm than good.

With a report from CTV’s medical expert Avis Favaro