We Know What a Healthy Diet Is. Now Can We Stop Arguing About It?

Eat lean meat, eggs, and seafood, if that's what you want. But remember the bulk of your diet should be vegetables, fruits, whole grains, beans, lentils, nuts, and seeds.

David Katz: I routinely point out that we could eliminate 80 percent of all chronic disease by using what we know. And we don’t do that. We really bog down in bickering about do we know what we know and is this part of what we know more important than that part of what we know. And in no place is that a bigger problem than diet. There’s obviously a lot of money to be made from confusion. Some years ago I worked on air for Good Morning America and I saw firsthand that there really is a vested interest in TV and the media propagating constant change. If you say the same thing about diet on air enough times in a row people lose interest in your dietary segments. If you say something different every time, it’s always interesting. Tune in tomorrow for a new answer. So the media are in on it. The fad diet authors are in on it. Basically a lot of people who just think that their view of the truth through a particular tunnel is the only truth are in on it. But the result is we squander the opportunity to use what we know because we bog down in debate about what we don’t know quite so well. So having completely lost my patience for the status quo, I decided to do something about this. And it’s really challenging now because there was a time not all that long ago when a single voice could rise above the din. Think for example about Dr. [C. Everett] Koop when he was surgeon general. Or Benjamin Spock and the influence that he had on parents raising young children. But that era is gone because we live in the age of the blogosphere and cyberspace and everybody’s got a microphone. And there’s just this incredible amount of static.

And at the end of it all, the answer to the question "Can we say what diet is best for health?" and by health, we mean longevity, vitality, weight control. All the good stuff that we all want. The answer is absolutely no, if what we mean is a very specific, prescriptive — my diet can beat your diet. So, you know, can we say whether the best Mediterranean diet is better than the best vegan diet or that’s better than the best paleo diet for human health? The answer is no. If what we mean, though, by "Can we say what diet is best for health?" is a basic theme of optimal living. Then the answer is a categorical yes. It’s incredibly clear from incredibly voluminous, incredibly consistent literature all around the world, diverse populations, diverse methods, observational epidemiology where you just watch and see what happens. Intervention trials where you assign people to diets. Randomized control trials and real-world experience with large populations like The Blue Zones. And frankly Michael Pollan pretty much nailed this one. Eat food, not too much, mostly plants. That really captures the essence of all of the world’s diets that are associated with good health outcomes. And when I wrote about this with my colleague Frank Hu from Harvard, we said wholesome foods in sensible combinations. And then to put a little meat on the bones, as it were, wholesome foods means vegetables, fruits, whole grains, beans, lentils, nuts, seeds with or without everything else. You want to eat fish? Eat fish. You want to eat seafood? Eat seafood. You want to eat some lean meat? Do. You want to eat eggs? Do. You want to eat dairy? Do. But the bulk of your diet should be vegetables, fruits, whole grains, beans, lentils, nuts and seeds. This is true all around the world where people do the best. It’s true in the Mediterranean where the diets are high fat but the fat is coming from nuts, seeds, olives, avocados, olive oil.

It’s true in the Far East where the diets are low fat because there’s lots of vegetables, grains, and less of the nuts and the avocado. And frankly it’s true of diets as diverse as vegan and paleo. People who really know what they’re doing with the paleo diet are eating a wide variety of plants, preferably wild plants, but not necessarily, and lean meat, preferably game. So it’s real food, not too much and it is mostly plants. And a vegan diet is a slightly wider variety of plant foods without the meat. But they’re actually more alike than different. So there really is incredible clarity about the fundamentals of healthy eating. And I think really the big issue for all of us is focusing our efforts on making the fundamentals of that dietary pattern more accessible in our culture and allowing for people to choose the variant on that theme that works best for them. So you need to eat well even in a world that keeps running on Dunkin. You need to eat well and feed your children well in a world that markets multicolored marshmallows as part of the complete breakfast. You need to be physically active in a world that gives you no time for exercise and gives you more and more technology to do everything that muscles used to do. So the theme of health eating unbelievably clear. The specific claims about my diet can beat your diet. All false. All somebody trying to sell you something. Step away from your credit card and nobody can get hurt.

Go ahead: Eat lean meat, eggs, and seafood, if that's what you want. Just remember, as nutritionist David L. Katz notes in video interview, the bulk of your diet should be vegetables, fruits, whole grains, beans, lentils, nuts, and seeds.

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The surprise reason sleep-deprivation kills lies in the gut

New research establishes an unexpected connection.

Image source: Vaccaro et al, 2020/Harvard Medical School
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  • A study provides further confirmation that a prolonged lack of sleep can result in early mortality.
  • Surprisingly, the direct cause seems to be a buildup of Reactive Oxygen Species in the gut produced by sleeplessness.
  • When the buildup is neutralized, a normal lifespan is restored.

We don't have to tell you what it feels like when you don't get enough sleep. A night or two of that can be miserable; long-term sleeplessness is out-and-out debilitating. Though we know from personal experience that we need sleep — our cognitive, metabolic, cardiovascular, and immune functioning depend on it — a lack of it does more than just make you feel like you want to die. It can actually kill you, according to study of rats published in 1989. But why?

A new study answers that question, and in an unexpected way. It appears that the sleeplessness/death connection has nothing to do with the brain or nervous system as many have assumed — it happens in your gut. Equally amazing, the study's authors were able to reverse the ill effects with antioxidants.

The study, from researchers at Harvard Medical School (HMS), is published in the journal Cell.

An unexpected culprit

The new research examines the mechanisms at play in sleep-deprived fruit flies and in mice — long-term sleep-deprivation experiments with humans are considered ethically iffy.

What the scientists found is that death from sleep deprivation is always preceded by a buildup of Reactive Oxygen Species (ROS) in the gut. These are not, as their name implies, living organisms. ROS are reactive molecules that are part of the immune system's response to invading microbes, and recent research suggests they're paradoxically key players in normal cell signal transduction and cell cycling as well. However, having an excess of ROS leads to oxidative stress, which is linked to "macromolecular damage and is implicated in various disease states such as atherosclerosis, diabetes, cancer, neurodegeneration, and aging." To prevent this, cellular defenses typically maintain a balance between ROS production and removal.

"We took an unbiased approach and searched throughout the body for indicators of damage from sleep deprivation," says senior study author Dragana Rogulja, admitting, "We were surprised to find it was the gut that plays a key role in causing death." The accumulation occurred in both sleep-deprived fruit flies and mice.

"Even more surprising," Rogulja recalls, "we found that premature death could be prevented. Each morning, we would all gather around to look at the flies, with disbelief to be honest. What we saw is that every time we could neutralize ROS in the gut, we could rescue the flies." Fruit flies given any of 11 antioxidant compounds — including melatonin, lipoic acid and NAD — that neutralize ROS buildups remained active and lived a normal length of time in spite of sleep deprivation. (The researchers note that these antioxidants did not extend the lifespans of non-sleep deprived control subjects.)

fly with thought bubble that says "What? I'm awake!"

Image source: Tomasz Klejdysz/Shutterstock/Big Think

The experiments

The study's tests were managed by co-first authors Alexandra Vaccaro and Yosef Kaplan Dor, both research fellows at HMS.

You may wonder how you compel a fruit fly to sleep, or for that matter, how you keep one awake. The researchers ascertained that fruit flies doze off in response to being shaken, and thus were the control subjects induced to snooze in their individual, warmed tubes. Each subject occupied its own 29 °C (84F) tube.

For their sleepless cohort, fruit flies were genetically manipulated to express a heat-sensitive protein in specific neurons. These neurons are known to suppress sleep, and did so — the fruit flies' activity levels, or lack thereof, were tracked using infrared beams.

Starting at Day 10 of sleep deprivation, fruit flies began dying, with all of them dead by Day 20. Control flies lived up to 40 days.

The scientists sought out markers that would indicate cell damage in their sleepless subjects. They saw no difference in brain tissue and elsewhere between the well-rested and sleep-deprived fruit flies, with the exception of one fruit fly.

However, in the guts of sleep-deprived fruit flies was a massive accumulation of ROS, which peaked around Day 10. Says Vaccaro, "We found that sleep-deprived flies were dying at the same pace, every time, and when we looked at markers of cell damage and death, the one tissue that really stood out was the gut." She adds, "I remember when we did the first experiment, you could immediately tell under the microscope that there was a striking difference. That almost never happens in lab research."

The experiments were repeated with mice who were gently kept awake for five days. Again, ROS built up over time in their small and large intestines but nowhere else.

As noted above, the administering of antioxidants alleviated the effect of the ROS buildup. In addition, flies that were modified to overproduce gut antioxidant enzymes were found to be immune to the damaging effects of sleep deprivation.

The research leaves some important questions unanswered. Says Kaplan Dor, "We still don't know why sleep loss causes ROS accumulation in the gut, and why this is lethal." He hypothesizes, "Sleep deprivation could directly affect the gut, but the trigger may also originate in the brain. Similarly, death could be due to damage in the gut or because high levels of ROS have systemic effects, or some combination of these."

The HMS researchers are now investigating the chemical pathways by which sleep-deprivation triggers the ROS buildup, and the means by which the ROS wreak cell havoc.

"We need to understand the biology of how sleep deprivation damages the body so that we can find ways to prevent this harm," says Rogulja.

Referring to the value of this study to humans, she notes,"So many of us are chronically sleep deprived. Even if we know staying up late every night is bad, we still do it. We believe we've identified a central issue that, when eliminated, allows for survival without sleep, at least in fruit flies."

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