#211 – AMA #36: Fruits & vegetables—everything you need to know

In this “Ask Me Anything” (AMA) episode, Peter discusses the nutritional profiles of various fruits and vegetables as a means of assessing their relative value. He explains the difference between eating them vs. drinking them, how processing fruits and vegetables can change their properties, and how one’s current state of health affects nutrition strategy when it comes to fruits and vegetable consumption. Additionally, Peter explains the potential benefits and negative effects of certain phytochemicals found in produce and concludes with a discussion of supplementing with green powders, multivitamins, and more.

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We discuss:

• The limitations of nutritional data and challenges of making broad recommendations [2:00];
• How one’s current state of health impacts their “optimal” diet [11:30];
• Defining “metabolic health” [14:45];
• The wide-ranging nutrition profiles of various fruits and vegetables [16:30];
• The benefits of fiber [20:45];
• Eating whole fruits vs. drinking fruit juice or smoothies [22:30];
• Drinking alcohol: metabolic effects, calories in alcohol, and more [28:30];
• Can excess fruit consumption lead to insulin resistance? [30:30];
• Glycemic impact of different fruits, using CGM data to assist decision making, and how fruit is fundamentally different from what we evolved to eat [31:30];
• Dietary approaches for people with a carbohydrate tolerance disorder (TD2, NAFLD, etc.), and when it makes sense to restrict fruit consumption [34:30];
• Nutrition profile of select vegetables: sugar content, micronutrients, and more [40:00];
• Phytochemicals in produce: potential positive health impacts on inflammation, cardiovascular (CV) risk, and cancer [44:30];
• Phytochemicals with potential negative health impacts [50:45];
• Nightshades and inflammation [53:15];
• How important is it to eat organic foods? [56:00];
• How necessary is it to wash fruits and vegetables? [1:00:45];
• How does food preparation change the nutritional composition? [1:03:45];
• Considerations when eating canned and frozen food, and paying attention to processed food additives [1:04:45];
• Supplementing vitamins and nutrients as an alternative to eating whole fruits and vegetables [1:06:15];
• Green powder supplements [1:11:15];
• Important takeaways [1:16:00]; and
• More.

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The limitations of nutritional data and challenges of making broad recommendations [2:00]

What we really know and don’t know:

• The following is true on average: People who eat more fruits and vegetables are healthier than people who don’t
• But if you really get into the details of this stuff, there’s far less that’s known than is represented as true
  • That’s a broader concept that applies to nutrition in general
  • And it speaks to why the nutrition chapter of Peter’s book has been “hands down posing the greatest difficulty”
  • And it’s not because Peter has nothing to say, it’s because there’s less to say definitively than he would’ve said 5 or 10 years ago
  • There are the obvious things:
    • Too much food is bad
    • Too little food is bad
    • Too little protein is bad
    • Certain micronutrients are essential
    • Certain things are toxic
    • After that, it starts to go from really clear, absolute knowledge to probable knowledge very quickly (And it does so quicker than it does with sleep, with exercise, and even with pharmaceuticals)

“And yet it’s the one area where I think people speak about things in more absolute terms than they do in anything else”

Why do people speak in absolute terms about nutrition despite the nuanced and complex reality?

• One explanation is that everyone on the planet has some “expertise” with nutrition because we eat food every single day
  • By contrast, not everybody exercises every day
  • But we’re conscious and we make deliberate choices when we eat every single day

“I think there’s also a very significant cultural and social component to this thing as well. So I think that’s where the tribalism comes from around nutrition.” —Peter Attia

On the flip side…

• It’s very difficult to acquire reliable knowledge in this space
• However, there are some really good scientists working on the mechanistic side of nutrition
  • Such as people who are really under very tightly controlled conditions, elucidating some of the most interesting knowledge with respect to energy balance, with respect to appetite, with respect to fuel partitioning, food reward
  • The problem is that it is nearly impossible to do this type of work in large sample sizes over long durations
  • And you need large sample sizes and long durations to infer hard outcomes that we care about, which are prevalence of disease or incidence of disease and ultimately mortality
  • So therefore to get insights on those topics, you have to rely almost without exception on epidemiology
• There are some reasonably well done, large clinical trials, but they require thousands of people and many, many years…And that means your interventions had better be very, very simple if you’re going to achieve compliance over that period of time.

All of this is to say…

• Nutrition is very hard and when we rely on epidemiology and we’re struggling to necessarily get it right in areas where the hazard ratios end up being quite small
  • when you get hazard ratios like 1.19, it’s very difficult to know that you’ve captured and removed all of the biases that fed into that

People doing good work

• Kevin Hall is really doing some super interesting work
• Peter says Kevin is one of the most thoughtful people on the subject of energy balance
  • This is an area where you can get answers to questions in months
  • And you don’t need thousands of people, you can actually do these in tens of people provided you’re using very precise instrumentation

Questions that can’t really be answer quickly

Example: Are omega 6 polyunsaturated fats inherently healthy or harmful? (a very vexing question)

• Peter has seen pretty compelling evidence that omega 6 polyunsaturated fats as substituted for saturated fats could actually be viewed as harmful
• For example, looking at the initially unpublished data from the Minnesota Coronary Experiment that completed in 1973, but didn’t get published in its first rendition until 1989 and then wasn’t reexamined and republished much later
  • If you look at those data, you could make a very compelling case that omega 6 polyunsaturated fats as substituted for saturated fats could actually be viewed as harmful
• But then you look at a whole bunch of other data and you might conclude that actually any harm associated with those fats is purely due to the confounders of what they track with, the seed oils that show up in low quality foods and junk foods
  • In other words, it’s not the seed oil that’s the problem, it’s the junk food that’s the problem
• This example just speaks to the type of questions that have profound importance but it’s unclear as to the answer

 

How one’s current state of health impacts their “optimal” diet [11:30]

• The goal of the podcast today isn’t for listeners to be told what they can and can’t eat
  • It is variable depending on your metabolic health diet, what you’re already eating
• The hope is for the listener to have a better understanding of the subject and to be able to apply that knowledge to their unique situation

Important point from Peter:

{end of show notes preview}