This was another fun episode to record mostly because I got to answer not one but TWO questions from listeners and I got to spend not one but TWO segments discussing the answers to those questions with my dear friend and sometime foil, Juliet. If you didn’t hear the show, this synopsis will bring you a flavor of what you missed. If you did, then this is a little bonus with lots of additional little tidbits.

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Table of Contents

• Blood Type Diet

• Jeff and Juliet Discuss Their Coaching Philosophie …

• Episode takeaways:

  • References used for the MMB

Blood Type Diet

I heard about this from a listener who reached out after he cam across it on another podcast. The guest on that show was Dr. Scott Vrzal, a chiropractor with a book and app to sell who spouted a lot of, shall we say, interesting ideas about how your blood type dictates what you should eat and how you should behave and woe is you if you aren’t doing things correctly! Have you heard of this?/ I certainly had not. On this episode we looked into it and unsurprisingly found out that it is, like so many other things that come from the alternative health gurus like Vrzal, not based on much. Forget what you may have heard about the blood type diet—it's basically a glorified diet fad with about as much scientific credibility as my cat's opinion on quantum physics. We dive into the absurdities of this diet in our first segment, calling out the claims that your blood type should dictate your food choices and athletic pursuits. Spoiler alert: it's all nonsense

Jeff and Juliet Discuss Their Coaching Philosophies

About Juliet according to Juliet: Juliet comes to triathlon coaching after a rich and varied path both as an athlete and a professional. The beneficiary of a multi-sport childhood in New England, Juliet focused on rowing at Harvard, becoming the youngest member of the 1988 Olympic team. A keen observer of her collegiate coaches’ approach to building a nationally ranked rowing powerhouse, Juliet noted the emphasis on community, leadership, teamwork and meeting each athlete where they are. After college Juliet started a nonprofit in South Africa’s black townships; ran teaching programs across southern Africa; went to business school at Stanford; worked with refugees on the North Korean-Chinese border; raised two sons and two dogs; enjoyed stints at Nike, Mercy Corps and Friends of the Children; moved her family 5 times across 24 times zones to support her husband’s career; served on school and non-profit boards; coached four different youth sports; learned Dutch; hosted a blog; and built a career as a project manager.

In 2014, Juliet returned to competitive sports, first as a tennis player and then as a triathlete. She quickly remembered how much she loved racing and competing, both as an athlete and as a mentor and coach. In 2017, Juliet started working with LifeSport Coach and Founder, Lance Watson. Later that year, she started the BATWomen, a high-performance women’s triathlon team, in Oregon. Excited to take it one step further, Juliet earned her USAT and Ironman Coaching Certifications, started coaching while working with LifeSport as a partner on new business development and operations. Juliet coaches triathletes, runners and cyclists of all backgrounds and delights in the process of helping them reach their goals. 

In the second half of the show, we moved into the world of triathlon coaching with none other than Juliet Hochman. We chatted about our personal coaching philosophies and how we adapt our strategies to meet athletes wherever they are on their journey. Whether you’re a seasoned competitor or just trying to make it across the pool, we’ve got tips that will resonate with you. We’ll share our experiences, the highs and lows of coaching, and how sometimes believing in your athlete can lead to some pretty remarkable breakthroughs. Spoiler: there’s a lot of vulnerability and laughter along the way, because let’s be honest, if we can’t laugh at ourselves while we’re sweating it out, what’s the point?

We didn’t get to touch on all of the topics that we had on our list to discuss but we did manage to cover:

• Basic coaching philosophy

• Swim

• Bike

• Run

We still had other things to share so if you are interested in knowing more, let us know and we would be happy to do a followup segment to include things like transition, nutrition, recovery, race plans and more.

Episode takeaways:

• The blood type diet is a complete myth with no scientific backing, so don't waste your time on it.

• Triathlon coaching is all about meeting athletes where they are, emotionally and physically, and pushing them to their potential.

• If you want marginal gains in triathlon, focus on sleep, strength training, and a well-structured plan rather than gimmicky diets.

• Coaches need to balance being cheerleaders and taskmasters, adjusting their approach based on the athlete's needs at any given time.

• In running, learning to hold your pace while fatigued is key, and progression runs are an essential tool for that.

References used for the MMB

Blood Type Diet: A Comprehensive Guide

By Stephanie Watson, Amy Gopal, Nichole Schmidt, Stephanie Booth

Medically Reviewed by Kathleen Zelman, RD, LD, MPH

https://www.webmd.com/diet/blood-type-diet 

Key Points

• The idea of the blood type diet was introduced in 1996, by a naturopathic doctor named Peter J. D’Adamo.

  • Claimed that certain foods can lower inflammation, boost energy, help with weight loss, and prevent disease

  • Article notes that the explanation of how this idea works is based on descriptions written by the creator and not backed by WebMD

    • Antigens react chemically with food 

    • Different gut bacteria depending on blood types 

    • Type O: first humans (hunter-gatherers) who ate fewer carbs and more protein had type O blood → high protein diet suggested

    • Type A: descended from farmers → vegetarian diet is urged

    • Type B: evolved from nomadic tribes whose diet were rich in meat and dairy→ can digest more fat; mixed diet with meat, fruits, dairy, seafood, and grain suggested

    • Type AB: have low stomach acid → avoid caffeine, alcohol, and smoked or cured meats

  • The blood type diet also suggests exercise based on one’s blood types

    • Blood Type A: yoga and tai chi

    • Type O: vigorous aerobic exercises (ie. jogging, biking) for up to an hour per day

    • Type B: group exercises (ie. tennis, martial arts, or golf) 

    • Type AB: mix calming and aerobic exercises 

• This article notes that “[i]n the years since D’Adamo introduced the Blood Type Diet, many studies have looked into whether the diet works, but none of them have shown a clear link between eating according to your blood type and better health.”

  • Cusack et al. (2013) study of existing medical literature on the subject (1,415 references in total) showed that no studies had evidence to support the idea that the Blood Type Diet works. 

  • A 2021 study examining the benefit of a plant-based diet on heart disease based on blood type showed no connection between blood types and health outcomes.

• According to the medical reviewer of this article, Kathleen Zelman, while “[the blood type diet is] somewhat of a gimmicky way to try to get people to eat healthier…[and t]here is absolutely no science to substantiate that your blood type dictates the kind of diet that you should be on”, elements of the Blood Type Diet work since it is mostly a healthy, plant-forward diet as shown in a 2014 study that found adults eating the type A diet showed improved health markers regardless of their blood type.

• The blood type diet is not necessarily “customized” for the consumer since it fails to take into account other health conditions that may benefit from certain dietary choices not suggested by the blood type diet.

• While the article notes that the food choices suggested by this idea are not concerning, there is an issue with some items that people are told to stop eating, which contain good nutrients, such as eggplants, beans, and whole grains

• The best type of diet is one customized for your needs and health conditions

• The general idea of the blood type diet is to eat less processed foods as well as added sugars and to eat lots of lean meat, fruits, and vegetables, which are beneficial to our overall health. However, strictly following the blood type diet with one’s family could be challenging when individuals are trying to meet different nutritional needs. 

Harvard Health Publishing: Diet not working? Maybe its not your type

By Robert H Shmerling, MD (2022)

https://www.health.harvard.edu/blog/diet-not-working-maybe-its-not-your-type-2017051211678 

Key Points:

• According to D’Adamo, choices in diet, condiments, spices, and exercise should depend on one’s blood type

• This theory is tied to our ability to digest certain foods depending on the lifestyles of our ancestors 

  • O: earliest humans were hunter-gathers with high protein diet

  • A: evolved when humans began farming and had more of a vegetarian diet

  • B: evolved among nomadic tribes with high dairy consumption

  • AB: evolved from intermingling of A and B type populations

• No evidence to prove its effectiveness or ineffectiveness

The Blood-Type Diet: An Evidence-Based Review

By SJoeLeech, MS (December 2023 on Healthline)

Medically Reviewed by Megan Soliman, MD

https://www.healthline.com/nutrition/the-blood-type-diet-review 

Key Points

• The central theories of this diet has to do with the idea that the wrong type of lectins could cause red blood cells to clump together and increase risk of disease for certain blood types

  • This article notes that while a 2004 review on the history of lectins suggests that raw lima beans may affect red blood cells in type A people, majority of lectins interact with all ABO blood types indicating that lectin in diet may not be blood type specific

• According to Tsamesidis et al. (2022), association between blood types and diseases, such as hepatitis, thrombosis, cardiovascular diseases, cognitive disorders, etc. have been made. However, no studies show that these associations are related to diet.

• While certain foods are associated with better health markers, so research supports the claim that specific diets are better for each blood type

• Diet plans work differently on each person, so working with a healthcare professional and nutritionist to develop a customized nutrition plan is important

• Diet recommended by D’Adamo:

ABO genotype, 'blood-type' diet and cardiometabolic risk factors

Wang et al. 2014

https://pmc.ncbi.nlm.nih.gov/articles/PMC3893150/ 

Key Points

• This study used diet questionnaire data and biomarker data to assess the association between Blood Types and Cardiometabolic health when subjects consumed a diet adhering to certain Blood Type Diets.

• Study revealed that adherence to the A, AB, and O Blood Type Diet was associated with favorable benefits in certain cardiometabolic risk factors.

• However, the findings did not support the hypothesis of the Blood Type Diet since the effects of the diets observed in the study were independent of the individual blood groups of the participants. 

• This study reports similar points shared in the WebMD article from above:

  • Previous evolutionary studies conducted by Saitou & Yamamoto (1997) as well as Calafell et el. (2008) involve phylogenetic analysis of human ABO alleles that suggest that Blood Type A is the ancestral human blood group opposed to Blood Group O postulated by D’Adamo, questioning the validity of the Blood Type Diet.

Introduction: Building off of the idea of the Blood Type Diet introduced by P.J. D’Adamo in his New York Times bestseller book “Eat Right For Your Type”, this study aimed to assess the association between Blood Types and Cardiometabolic health using biomarkers when subjects consumed a diet adhering to certain Blood Type Diets.

Methods: Dietary intake of participants (n=1455; age 20-29; 993 women and 462 men; 703 white, 491 east asians, 155 south asians, 106 others) of the Toronto Nutrigenomics and Health study, recruited between October 2004 and December 2010, were assessed using a one-month, Toronto-modified Willet 196-item food frequency questionnaire to calculate a diet score that determined the participants’ relative adherence to the four Blood Type Diets. Blood group of participants determined by genotyping two SNPs in the ABO gene. Cardiometabolic biomarkers were assessed across tertiles of each Blood Type Diet score taking into account age, sex, ethnicity, and energy intake of the participants as covariates. Homeostasis model of insulin resistance (HOMA-IR) calculated as follows: (insulin*glucose)/22.5. Homeostasis model of beta-cell function (HOMA-Beta) calculated as follows: (20*insulin)/(glucose-3.5).

Results: Adherence to the Blood Type A Diet was significantly associated with lower BMI, waist circumference, blood pressure, serum cholesterol, triglycerides, insulin, HOMA-IR and HOMA-Beta (p<0.05). Adherence to the Blood Type AB Diet was significantly associated with lower levels in blood pressure, serum cholesterol, triglycerides, insulin, HOMA-IR and HOMA-Beta (p<0.05). Adherence to the Blood Type O Diet was significantly associated with lower triglycerides (p<0.0001). No significant associations found for the Blood Type B Diet. However, the effect observed by the different blood type diets corresponded to the study population as a whole and was independent of the individual blood groups.Nothing to do with what blood type you are, just makes a difference what you eat

A Brief History of Human Blood Groups

Farhud and Yeganeh (2013)

https://pmc.ncbi.nlm.nih.gov/articles/PMC3595629/

Key Points:

• At least 3 hypotheses exist about the emergence and mutations of human blood groups

  • Hypothesis #1:

    • Primary Races Hypothesis: Blood group A emerged in Europe, B in Asian, and O in South America, all of which gradually migrated and mixed 

  • Hypothesis #2:

    • The emergence of A and B blood groups resulted from mutations of the O group

    • O blood make up 75-100% of old races (Red Indians of South America and Eskimos)

    • A & B are dominant in most recent ethnic groups

• Hypothesis #3: 

  • O group emerged from A & B groups that resulted from mutations to the original AB group

• Blood type is determined by the glycoproteins (antigens) found on a person’s blood cells, which are determined by the alleles inherited from one’s parents

  • The gene located on chromosome 9, known as the ABO glycosyltransferase determines ABO blood type

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