Tag Archives: individualized nutrition

PREDICT 2 Study Experience: Reflecting on Recruitment

On June 10, 2019, I read a New York Times article that immediately drew my attention and inspired me to take the first step of my personal nutrition journey. Authors Cynthia Graber and Nicola Twilley were writing about a new nutrition company called ZOE and a series of studies ZOE was sponsoring to investigate individual responses to food, appropriately called “PREDICT.”

Graber and Twilley began by describing the growing interest in the DNA testing industry, as individuals continue to become increasingly invested in how their unique genetic information affects their health choices and physiological responses. They transitioned into talking about the impact of genetics versus lifestyle choices on diet-related health conditions like obesity. This is when the Tim Spector story came into play; the authors discussed his complex experience with twin studies and how that transformed into the studies we now know as PREDICT and the founding of ZOE. 

The article was published just hours after Tim Spector and his team presented the first findings from PREDICT 1 at the American Society for Nutrition’s annual conference. The authors briefly described the participant experience from PREDICT 1, and they mentioned that Tim Spector was actively recruiting for a second study in the U.S. If I wasn’t already enthralled at this point, I guarantee that after reading about PREDICT 2, I snapped to attention. 

I’ve participated in studies before (read more), but it was more about the cash and less about the personal interest (although the personal interest was definitely a factor in my motivation to complete the studies). Like I mentioned in past blogs, I was not paid for my participation in PREDICT 2. I was, however, given the opportunity to experience the scientific process in its rawest form, and to hopefully receive meaningful results afterward. Immediately after reading the New York Times article in its entirety, I filled out an initial screening questionnaire for PREDICT 2 online.

After submitting the questionnaire, I received an email from the PREDICT 2 team stating they would review my information and let me know if I qualified for the study. Two hours later, I got another email that said I was eligible to proceed with the recruitment process. I clicked a link to take an additional screening questionnaire, which described the details of the study process – what the researchers were looking for and how they planned to gather the right data. Four days after completing this questionnaire, an email from the study team let me know I was eligible to take part in the study. 

Thus began the Informed Consent process. I was instructed to read the Informed Consent form carefully, a document that explained what I would do as a study participant, described what the researchers would do with my data, and included many disclaimers about what I was agreeing to when I signed on to participate in the study. After reading the form, the next step was to schedule a call with a member of the study team. To ensure I took ample time to read and comprehend the content of the Informed Consent form, I couldn’t schedule the call for less than 24 hours after receiving the form (I thought this was interesting). I got the Informed Consent form on a Friday, and I scheduled my call for the following Wednesday.

On the phone call, the study team member told me more about the study, answered questions, and helped me schedule when I would begin the study. Originally I was going to begin the study at the end of July/beginning of August, but I ended up postponing until September as I would be traveling for work frequently in August. After the call, I signed the Informed Consent form. 

Later I got an email prompting me to download the study app and the data within the app needed for participating in the study. After that, all of my communication with the study team would be through the study app. A few days later, I got my study pack in the mail, and the rest is history.

Throughout the recruitment process, the study team emphasized in our correspondence the value of “contributing to ground-breaking science that can help improve our understanding of human biology for everyone.” They also, of course, add that if you complete the study successfully, you will eventually receive “non-clinical results” with information on how you uniquely respond physiologically to different types of food and how that can be applied to making positive, healthy lifestyle changes.

The organized and streamlined recruitment process I experienced before participating in the PREDICT 2 study gave me confidence going into the study that I was signing up for a legitimate experience. I found out about PREDICT 2 from reading the New York Times article, and according to one of the study team members who I chatted with on the study app, most participants found PREDICT 2 through the media, particularly the Gastropod podcast episode I mentioned a few days ago (link here). I’m glad I read that New York Times article, and I’m grateful for everything I learned during the study and the support I’ve received from ZOE.

My DNA Has a Story to Tell, So I Gave it a Pen and Paper

I just took a DNA test, turns out I’m a hundred percent that health nerd who’s definitely gonna blog about it… 

Thanks to a serendipitous sequence of events, I procured two DNA test kits right around the time I began the PREDICT 2 study in early September 2019. Genetic factors are an important piece of the personalized wellness puzzle. What will my DNA test say about me?

The test kits come from a company called Pathway Genomics, and the two DNA analyses I submitted were “PathwayFIT” and “CannabisDNA.” I’ll talk about CannabisDNA in another blog post, but PathwayFIT provides a personalized genetic report about what my DNA says about my unique diet, nutrition, and exercise needs and tendencies as well as addictive behaviors and weight-related health conditions. 

My plan is to compare the results of this PathwayFIT DNA test with the results of the PREDICT 2 study, which will provide a similar report based on my blood glucose and blood lipid responses to food as well as a microbiome analysis (at a later time). As a reminder, I did provide a DNA sample for the PREDICT 2 study, but at this time, DNA analysis is not part of the report I’ll receive from them. The comparison between PathwayFIT and PREDICT 2 will potentially be extremely insightful, but just to clarify, there are a lot of factors that affect the content of these types of health response reports, and we should keep this in mind while drawing insights from the comparison.

Pathway Genomics cites research estimating that genetics is responsible for 40 to 70 percent of an individual’s predisposition for obesity. Whether someone taking the PathwayFIT test is wanting to lose weight or maintain weight, Pathway Genomics claims that the information provided in the report may help someone “modify” their behavior. In the report, they recommend that an individual talk to their primary care doctor before making changes as a result of the content of the report.

The tests included mailing a simple cheek swab to a lab for analysis. It went like this:

  1. I registered the kit online, creating a profile on Pathway.com.
  2. There are two cheek swabs per test kit, so I filled out two labels and placed each one on a collection tube.
  3. I swabbed the inside of my right cheek for one tube and the inside of my left cheek for the second tube. The test instructions recommended swabbing with the “same force you use to brush your teeth.” I brushed up and down while rolling the swab for at least one minute per cheek/tube. After the minute was up, I was careful to insert the swab into the collection tube without touching any other surfaces to prevent contamination. 
  4. After that, I placed the tubes in the prepared bag for mailing, and I dropped it off in a post box later that day. 

I sent in my samples on September 6, and I received an email 5 days later confirming the receipt of the samples:

Once my results are ready, I will be able to log in to my account on Pathway.com and view my results on an interactive dashboard optimized for a computer, smart phone, and tablet. I couldn’t find any information on the website about how long it will take to receive a report with my results, but here is what I’m expecting to find out: 

  • Diet & Eating Behaviors
    • Diet Type
    • Satiety (feeling full)
    • Food desire
  • Nutrients
    • Vitamin A
    • Vitamin B2
    • Vitamin B6
  • Food reactions
    • Caffeine Metabolism
    • Response to polyunsaturated fats (omega-3 and omega-6 fatty acids)
    • Response to monounsaturated fats
  • Health predispositions
    • Obesity
    • Metabolism
    • Weight loss-regain
  • Exercise & fitness
    • Muscle power
    • Endurance training
    • HDL (good) cholesterol response to exercise
  • Diet Guidelines

Here’s a link to a sample report. It’s pretty conclusive so it’s a long report, but SUPER interesting for a health nerd like me. Pathway Genomics uses a “scientific strength” four-star rating system to express the “strength of the research evidence for the genetic marker and the associated result.” The more stars, the more confident one could feel about the volume of research supporting a given finding or claim. The less stars, the more cautious one should feel about a statement.

If you’re interested, there are different kinds of DNA collection kits you can order from Pathway Genomics (not promoting a product here, just an FYI):

  • PathwayFIT (this is the kit I submitted)
  • Sport iQ
  • Skin iQ
  • Nutrition iQ
  • FIT iQ
  • SkinFIT

Pathway Genomics heavily advertises their various accreditations:

  • College of American Pathologists (CAP)
  • U.S. Health and Human Services’ Clinical Laboratory Improvement Amendments (CLIA)
  • California Department of Public Health

And leading institutions that have provided input in the development of the test:

  • UC Berkeley
  • Harvard Medical School
  • Scripps Clinic
  • Pennington Biomedical Research Center
  • Salk Institute for Biological Studies
  • University of Copenhagen

I’ll be writing again once I receive my results and have time to analyze the report and make comparisons with the PREDICT 2 results. Stay tuned!

PREDICT 2 Study Experience: Day 7-10

This blog post is the eighth in a series on my participation in the PREDICT 2 study. Click the links below to read earlier parts of the series:

I’m writing to you from Day 11, which means I’ve finished the study and am officially free from my glucose monitor, activity tracker, and morning muffins! Today, I’m just mailing back the devices and scheduling my Quest Diagnostics appointment, so I’ll reflect briefly on the tail end of the study.

Day 7

I had another glucose drink to consume the morning of Day 7. I guzzled it down on my way to work and counted the minutes until I could eat again! I’m not sure how the glucose drink affects other people, but I was the most eager to eat lunch on the two days of the morning glucose drink.

Day 8

This was my last day of standardized breakfast!

Day 9 and 10

For the first time in over a week, I chose my own breakfast (and reported it in the study app). At this point, the study team let me know through the study app’s chat feature that I could experiment with different foods over the next two days to – hopefully – be able to see in my results how my body responded metabolically to this variety. 

Reflecting on the End of the Study

People tease me because I regularly like to reflect on things. But I think a reflection is particularly important here because participating in the PREDICT 2 study was such a valuable, insightful, and well-structured experience. The study process was impressively organized, and I felt fully supported by the study staff throughout my whole time as a participant. 

Food logging is a lot harder than most people realize, and the study team truly provided me all the tools needed to be as successful as possible. I wasn’t getting paid to complete the study – the only benefit I might receive would be my metabolic results – so I was passionate about following all of the “rules” as closely as possible. In my mind, the more accurately I logged my food or making sure to refrain from eating during fasting periods meant that I was maximizing the chance my results would be accurate and meaningful.

Now that the study is over, I don’t have much to do other than wait. I’ll continue to follow ZOE on social media and read more about initiatives in personalized medicine, but it will be awhile before I receive any feedback based on data analysis from my activity in the study. According to the study team, my results will be in the form of an app that is currently in development at ZOE. I can expect the results of my food responses within a few months and at least six months for my microbiome results.

The story doesn’t end here, though. I’m still waiting on the results from two DNA tests I did a couple weeks ago, and I have a microbiome test to submit as well! So while it may take some time before I have results to blog about, I do plan to keep the conversation going on PREDICT’s progress and the ZOE story, personalized nutrition, and the interplay between genetics and environment in the context of health. 

Predict 2’s Sponsor and Collaborators: ZOE, Tim Spector, and 25 Years of Science

This blog post is the seventh in a series on my participation in the PREDICT 2 study. Click the links below to read earlier parts of the series:


PREDICT 2 includes scientific collaborators from Stanford University, Massachusetts General Hospital, Harvard, Lund (Sweden), Oxford (UK), Tufts University, King’s College London, and ZOE. That last collaborator isn’t a person, it’s a new company founded by a scientist and two entrepreneurs. The three founders are together on the ultimate quest to investigate people, food, and nature versus nurture. 

ZOE is a new nutrition science company based in both Boston and London. The ZOE team has a “food is medicine” philosophy, reminiscent of the age-old Hippocrates quote:

“Let thy food be thy medicine and thy medicine be thy food.”

Meet the ZOE founders:

Tim Spector, PhD, Scientific Founder

Image credit: JoinZoe.com

Claims to fame: 

  • Professor of Genetic Epidemiology at King’s College London
  • Director of the TwinsUK study at King’s College London


  • Elected to Fellowship of the Academy of Medical Sciences
  • Previously the president of the International Society of Twin Studies
  • Directs the European Twin Registry Consortium (Discotwin)

Dr. Spector established the UK Twins Registry over two decades ago, in the early stages of his career. In 2019, the UK Twins Registry contains more than 13,000 twins between the ages of 16 and 98. It is the largest adult registry of twins in the UK, and its founding marks the beginning of what would be a long and successful career for Dr. Spector, closely investigating the relationship between genetic and environmental factors in the context of disease. His 25-year twin study of the thousands of twins from the registry took a deep dive into how genes, diet, lifestyle, and the microbiome – the same factors considered in the PREDICT studies – affect food metabolism.

Biographical information on Dr. Spector describes his collaboration with more than 120 research centers worldwide. He is in the top one percent of most-cited scientists, and he has published more than 800 research articles. He is also the author of two books:

  • “The Diet Myth,” published 2015
    • In this book, Dr. Spector discusses the role of both eating habits and the gut microbiome in affecting health outcomes and longevity. He encourages readers to eat more foods that improve gut microbiome diversity.
  • “Identically Different,” published 2013
    • In this book, Dr. Spector reviews how, along with the impact of genetics, how one’s environment and life experiences affect health outcomes.

Dr. Spector is known for criticizing low-fat and fad diets, instead recommending a high-fiber Mediterranean-style diet with lots of nuts and vegetables. Throughout his career, Dr. Spector had made incredible steps in uncovering genetic links to complex health conditions previously associated with aging and the environment. His various genome-wide association studies (GWAS) have resulted in the discovery of more than 500 novel gene loci in more than 50 disease areas.

Jonathan Wolf, Co-founder and CEO

Image credit: JoinZoe.com

Claims to fame:

  • Prior Chief Product Officer (2012-2016) for Criteo, a machine-learning company
  • Prior Senior Director at Yahoo! (2005-2008)

In 1997, Jonathan Wolf graduated from Oxford University with a degree in physics. By 2005, he would be managing corporate development in Europe as Senior Director for Yahoo!, and by 2009 he would be on his way to implementing the way machine-learning company Criteo now impacts personalized retargeting efforts across the globe. 

When Wolf started at Criteo in 2009 as Chief Buying Officer, he was in the company of just 30 enthusiastic start-up employees. When he left as Criteo’s Chief Product Officer in 2016, the company had more than two thousand employees, had gone public on NASDAQ, and had over one billion dollars in revenue. 

Criteo is provides “mass-market personalized retargeting” on the Internet. This is the kind of internet advertisement that gives you the “they’re watching me” vibe; when you leave one website that sells product X and see the same product X being advertised on a different website at a later time, companies like Criteo are responsible.

George Hadjigeorgiou, Co-founder and president

Image credit: JoinZoe.com

Claims to fame:

  • Prior CEO of HouseTrip
  • Co-founder of e-Food

George Hadjigeorgiou’s academic experience is rich with mechanical engineering. He has a bachelor’s degree from Tufts University and a master’s degree from Massachusetts Institute of Technology (MIT). He worked in various positions at Accenture for several years after his 1998 graduation from MIT, before ultimately landing at Yahoo! in 2004. 

Hadjigeorgiou co-founded the online food delivery company e-Food in 2011, and the company was bought by Delivery Hero in 2015. Delivery Hero services are available in more than 40 countries across the globe, including in Europe, Asia, Latin America, and the Middle East. Basically, Deliver Hero is the European version of “Door Dash” or Uber Eats.”

In 2012, Hadjigeorgiou began working for HouseTrip, which would later by acquired by TripAdvisor. He was CEO from 2014 to 2016 before joining the team at ZOE. Hadjigeorgiou is responsible for ZOE’s namesake; in Greek, “ZOE” means “life” (Hadjigeorgiou references the movie “My Big Fat Greek Wedding” in his Linked-in post about his endeavors at ZOE, which is very much appreciated).


What does machine learning have to do with ZOE and the PREDICT studies? According to a June 2019 press release from ZOE, the company is using machine learning techniques to evaluate all of the data procured during the PREDICT studies to ultimately produce a test and app for consumers to purchase and complete to learn about how their body uniquely metabolizes food. Essentially, my voluntary participation in the PREDICT 2 study, where there is no exchange of money between myself and ZOE, would be transformed into an experience that people would pay for. So with the help from myself, the thousands of other participants of past and future PREDICT studies, and all of our combined data, ZOE could make a serious business, making customers out of people interested in their personal physiological responses to food. And while ZOE grows its business, the scientific community will benefit greatly from new insights made possible only by the analysis of great volumes of data. 

PREDICT 2 Study Experience: Days 3-6

This blog post is the sixth in a series on my participation in the PREDICT 2 study. Click the links below to read earlier parts of the series:

I took Friday and Saturday off from blogging, so let’s rewind a bit to get caught up…

Day 3

I had a hard time getting enough blood out of my fingers for the first blood spot test before eating breakfast. Definitely one of the not-so-fun parts of the study. I tried to use the opposite side of my ring finger on my left hand, which I had also used for blood spot tests on Day 1. However, for the second blood spot test on Day 3, I decided to go with fresh fingers on my right hand, even though I had originally wanted to sacrifice only my left hand fingers for the sake of the fingers on my dominant hand. A writer’s typing fingers are her livelihood! Alas, for the second blood spot test I did use my right-hand ring finger. The trick this time? Soaking my hand in warm water – middle school prank style – for several minutes before the test. I also stood up the whole time and used a tall cabinet to hold the materials. Taking these steps made Day 3 blood spot test 2 the easiest and most successful yet.

The third blood test of the day was okay after I failed to fill the first circle (there are four). The directions say that if the first drop doesn’t fill the circle up to 80% you can squeeze out more drops up to 30 seconds after placing the first drop. I was worried that I was going to have to prick my finger twice to get enough blood for the rest of the circles, but I squeezed my finger like you would to get the last goo out of the toothpaste (for you squeamish folks out there, sorry about that) and was able to fill the rest of the circles.

For breakfast on Day 3, I ate the bluest muffins I’ve ever seen in my life. Surprisingly, they didn’t turn my teeth or lips blue (I was imagining the effect of a blue popsicle or cupcake). Like I mentioned in an earlier blog post, the blue muffins are part one of determining gut transit time. Read that blog post again for a refresher.

My standardized lunch of three normal-colored muffins was fine. They don’t taste bad! It’s just hard to eat muffins when everyone else in the employee kitchen area is microwaving super tasty-smelling food…

Day 4 

With Day 3 being my second and last day with standardized lunch and blood spot test, I began Day 4 happy to spend the rest of my study days only eating standardized breakfast. Of course, I still need to fast for three hours after the standardized breakfast, and I have to record all of my other drinks and meals in the study app. 

Day 5

I took a break from muffins on Day 5. Instead for breakfast I had the dreaded “glucose drink,” which has to be consumed in less than five minutes and must be consumed without my regular morning coffee (interestingly, because I drank coffee on Day 1 with the standardized breakfast, the study app prompted me to remember to log my coffee with breakfast every other day of the study). 

The Gastropod ladies from the podcast about PREDICT 1 described the glucose drink like “flat Sprite” that’s super sweet, and I completely agree with their description. There was probably six ounces of liquid and it was a struggle to swallow each sip. I had brunch with friends scheduled for 10:30am, and so to factor in the post-breakfast fasting time, I woke myself up at 7:30am on a Saturday to guzzle down this glucose drink, and it was no easy feat. 

Because my glucose response would spike so quickly due to the high amounts of glucose in this study day’s standardized breakfast, the study team requested that I remain as inactive as possible for my fasting hours following the glucose drink. I obliged by simply going back to sleep! 

Day 6

It was back to the muffin life on the morning of Day 6. However, my standardized breakfast also included milk and chocolate/vanilla protein powder shaken up in a shaker bottle. The drink tasted very similar to the chocolate milk I had on Days 1 and 3. 

Later in the morning on Day 6, I almost wrecked my post-muffin fast by eating a delicious looking glazed donut. I remembered my fast just in time; I took the donut home and ate it (also recording it in the study app) at the precise end of my morning fast. 

For the first time in the study, I recorded physical activity in the study app. If you remember, this is activity that can’t be tracked by the device I wear on my wrist at all times. This can be activity like weight lifting, cycling, or in my case – swimming! I took the plunge (there’s a water pun for ya) and took my first out of four swimming lessons on Day 6, and since the wrist activity tracker isn’t waterproof, it stayed in my locker for the duration of the lesson.

And now we’re caught up! Tomorrow I’ll start Day 7 with a second glucose drink, and then I’ll only be a few days away from finishing the study. I’ll continue taking notes over the next few study days, but I also have some more blog posts in the works, including a “Part 2” to “PREDICT: The Science.” Stay tuned! 

PREDICT: The Science

This blog post is the fifth in a series on my participation in the PREDICT 2 study. Click the links below to read earlier parts of the series:


Overview of the ZOE Scientific Project for Researchers & Clinicians
A ScienceKara Summary

I’m technically neither a researcher nor a clinician, but let’s see if we can crack the code, eh?

What is PREDICT 1?

PREDICT 1 was the first of – potentially – many PREDICT studies to come in the future. Specifically, it was a multiple test-meal challenge study that 1,100 participants completed over 14 days. Scientists analyzed the participants’ metabolic response to standardized meals. With this data, researchers can drive the development of an algorithm for predicting metabolic responses. So in theory, the data from the PREDICT studies, with thousands of participants could help PREDICT scientists provide predictive insight on metabolic responses for millions of people interested in improving their health through diet changes.

There are five biological markers PREDICT 1 scientists analyzed as a response to standardized meals:

  • Postprandial glucose (this marker most of all, at least for PREDICT 1)
  • Triglycerides
  • Insulin
  • Inflammatory markers
  • Self-reported hunger

Participants in the PREDICT 1 study were 1,100 healthy people mostly from King’s College in London, UK. 60% of these participants were made up of twins from the UK Twins Study, which is spearheaded by PREDICT scientist Tim Spector, PhD. A Harvard researcher team led a validation cohort at Massachusetts General Hospital, and ZOE researchers completed an additional three-week sub-study of 100 UK participants to investigate metabolic responses to different types of standardized meals.

Researchers finished gathering data in May 2019. PREDICT 2 launched in June 2019. This time, PREDICT would be a non-hospital-based study, but the two PREDICT studies’ sets of data would still be able to be “seamlessly combined.”

What is PREDICT’s end goal?

The ZOE report describes two doors that could be opened by the data and insights gained by the PREDICT studies.

  1. “Data-scaling” – releasing a product outside of a clinical study in 2020
    • Customers undergo similar protocol as the one I’m following as a PREDICT 2 
    • Customers consent to sharing data anonymously
    • ZOE can make money AND gather data
  2. “Traditional science”
    • Short- and long-term nutritional intervention studies to test the accuracy of any predictions made via experimental algorithms and (later) the efficacy of ZOE diets under controlled conditions
    • Additional PREDICT studies to continue to gather data, but in a lab setting; this door provides a chance to collect data unique to the lab setting versus at data collected at home (like what I’m doing with PREDICT 2)

The introduction to the report outlines five key hypotheses that provide a foundation for PREDICT. Here’s the gist.

  1. Variability: People respond to food in unique ways and it can be predictable.
  2. Postprandial: Scientists need to study how the body responds and changes after eating a meal (“postprandial”). Measuring “traditional fasting markers” is not enough.
  3. Predict: Nutritional responses are directly linked to health conditions, and nutritional responses can be measured. Thus, health conditions can be predicted and addressed.
  4. Algorithm: The more data scientists can analyze from individual participants in studies like PREDICT, the more accurate machine-learning will be to build predictive tests.
  5. Complex: Science needs hands-on studies like PREDICT – not just traditional observational studies – to obtain insight needed for true predictive algorithm technology.

What’s taking so long?

Why haven’t scientists figured out how to predict individual responses to food yet? The variability and complexity of the factors involved is overwhelming; ZOE scientists list “background exposures” like:

  • Time of day
  • Recent exercise
  • Previous meals 

It takes time, resources, and diligent volunteers to make a study like PREDICT function and produce useful results. We all have the same letters in our genetic code (AGTC); the words are just written in different ways. Millions of different ways.


I started to count the number of times the ZOE scientists used the term “postprandial” and lost count. Needless to say, “postprandial” would be blowing up a word cloud made up of the text in this report. The necessity for postprandial study expressed by the scientists in this report is what led to both PREDICT 1 and PREDICT 2. These types of studies are a huge undertaking, needing to standardize meals for participants and control factors like fasting time without the participant coming to a clinic every day. Plus, the participants in PREDICT 2 apply and activate their own glucose monitors and collect, package, and mail their own saliva, stool, and blood samples! Not to toot my own horn, but I’m really doing science a favor with my dedicated and studious participation in this study (wink)!

PREDICT 2 Study Experience: Day 2 Reflection

This post is the fourth of a series on my participation in the PREDICT 2 study. Click the links below to read earlier parts of the series:

Well, I made my first major blunder as a PREDICT 2 study participant: I forgot to put my activity tracker back on my wrist after taking a shower! I realized what I had done after arriving to work. With my commute being 45 minutes, I knew it wouldn’t be feasible to return home to retrieve the tracker. I went to the “Help” feature on the study app and tapped “Chat with us.” I sent a message explaining that I had forgotten to put the tracker on that morning, and I asked if it would be okay to remain as inactive as possible before returning home at the end of the work day.

The study team member who answers in the morning, Haya, thanked me for letting her know and that she would make a note of it. She said to resume normal activity, log any exercise in the study app, and to put the motion tracker back on when I got home. Crisis averted! 

Day 2: Return of the Muffins

I had my day 2 breakfast at 8:03am, consisting of three standardized muffins, looking and tasting the same as the muffins from day 1. I also had a cup of coffee, which I logged in the study app. 

It was just breakfast muffins today, so I was free to eat whatever I wanted for lunch and dinner. Today for lunch I had a chicken breast (~10oz) roasted with thyme, salt, and pepper and a simple ratatouille (1 cup) made up of eggplant, zucchini, and tomatoes seasoned with thyme, salt, pepper, garlic, and lemon. I had the same dish in the same servings last night, so I used the study app’s meal-copying function to add the same item as last night’s dinner. 

It’s definitely more difficult to log made-at-home meals than I anticipated. Obviously it would be easier to scan a barcode or look up an exact meal off of a restaurant menu. But in a normal week, I cook most nights, and I want my habits during the study days to be as close to my normal as possible so my results represent my usual responses to food.

I read an interesting article in the blog on joinzoe.com about the muffins used in PREDICT. While as a participant I am blind to the details, there are three different muffins I could be consuming:

  • High-carb, low-fat
  • Low-fat, high-carb
  • Average fat and carb

All of the muffins are plain vanilla flavored and the look basically the same except for the blue muffins I’ll eat tomorrow for breakfast. No, they aren’t blue because of any blueberry flavoring. It’s food dye, and it serves the purpose of helping the study team identify “GI Transit Time” (GI = gastrointestinal as in the GI tract or “gut”). Catching on yet? After eating the blue muffins, I’ll be able to let the study team know through the app when I “see them again,” and this data tells them how fast certain food components move through my digestive system and out of my body.

The PREDICT “Muffin Master is nutrition scientist Dr. Sarah Berry from King’s College London. Together with test baker Kate, Dr. Berry created the magical muffin recipe for PREDICT so the study team would have palatable standardized food with known amounts of food components like fat and carbohydrate. 

For the most part, the muffins remove natural variability found in foods because of something called the “whole food matrix.” This is useful for the study, as their aim is to identify how people uniquely respond to high-fat meals, high-carb meals, and anything in between. But how does this data translate to the “real world” where people don’t eat standardized science muffins? I’ll be interested in learning more about the answer to this question as I read more about PREDICT and the science behind the study’s methodology. While I doubt the answer is simply “Well ScienceKara, the data translates seamlessly, and there’s nothing to worry about,” I also think my own answer right now would be: Well ScienceKara, we have to start somewhere.

Read the ZOE blog about the muffins.

Listen to the Gastropod podcast episode where the two hosts talk about their experience in PREDICT 1. Hosts interview:

  • PREDICT study scientist, Professor of Genetic Epidemiology at King’s College London, director of the Twins UK study, and ZOE co-founder Tim Spector, PhD
  • Timothy Caulfield, BSc, LLM, LLB, a Canadian professor of law at the University of Alberta, the Research Director of its Health Law Institute, and current Canada Research Chair in Health Law and Policy. Caulfield provides an interesting opinion on the efforts to personalize nutrition. He makes the point that with this type of technology ZOE is building with data from PREDICT, populations that arguably need a lifestyle change to improve health and prevent disease the most are not likely to get involved (i.e. low socioeconomic status).

Stay tuned for more posts about the science behind the study tomorrow.

PREDICT 2 Study Experience: Day 1 Reflection

This post is the third of a series on my participation in the PREDICT 2 study. Click here to read the first post of the series. Click here to read the second post.

On day 1, I completed three blood spot tests (before breakfast, after breakfast, and after lunch) and ate two standardized meals with fasting in between. 

Blood spot test 1: 8:10am

Individual items included in a blood spot test kit.

A few minutes after 8:00 this morning, I prepared to do my first round of blood spot tests for the day. The PREDICT 2 study team had a video for me to watch as well as written instructions for completing the blood spot test (As my formal training was in technical writing, I definitely appreciate well-written instructions and organization. Also, I have to admit I have found three small typos in the study’s hard copy written materials – whoops.). 

The blood spot test was quick, easy, and mostly painless. I washed my hands thoroughly and rinsed my left hand with warm water for about 90 seconds. This is to improve blood flow to my fingertips. Standing up at my desk, I used a small tool included in the study packaging to prick my finger and push drops of blood onto four absorbent circles on the blood spot card. To register the completed test in the study app, I took a picture of the blood spot card, scanned the card’s barcode, and recorded the exact time I began pushing the first blood drop onto the card. 

Then, I slide the card into a protective sleeve and into an aluminum bag, which would eventually hold all three of my blood spot cards for the day. This aluminum bag contains a desiccant to dry out the blood samples, and I will keep it in the refrigerator until I mail the samples back to the study team on day 4.  

Day 1 breakfast: 8:21am

My breakfast for day 1 was two semi-sweet, dense muffins just a bit larger than golf balls and what looked like about one cup of chocolate milk (milk I received from the study pack mixed with brown chocolate powder, also from the study pack). I had to finish the meal in less than 15 minutes and record the exact time I began eating. After I had eaten a few bites of the muffin, I was able to have coffee or tea – plain – and I chose coffee. 

I haven’t had chocolate milk in years, and the drink did not taste bad! It wasn’t a lot of liquid, and paired with my regular morning coffee, it wasn’t a burden to finish at all. The muffins were not light and fluffy like some muffins can be, but they were also not bad-tasting. I may not go to the store and pay for the very same muffins, but for study food, I feel like I can’t complain. 

After completing the breakfast, I logged all of the food by scanning the packaging and manually recording the coffee I drank. Then, I sat down at my desk, set a timer for two hours, and fasted until my next blood spot test. 

Day 1 lunch: 12:21pm

After doing my mid-morning blood spot test (10:21am), I fasted for another 2 hours and had breakfast a little after noon. Lunch was three muffins that tasted and looked identical to the breakfast muffins. No chocolate milk for lunch, though – just a glass of water (still, not sparkling) and eight fluid ounces of coffee (which I logged in the app). 

To my surprise, I was satiated after my breakfast and was only just starting to feel hungry when lunchtime came around. I’ll be interested to see how I feel as I fast over the next two hours before my last blood spot test of the day.

Day 1 Reflections

Throughout the day, I received notifications from the study app asking me to rank my hunger and alertness by moving a marker along a line, with the left being not hungry or not alert at all and the right being very hungry or very alert. Like I mentioned, I expected to be more hungry following my breakfast and lunch meals, but I felt full from the lunch for most of the afternoon. It wasn’t until about 5:00pm or so that I started wanting my next meal. For perspective, on a normal day, depending on what I eat for breakfast and lunch, sometimes I’m hungry as early as 3:00pm. If I’m hungry in the afternoon I’m much more likely to have a snack when I get home from work, and most often that snack is something unhealthy like chips or another processed food.

Answering the alertness question was more difficult. I had trouble falling asleep last night and thus woke up this morning feeling less rested than I normally would be after a good night’s rest. I’m not sure if the meals I was given were supposed to make me more or less alert, but I’m hoping that my low-quality sleep won’t affect my results from day 1. 

Overall, I think day 1 went pretty well. The meals were tolerable taste-wise and I haven’t felt overly hungry or uncomfortable in between. My biggest complaint is probably of the blood spot tests. My first test went fine; I filled each circle with blood easily. For both the post-breakfast and post-lunch tests though, I had to use a second, spare finger prick device each time to create a second cut on my finger to produce enough blood to fill the four squares. I’m unsure about why my blood flow was so poor for the second two tests, but I’ve got adhesive bandages on my left middle and index fingers, I can type just fine, and all will heal quickly! There is one day in between the two finger spot test days (a purposeful choice by the study team?), so I’ll be ready to do more blood spot tests when day 3 rolls around.

Tomorrow I will be posting a day 2 reflection, but in the days after, I won’t do a study reflection every day as many of the days will be the same after day 3. I’ll continue to post every day about the series, though, including a discussion of the science behind PREDICT 1, PREDICT’s sponsors and collaborators, a reflection on PREDICT 2’s recruitment process, and some other DNA and microbiome tests I’m doing in comparison to / reflection upon my experience with the PREDICT 2 study.

PREDICT 2 Study Experience: Set-up Day + The Study Pack

This post is the second of a series on my participation in the PREDICT 2 study. Click here to read the first post of the series.

Today was set-up day. I started off with a coworker (and friend, @Meghan) helping me install the glucose monitor on my left (non-dominant) arm. It takes 16 hours or so to calibrate, and I’ll keep it on for the duration of the study. Later I also “activated” my activity tracker (“activate” being I took it out of the package and put it on my left wrist like a watch).

Later in the morning I did potentially the strangest thing I’ll ever do at work. I’ll spare you the details; I’ll just say that the stool sample had to be collected during the set-up day so I did what had to be done. 

Before lunch I gave my saliva sample, which was quite literally spitting into a tube. I carried all of my samples home, and I’ll mail them back later this week. I had a call with a nutritionist from the study on my way home from work, and she confirmed that I had done all of my to-do items for the day. She talked me through the first couple of days of the study, asked if I had any questions, and let me know that if I ever needed anything, someone from the study would be able to chat with me through the app. That’s definitely a benefit to having collaborators from both the U.S. and the U.K. – different time zones so someone is always available for the study participants.

For tomorrow, “day 1,” I’ve got my standardized breakfast defrosting in the refrigerator and my standardized lunch ready to go. It looks like it’s muffins and chocolate shakes for me tomorrow! Of course, I can eat whatever I want for dinner, and I’ll just need to do some careful logging of the ingredients and serving sizes so the study team knows what nutrients I’m consuming. 

Standardized meals for day 1 of the study. I’ll scan the barcodes with the app to log each meal.

The study pack

I received my study pack in the mail on the Friday afternoon before I would begin the set-up day on a Monday. The box had several smaller boxes inside with labels and storage instructions. There was a long, thin box labeled “muffins” that I stored in the freezer, and I put a smaller box of other shelf-stable food items in the refrigerator. Non-food items included:

  • Food scale for weighing food ingredients for my meals that are not standardized by the study team
  • Cup and shaker for preparing shakes
  • Photo card for taking pictures of all the non-standardized meals that I eat
  • Study guide with information about the study
  • Tape measure for doing body measurements
  • Wearable activity tracker
  • Glucose monitor, reader, and adhesive patches
  • Return boxes for samples and devices
  • Sample collection kits for at-home collection and in-lab collection

My experience so far has been that the study team is extremely organized and prepared. In a white paper prepared by the ZOE team (“Overview of The ZOE Scientific Project for Researchers & Clinicians”) in June 2019, the authors mentioned that the PREDICT 2 study includes upgrades from PREDICT 1 that “improve data collection” and “reduce participant burden.” I’m pondering if those upgrades include the study pack experience because everything is extremely organized, and I can see how an unorganized box would be particularly disconcerting for the study participant, especially at the beginning of the study. 

That’s all I have for today, the set-up day. Tomorrow I’ll be posting a day 1 reflection as well as discussing the study that started it all: PREDICT 1.

Forging the Future of Personalized Nutrition: My Experience, My Contribution

Introducing the PREDICT 2 Study

I am less than 48 hours away. 48 hours away from beginning my participation in a study that will potentially provide insight into how my body metabolizes food. Not how people my age/gender/race tend to metabolize food, but how my body uniquely metabolizes food.

This study is riding the wave of personalized nutrition that’s been surging through the scientific community for the last decade. Because as scientists learn more and more about nutrition and the digestive system, the clearer it becomes that metabolism is a deeply personal experience.

Imagine this. Instead of following the latest popular diet (i.e. gluten-free, paleo, keto, intermittent fasting), people have the opportunity to take a test to identify their unique responses to different foods. For example, a gluten-free diet may work for some (Celiac disease, gluten intolerance), while for others there might be something else in wheat products that’s causing them discomfort. In theory, this test could identify what “something else” is. 


The study is called PREDICT 2, and it involves following a schedule of eating pre-prepared meals and providing blood, saliva, and stool samples for analysis. “PREDICT” stands for “Personalized Responses to Dietary Composition Trial,” and I’ll talk more about the study, its sponsor (a commercial company, Zoe Global Limited), and the collaborators involved (Stanford University, Massachusetts General Hospital, King’s College London, and Tufts University) in more detail later this week. I’ll also be blogging about PREDICT 1, a two-week study that measured physiological responses to specific foods. Researchers showcased preliminary results from PREDICT 1 at the American Society of Nutrition conference early in summer 2019.

12 Days

The study will take place over 12 days: one set-up day, 10 study days, and one follow-up visit to a clinic where I’ll have blood samples taken. I received my study pack in the mail two days ago, and it contained all of the items I’ll need throughout the study, including the standardized meals. 

On some days, I’ll have standardized breakfast and lunch meals that I’ll eat. Depending on the day and the samples I need to provide, I’ll need to wait 2-4 hours after each standardized meal before eating again. I can drink water, coffee, and tea during these times, but they recommend that I drink about the same amount of caffeine that I normally do every day.

I’ll log all of my non-standardized eating and drinking activity in a mobile app I downloaded on my phone. If you’ve ever used My Fitness Pal to track calories and nutrients you’ve consumed through food, the app as very similar to that.


On the set-up day, I’ll use materials I received in the study pack to collect a stool sample. This sample allows scientists to analyze the diversity of my microbiome, which is key to understanding my body’s unique response to certain nutrients in food. I’ll also collect a saliva sample on the set-up day, which provides the study team with samples of my DNA. The study team describes that DNA samples enable them to “identify certain genetic characteristics that have been previously associated with [my] responses to foods that [they] will measure during the study.” 

On some days, I’ll provide blood samples at specific times before and after meals. From these samples, study scientists can learn about how my blood fat levels change throughout the day and before and after specific meals. The study team describes blood fat levels as a “key metabolic indicator and one of the two main sources of energy in your body,” with blood sugar, or blood glucose, being the other main source of energy.

To measure blood glucose, I’ll be wearing a blood glucose monitor* throughout the study. I activate the monitor myself on the set-up day, about 16 hours before the first study day. The monitor takes this time to calibrate.

*This glucose monitor is FDA-approved for use in the management of diabetes but not for evaluating blood sugar levels in non-diabetic contexts, including this study

In addition to the glucose monitor, I will also be wearing an activity tracker on my nondominant wrist throughout the study to measure my physical activity and sleep levels. This tracker is very similar to FitBit technology.

After the 10 study days, I will visit a Quest Diagnostics Patient Service Center to provide a blood sample. The study team requires that I do this within one week of the tenth study day and before 11:00am so the samples can be shipped and processed at a central lab the following day. 

All of the sample analysis relies on knowing exactly what I consumed to elicit certain physiological responses. Thus, it’s crucial that I follow the food and drink schedule as closely as possible, eating and drinking standardized meals and drinks when scheduled and carefully recording my food and drink consumption at all other times.


I am not getting paid to do this study, but I am pretty pumped about getting my results back. The study team is hoping for 1,000 participants, so potentially you could be involved too! A few months after the study, I will be contacted by the study team to discuss my results. If I want them to, they can also share the results with my primary care physician. Essentially, I’m hoping for information on my personal physiological response to components of different foods and how those responses compare to common responses to food. 

While the insights gleaned from this study will likely help build an algorithm for predicting individual responses to food, the informed consent form states: “the predictive value of this research is not yet proven and it is unknown whether you will benefit from the information”

Over the next couple of days, I’ll be posting regular updates about the study as well as providing background information about the people and science involved. I’m really excited (as nerdy as it sounds) to participate in a study that’s doing awesome things for science by learning how different people respond to different foods and what factors account for those differences. I hope people will ask questions about my experiences and be inspired to participate in meaningful studies like this in the future!

Note: While the PREDICT 2 study team encourages participants to share information about the study, the statements made in this blog post and future blog posts are based on my own research and sets of opinions. 

This blog post is the first in a series on my participation in the PREDICT 2 study. Click the links below to read earlier parts of the series: