How low can you go?

When it comes to sodium, don't go too low -- because despite what you've heard, too little can be positively deadly.

A new study is shaking up the conventional wisdom on salt, as researchers have found that people who consume "too much" of it actually have the lowest risk of death by heart attack.

And that means those who stick to mainstream low-salt guidelines could be facing big-time risk.

Researchers tracked 3,681 Europeans who did not have hypertension or any other sign of heart problems at the start of the eight-year study.

Then, after measuring 24-hour salt excretion levels at the beginning and end of the study, the researchers divided the volunteers into three groups: low salt (2,500 mg per day), medium salt (3,900 mg) and high salt (6,000 mg).

Going strictly by the guidelines, you might think the people in that last group had a death wish -- that's four times the most recent USDA recommendations!

But the researchers say only 0.8 percent of the patients in that ultra-high salt group died of heart-related causes during the study, versus 4 percent of those with the lowest levels.

In other words, less salt made these people up to five times more likely to die, according to the study in the Journal of the American Medical Association.

So much for the low-salt lifestyle... but in reality, the link between low sodium and heart risk isn't as cut-and-dry as you might think.

Even the American Heart Association, which relentlessly pushes a low-salt diet as a means of combating hypertension, admits they don't know the real cause of 95 percent of all high blood pressure cases.

If you don't understand the cause, how can you possibly pretend to have the solution?

The fact is, there's far more research linking sugar to high blood pressure and poor cardiovascular health than there's ever been for salt.

One study last year found that people who consumed 74 grams of sugar a day -- that's actually less than the U.S. average -- had a 77 percent increased risk of blood pressure readings greater than 160/100.

Once you've cut down on your sugar, increase your potassium. Your body needs about three times as much potassium as sodium -- but most people have that ratio reversed, or worse.

One easy way to get back on track: replace some of your salt with a potassium-based salt substitute.

But don't throw the real stuff away -- because you do need your salt.

Sodium might not be as risky as you've been led to believe, but there's something in your home right now that could be positively deadly.