If you're frustrated by the changeable dietary guidelines of late, you're not alone. In the last several years, we've been told to shift our eating habits in some significant ways: Sugar is now a main culprit, linked with chronic disease from cancer to heart attack, while fat seems to be off the hook, even in seemingly high doses.

Results from some large-scale new studies that use data from around the globe don't so much disrupt our current understanding as build upon it. The research confirms that there really needn't be any upper limit on fat, and that carbs should be eaten in moderation and possibly cut down on.

But the studies also add some new information: Namely, that we'd do well in joining the rest of the world in making legumes staples in our diet — and that how we prepare our vegetables may matter for long-term health.

The studies, published this week in The Lancet, looked at data from 135,000 participants taking part in the 10-year Prospective Urban-Rural Epidemiology (PURE) research. The participants lived in 18 countries across the globe: Canada, Sweden, United Arab Emirates, Argentina, Brazil, Chile, China, Colombia, Iran, Malaysia, occupied Palestinian territory, Poland, South Africa, Turkey, Bangladesh, India, Pakistan and Zimbabwe. The PURE study chronicled their dietary habits over the years and tracked long-term health outcomes, including cardiovascular disease and stroke, and mortality. By the end of the study period, about 5,800 people died and 4,800 had non-fatal cardiac events.

In the first study, people who ate the most carbs (i.e., those in the highest quintile, or fifth) had a 28% increased risk of dying from any cause than people who ate the least. Carbs made up 77% of the highest-carb diets vs. 45% of the lowest-carb diets.

But people who ate the most fats (making up about 35% of their diets) had a 23% reduced risk of dying of any cause, compared to people who ate the least (where fat made up about 10%). Most of the difference in mortality risk for both carb and fat consumption was due to non-cardiovascular health problems.

And interestingly, each type of fat was linked to a reduced risk of death: 19% for monounsaturated fat, 20% for polyunsaturated fat, and 14% for saturated fat. This last finding is particularly noteworthy, since adds to a growing body of evidence suggesting that saturated fat isn't the kiss of death, or at least of heart disease, it was once thought to be.

"Our findings do not support the current recommendation to limit total fat intake to less than 30% of energy and saturated fat intake to less than 10% of energy," the authors write. "Individuals with high carbohydrate intake might benefit from a reduction in carbohydrate intake and increase in the consumption of fats." Keep in mind that many Americans may already be consuming considerably more than the amounts of fats in the current study.

Meanwhile, another analysis of the PURE data published in the same journal focused on vegetable, fruit and legume consumption — the legume family, which includes beans, lentils and peas, is a much larger part of people's diets in other parts of the world than it is in North America and Europe.

"[W]e showed that greater fruit, vegetable, and legume intake was associated with a lower risk of major cardiovascular disease, myocardial infarction, cardiovascular mortality, non-cardiovascular mortality, and total mortality," the authors write. The team say that their data suggest that three to four servings of these foods per day conferred the greatest health benefit, and there wasn't much additional benefit above that amount. That's important since five servings are often recommended, but may be hard — and perhaps unnecessary — for people who don't have a lot of money. But not everyone agrees with this interpretation, and critics have suggested that this could be a function of the available data and the very different lifestyle variables of the different populations.

The results also suggest that how vegetables are cooked may matter: Raw vegetables were associated with a slightly lower risk of heart disease and death overall, compared to cooked ones, though some parts of the world don't eat many raw vegetables, so it's again harder to draw conclusions. "Dietary guidelines do not differentiate between the benefits of raw versus cooked vegetables — our results indicate that recommendations should emphasize raw vegetable intake over cooked," said study author Victoria Miller in a statement. The authors acknowledge that cooking boosts the bioavailability of certain nutrients, like lycopene and beta-carotene, so more research will need to be done on this front.

Finally, legumes were linked to a reduced risk of overall mortality and mortality from non-cardiovascular issues. Legumes should definitely get more credit, the authors say — they're great sources of protein, iron, vitamins, fiber