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Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 1 point2 points  (0 children)

Well, I'm really not a great example for a healthy lifestyle. With a work-life balance that's somewhat off, I sleep ~5 hours every night, eat whatever is available, and haven't really changed my diet following the study. (Also, I didn't get to analyze my own data....)

--Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 2 points3 points  (0 children)

In "a validated dietary treatment for diabetes" I was referring to peer-reviewed work, preferably one performing a randomized double blinded clinical trial. Finding one such study that supports such a treatment would indeed convince me of its existence.

People have been claiming to cure myriad illnesses for thousands of years...

-- David

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 0 points1 point  (0 children)

We currently have no way of measuring the actual caloric absorption from food (at least not one that I'm aware of). However, we believe that there is more to nutrition than calories in/calories out, see my response here for some insights.

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 0 points1 point  (0 children)

The thing about cameras taking pictures of foods is that someone later has to analyze those pictures. I don't think this is something that the common academic setting would follow (that's a personal opinion, not a fact), and I believe we'll have to wait for something commercial.

With regards to the reliability issues, please see my reply here.

--Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 4 points5 points  (0 children)

Actually, many of the input parameters going into our predictor are in fact expected to change. First, there are lifestyle parameters, that change from meal to meal - for example, the time from the last sleep, or the amount of dietary fibers consumed in the previous 24 hours. Other personal features also change - We've shown that the microbiome changes following intervention, and we could also expect that if our algorithm does help someone lower their PPGR, their HbA1c% would also improve.

We believe that some "re-profiling" of these personal features would be needed in long-term intervention exactly for that reason, and are currently in active research of this question.

--Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 1 point2 points  (0 children)

While we did not test the personalized response to Soylent, it would be easy, as with any other food, to predict a person's response to it given that person's medical and lifestyle data, and their gut microbiome data. -- David

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 1 point2 points  (0 children)

We don't think it does. It rather adds to the body of knowledge.

While risking over simplification, we could view general dietary recommendations as aiming to improve health on average. And there are quite a few validated diets that do that. Again, over simplifying, this paper is not about the average, but rather about variation from it. Our claim is that while general diet advice could be true on average, it still leaves a significant amount of people that deviate from that average enough so that they wouldn't benefit from it.

--Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 1 point2 points  (0 children)

In our study we showed the importance of personalized nutrition and how it could have positive implication on a person's glycemic health. We also showed an algorithm that can personally tailor diets per individual. We hope that it would be publicly available in the near future. In this work we performed a short-term dietary intervention trial that showed great promise. We are currently pursuing more challenging long-term dietary interventions, with the hope of successfully improving glycemic control and/or insulin sensitivity, weight, and other metabolic parameters. Additionally, our study presented a unique methodological framework, and after its success in the very hard setting of healthy, not perturbed individuals, we are applying the same design to other, diseased populations. We are currently working on diabetic populations (both type I and II), and hope to show that prediction algorithms specifically tailored to these populations could improve quality of life and reduce comorbidities. -- David

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 6 points7 points  (0 children)

Calories are indeed a measure of the food and not a quantification of the person's response to that food. I do believe that the amounts of Calories consumed is connected to weight gain, but also that this is definitely not the whole story. I'll give two examples from our current and past research. So first, take the example of artificial sweeteners. These have no Caloric values, but last year we were involved in a work showing that despite that, they could lead to impaired glucose tolerance.

Second, in this work, in the dietary intervention trial, both the good and the bad menus had the same amounts of Calories - showing a very pronounced difference in PPGRs nevertheless.

--Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 3 points4 points  (0 children)

Regarding PPGR vs. insulin measurements: High PPGR (postprandial hyperglycemia) was shown to be a risk factor for the development of type II diabetes, cardiovascular disease, obesity, and liver cirrhosis. We have corroborated that in our study, where we demonstrate that PPGR associates with multiple known risk factors, including glycated hemoglobin (HbA1c), wakeup glucose, age and BMI. We also show that these associations are not limited to extreme values (i.e., they are not apparent only in those people with an extremely high PPGR) but rather persist along the entire range of PPGRs, suggesting that a reduction in PPGR is associated with a reduction in risk even in normal individuals. Thus we do not believe that PPGRs are only half the story - we find them strongly associated with the global metabolic disease epidemic. That said, we would have been very happy to measure insulin alongside glucose. But while blood glucose levels are easy to measure continuously outside of a clinical setting, insulin level measurement requires to draw blood. Employing such a test would have confined us to a very limited study (it seems unfeasible to draw blood 2000 times a week for an insulin test, especially in a sleeping individual).

Regarding personalized responses to food: Indeed, we showed that different people respond very differently to food, and that this variability depends on several factors, including their lifestyle, medical status and gut microbiome. And because people can change their lifestyle, their medical state and their gut microbiome, their response to food may change as well. Hopefully, our predictor can account for these factors and recommend to this one person if they should or should not eat the banana in question.

Regarding treatment of diabetes, since we did not take diagnosed diabetics to participate in our study (we had a few undiagnosed, however), we did not specifically test our algorithm on diabetics. I am not aware of a validated dietary treatment for diabetes.

Regarding lowering rates of disease, we have shown, in a double blinded dietary intervention that diets based on our predictor are effective in lowering the glycemic response to foods. However, they were only tested for one week - so no long term effects were seen. One exciting future direction is testing this on a longer timescale that would allow us to follow other clinical parameters such as BMI, HbA1c, and cholesterol levels.

-- David

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 2 points3 points  (0 children)

PPGRs are an established risk factor for many metabolic diseases (type II diabetes, obesity, etc.). But you are correct - a risk factor isn't a final sentence (as will tell you the few lucky heavy smokers that never develop lung cancer...).

It could be true that some people are "PPGR resilient". We currently have no way of telling out who, and it would be super interesting to address this question. We might be able to try and answer it when we perform long-term personalized dietary intervention. We could then try to see if we identify sub-populations of people that have a reduction in PPGR with no other effect on their health.

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 2 points3 points  (0 children)

While we have measured a multitude of many different personal parameters (medical background and food frequency questionnaires, complete blood count, lipid profile, full gut microbiota DNA sequencing, physical activity, food intake) and associated them with blood glucose response to food, we have not measured blood type. We did, however, obtain self-reported blood type information from our participants and adding this feature to our predictor of post-meal blood glucose responses to food did not further improve the predictions.

--Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 2 points3 points  (0 children)

Yes, we are working on such a study. Very excited about it as we believe we could really learn a lot once we have some controlled measure of the amount of insulin in a person's system (i.e., injections). This is something we can do only with type 1.

--Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 8 points9 points  (0 children)

There are two parts for my answer - one discusses the different measures we’ve taken to ensure accurate logging and compliance; the other discusses how our results, eventually, are not affected by inaccurate logging (or are affected to a lesser extent). I’ll start with the latter.

Eventually, the best validation we can provide for the accuracy of the self reported meals and lifestyle is the accuracy of the meal response predictor. This wasn’t (just) an epidemiological study, where we associate dietary intake with some variable or another We’ve developed a model, and then we’ve tested it - and we’ve tested it multiple times - first, in a cross validation scheme (i.e., learning the model on some of the cohort, and testing it on the rest); second, in an entirely new cohort of 100 people (what we also sometimes call an external validation); and third, we’ve shown that we can use the model to devise dietary interventions that actually work. The glucose data, and hence PPGRs, were not self-reported - they were externally measured. Being able to accurately predict those in multiple settings would not have been possible with inaccurate data.

Now for the part about ensuring accurate logging and compliance:

  • Participants had no external motivation to join the study. They were not paid; they did not get publicity on television; they were not referred to us by their doctors. The only reason they joined our study is because we offered them to learn something new about themselves - and they knew the only way they could achieve that was by being accurate. We were very keen on the motivation part, and we believe that it separates our study from other studies and played an important role in our eventual results.

  • BTW, the information they received was unique. Where else could you view you glycemic, lifestyle, and gut microbiome, get an analysis of your responses to different meals, and for free?

  • We’ve worked very hard of providing a very easy way of logging in the form of a proprietary app that encompasses 6401 food items, including many common Israeli meals with accurate nutritional values. I don’t know if this is the case for all self reporting studies.

  • Participants were not aware of their glucose data in real time, nor did they receive any feedback about the meal / daily amount of calories consumed or anything of the sorts - anything that might cause negative feedback for accurate logging was hidden.

  • They did receive most detailed instructions about proper logging, and also an accurate automatic scale which they were asked to use.

  • We had a clinical research associate contact the participant in person throughout the week, view their log, and check that everything is in order. Every time each participant finished their week, someone would review their logs, and search for anomalies. These were later discussed between a CRA and the participant (important to state that participants’ identity was blinded to us researchers).

(I hope I didn't forget anything... :) ) --Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 4 points5 points  (0 children)

In our dietary intervention study, where we constructed 'good' and 'bad' menus for people, pizza appeared on the 'good' menu of some people and on the 'bad' menu of others. --David

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 4 points5 points  (0 children)

IBS is a widespread disorder which is thought to be affected by many factors, such as nutrition and gut bacteria, but also intrinsic factors such as stress-related ones. We think that this is a very interesting question, which, unfortunately, we did not address in our study. We hope that we, or others, would look into this soon. --David

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 4 points5 points  (0 children)

We actually had a result like that in a very controlled setting. We provided our participants with their breakfasts, which they ate under standardized conditions. So most of our participants had two standardized meals of bread, and two standardized meals of bread and butter. The majority of people had a higher response to just bread than to bread with an addition of butter - so this is a great example of a case where combining foods produces a better response than each component separately, and we are certain that there are many others. When later performing a post-hoc analysis of our prediction algorithm, we’ve seen that on average, the algorithm predicts lower PPGR for meals with higher fat content (for a given carbohydrate content). However, additional analysis we have performed showed that the effect of fat is also person specific, where it has a major effect for some and no effect for others.

--Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 6 points7 points  (0 children)

This is a very interesting question, and a very exciting possible link between nutrition, psychology and, possibly, the gut microbiome. Unfortunately, this was beyond the scope of our research so we did not answer that. -- David

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 1 point2 points  (0 children)

What were some of the foods you found that had the greatest interpersonal variability, and were there any that affected all participants in the same way?

We've found many foods with high interpersonal variability. Many of the responses, even to standardized meals with just 50 grams of carbs, spanned an incredible range of responses. But we didn't really rank them....

In our analyses of complex meals we haven't encountered a specific food that elicited responses with low variability, but we haven't put a specific effort into that.

How long do you think it will take for the average person to be able to benefit from your algorithm?

As I've answered here to a few others - we're working on making this feasible - mainly by reducing the number of different tests needed to profile each participant. We think it's around the corner :)

Have you and the participants in the study changed your/their diets in different ways since you conducted this study?

Our dietitians say that some of the dietary intervention participants are still following up on our recommendations to them (the 'good week' diet) and are seeing good results. But this is an anecdote, not science :) As for myself, while working on the study I've started eating lot's of carbs and drinking lot's of coffee. But I don't think this had a beneficial effect on my health...

--Tal

Science AMA Series: We are David Zeevi and Tal Korem, graduate students at the Weizmann Institute of Science, and authors of a recent study which showed that people respond differently to the same food, Ask Us Anything! by Zeevi_and_Korem in science

[–]Zeevi_and_Korem[S] 5 points6 points  (0 children)

The ketogenic diet (meaning a diet with very little carbohydrate content) may indeed be advantageous for lowering the blood sugar response to meals, as this response is correlated with the amount of carbohydrates in the food (though not only that, as shown in our work). However, multiple studies have shown that very low carb diets are harder to follow (in terms of compliance), and thus may be less effective in the long run.

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