One of the more controversial studies we reported on this year on Quirks & Quarks was about the latest science on the health risks of eating red and processed meat.

The study raised strong objections from some, but others praised its rigour and suggest it is a milestone and could guide the way forward as the we more critically evaluate the quality of nutritional science studies.

Scientists conducted five systematic reviews and meta-analyses and published them this fall in the journal Annals of Internal Medicine. They concluded that eating moderate amounts of red or processed meats poses a "very small" risk to our health.

The system the scientists used in those studies is a standard many experts believe should widely adopted as a way to wade through the flip-flopping headlines about nutritional research.

"A fundamental problem with nutrition science for decades has been that we've relied on a very weak kind of science," Nina Teicholz, told Quirks & Quarks host Bob McDonald. Teicholz is a science journalist and executive director of the Nutrition Coalition — a non-profit organization that doesn't accept industry funding,

It's a little bit like we've been playing a game of soccer with no referees. - Nina Teicholz, Nutrition Coalition

Nutritional advice often comes from observational studies that show associations between some foods and health outcomes. Many critics say these studies can be unreliable. For one thing it can be hard to tease out the effect of lifestyle factors from the health outcomes. The studies are also often based on surveys that ask people about their diets, and it can be difficult for people to accurately recall and report what they've eaten.

"When you test these weak associations in a proper rigorous clinical trial, it turns out those weak associations are only shown to be correct zero to 20 per cent of the time," added Teicholz.

Systematically assessing study quality

"The red meat studies were really a milestone," said Teicholz. She added that the system those scientists used for grading nutritional studies "really brings discipline to the field that it has not had in the past."

"It's a little bit like we've been playing a game of soccer with no referees."

The scientists who conducted the meat studies used a system known as GRADE to prioritize strong science over weak science. An observational study would be graded lower than a randomized, controlled trial and strong associations graded higher than weak associations.

"[GRADE] was recommended by the National Academy of Sciences for the use of our U.S. dietary guidelines. So that's the highest recommendation in the land for our most important nutrition policy," said Teicholz.

"I think that the future of nutrition [science] will include GRADE," she added.