“knowledge is power.”

Well, today we're going to give you more power

to control your diet and lifestyle

by giving you the facts.

Welcome to the Nutrition Facts Podcast.

I'm your host, Dr. Michael Greger.

Today we continue our series

on how industries impact dietary and health guidelines.

And pick things up by taking a close look

at corporate criticism of scientific nutrition literature.

While randomized controlled trials are highly reliable in assessing

interventions like drugs, they're harder to do with diet.

Dietary diseases can take decades to develop.

It's not like you can give people placebo food,

and it's hard to get people to stick to assigned diets,

especially for the years it would take to observe effects

on hard endpoints like heart disease or cancer.

That's why we have to use observational studies

of large numbers of people and their diets over time

to see which foods appear to be linked to which diseases.

And interestingly, if you compare data obtained from

observational population studies versus randomized trials,

on average, there is little evidence

for significant differences between the findings.

Not just in the same direction of effect,

but of the same general magnitude of the effect

in about 90 percent of the treatments they looked at.

But wait, what about the hormone replacement therapy disparity

I talked about in the last video?

It turns out when you go back and look at the data,

it was just a difference in timing in terms of

when the Premarin was started,

and they actually showed the same results after all.

But even if observational trials did provide lower quality evidence,

maybe we don't need the same level of certainty

when we're telling someone to eat more broccoli or drink less soda,

compared to whether or not you want to prescribe someone some drug.

After all, prescription drugs

are the third leading cause of death in the United States.

It goes heart disease, cancer, then doctors.

100,000 Americans are wiped out every year

from the side-effects of prescription drugs taken as directed.

So, given the massive risks, you better have rock-solid evidence

that there are benefits that outweigh the risks.

You are playing with fire; so, darn right I want randomized

double-blind, placebo- controlled trials for drugs.

But when you're just telling people to cut down on doughnuts,

you don't need the same level of proof.

In the end, the industry-funded sugar paper concluding

that the dietary guidelines telling people to cut down

aren't trustworthy, because they're based on such

“low-quality evidence” is an example of the inappropriate use

of the drug trial paradigm in nutrition research.

You say yeah, but what were the authors supposed to do?

If GRADE is the way you judge guidelines,

then you can't blame them.

But no, there are other tools, like for example, NutriGrade,

a scoring system specifically designed to assess and judge

the level of evidence in nutrition research.

One of the things I like about NutriGrade is that

it specifically takes funding bias into account,

so industry-funded trials are downgraded.

No wonder the industry- funded authors

chose the inappropriate drug method instead.

HEALM is another one,

Hierarchies of Evidence Applied to Lifestyle Medicine,

specifically designed because existing tools

such as GRADE are not viable options

when it comes to questions that you can't fully address

through randomized controlled trials.

In a way each research method has its unique contribution.

In a lab, you can explore the exact mechanisms, RCTs can prove

cause and effect, and huge population studies can study

hundreds of thousands of people at a time for decades.

Take the trans fat story, for example.

We had randomized controlled trials showing trans fat

increased risk factors for heart disease,

and we had population studies showing that the more trans fats

people ate the more heart disease they had.

So, taken together, these studies forged a strong case

for the harmful effects of trans fat consumption on heart disease,

and as a consequence, it was largely removed

from the US food supply, preventing as many

as 200,000 heart attacks every year.

Now, it's true that we never had randomized controlled trials

looking at hard endpoints, like heart attacks and death,

because that would take years of randomizing people to eat

like cannisters of Crisco every day.

You can't let the perfect be the enemy of the good

when there are tens of thousands of lives at stake.

Public health officials have to work

with the best available balance of evidence there is.

It's like when we set tolerable upper limits

for lead exposure or PCBs.

It's not like we randomized kids to drink different levels

of lead and saw who grew up to have tolerable brain damage.

You can't run those kinds of experiments;

so, you have to just pull in evidence from as many

sources as possible and make your best approximation.

“Even if RCTs (randomized control trials) are unavailable or impossible to conduct,

there is plenty of evidence from observational studies

on the nutritional causes of many cancers,

such as on red meat increasing the risk of colorectal cancer.“

So, if dietary guidelines aiming at cancer prevention

were to be assessed with the drug-designed GRADE approach,

they'd reach the same conclusion that the sugar paper did—

low quality evidence.

And so, no surprise a meat- industry-funded institution

hired the same dude who helped conceive and design

the sugar-industry funded study.

And boom, lead author saying we can ignore the dietary guidelines

to reduce red and processed meat consumption,

because they used GRADE methods to rate the certainty of evidence,

and though current dietary guidelines recommend

limiting meat consumption,

their results predictably demonstrated

that the evidence was of low quality.

Before I dive deep into the meat papers,

one last irony about the sugar paper

the authors used the inconsistency of the exact recommendations

across sugar guidelines over a 20-year period to raise concerns

about the quality of the guidelines.

Now obviously, we would expect guidelines to evolve,

but the most recent guidelines show remarkable consistency,

with one exception: the 2002 Institute of Medicine guideline

that said a quarter of your diet could be straight sugar

without running into deficiencies.

But that outlier was partly funded by the Coke, Pepsi,

cookie, candy-funded institute that is now saying see,

since recommendations are all over the place

(thanks in part to us), they can't be trusted.

In our next story, the meat industry comes up

with a perversion of evidence-based medicine.

A series of articles published in the Annals of Internal Medicine

culminated in a recommendation suggesting people

keep eating their red and processed meat.

Nutrition researchers savaged these articles.

The chair of the Nutrition at Harvard called it

“a very irresponsible public health recommendation,”

and the past Harvard Nutrition chair was even less restrained.

“It's the most egregious abuse of data I've ever seen,” said Walter Willett

“There are just layers and layers of problems.”

Let us start to pick through these layers.

First of several serious weaknesses was that the analyses

and recommendations were largely based the so-called GRADE criteria

which I talked about in my last video.

The authors erred in applying the GRADE tool,

since that was designed for drug trials.

GRADE automatically scores observational studies

as “low- or very-low” scores for “certainty of evidence,”

which is exactly what you want

when you're evaluating evidence from drug trials.

You want a randomized double-blind, placebo-controlled trial

to prove the drug's risks and benefits.

However, the infeasibility for conducting randomized clinical trials

on most dietary, lifestyle, and environmental exposures

makes the criteria inappropriate in these areas, since it would involve

controlling people's daily diet and following them for decades.

“You can't do a double‑blinded placebo‑controlled trial

of red meat and other foods on heart attacks or cancer.

“For dietary and lifestyle factors, it's impossible to use

the same standards for drug trials.”

Imagine telling one group of people to smoke

a pack of cigarettes every day for the next 20 years

to prove that cigarettes cause lung cancer.

And how could you make it double-blind,

have the control group smoke placebo cigarettes?

Yet, in the meat papers, they were downgrading studies

due to lack of blinding.

Well duh! In nutrition trials how are you going to blind people

to the fact of what they're eating?

GRADE is just the wrong tool for diet studies.

In fact, the authors admit that the reason