Pryme Vessyl x UCSF Collaboration


Pryme Vessyl Collaborates with UCSF to Help Cystinuria Patients Combat Rare Disease through Hydration

In wake of studies showing how increased fluid consumption can help prevent kidney stone recurrence, people with cystinuria are turning to Pryme Vessyl to help track their fluid consumption

SAN FRANCISCO Today, Mark One, the creator of the award-winning Pryme Vessyl, an intelligent cup that automatically tracks and displays your personal hydration needs, announced a strategic collaboration with the University of California, San Francisco Department of Urology to examine how Pryme Vessyl could be used to help people with cystinuria more easily track their fluid consumption. Ranked first nationwide in competitive funding for urology research – considered a reflection of the department’s caliber in this highly competitive federal funding arena – UCSF urologists are experts in cystinuria and the treatment of kidney stones.

Cystinuria is an inherited metabolic disorder that causes cystine to build up in the urine where it can lead to the formation of stones. These stones can get stuck in the kidneys, ureters or bladder. People with cystinuria tend to have recurrent stones and can have many, painful episodes every year. Some patients undergo thirty or more surgeries over the course of their lifetime to remove stones. As a result, there is a large focus placed on the prevention of stones, and hydration plays a pivotal role in this effort.

“Proper hydration is important for everyone, but it’s imperative for those suffering from cystinuria,” said Dr. Hanson Lenyoun, Head of Health for Mark One. “There’s extensive research showing that increased fluid consumption can help prevent kidney stone recurrence, but it can be difficult for people to track how much they are actually drinking. It’s even harder to collect and share that information with their doctor. We’re excited to collaborate with UCSF Urology to offer people a convenient way to automatically track their fluid consumption. We realize this type of patient-generated health data has the ability to enrich the doctor-patient exchange and help people optimize their care.”

Pryme Vessyl uses a proprietary algorithm paired with personal information to determine each user’s unique hydration needs at each point of the day. The device takes into account varying factors, including height, weight, age, biological sex, exercise and sleep habits, to determine the amount of water each individual needs throughout the day. The amount and timing of fluid consumed is tracked and logged so an individual can review and share the data as they see fit.

To learn more about Mark One and Pryme Vessyl visit:

Your Company Perks Are Killing You

by Dr. Hanson Lenyoun and Zachary Kazzaz


For the uninitiated, walking into tech companies’ office spaces can feel like stepping into Willy Wonka’s Chocolate Factory. Sweets and treats line the walls and stocked beverage fridges greet you at every turn. Employees are never more than a few steps away from a snack–and that’s before the free lunch appears.

These perks seem awesome, but there’s a side that isn’t discussed. While free snacks are meant to increase employee morale, few people acknowledge they may be harming employees’ health, well-being, and productivity, and negatively impacting the companies they work for. It’s time to take a step back and reconsider the costs and benefits of company perks.

From the Freshman 15 to the Tech 20

While set in a new venue with conference bicycles and Lego-filled innovation rooms, it’s important to realize the behaviors being perpetuated in these offices are not novel, and neither are the outcomes. We’ve seen this play out in the form of the “Freshman 15” – the weight gain of first year college students due to convenient access to fat and carbohydrate-rich foods, served buffet style. Now those former students are a bit older, their metabolisms slower, their lives significantly less active, and we’re setting them up for failure, again.

Colleges have realized the problem and are launching programs aimed at helping students build positive health and fitness habits. Yet in tech, we’re still on the wrong side of the curve, creating a hiring market where these Wonkian perks are expected, and we’re surprised when we end up driving young professionals to gain the more nefarious “Tech 20.”

Continue reading Your Company Perks Are Killing You

The Origin of 8 Cups per Day

8 Cups Lead

The origin of ‘8 cups’, and what it means for you today.

The truth is, there is no confirmed source of this “myth”, but there are a few potential candidates:

  1. In 1921 a scientist measured all the water he lost in one day (urine, sweat, etc.), which was 8 cups.
  2. In a 1945 report, the National Research Council wrote that 1 mL of water for each calorie of food consumed is a suitable allowance in most instances. For the standard 2,000 calorie American diet, this is about 8 cups.
  3. Renowned nutritionist Fredrick Stare said that the average adult should consume “6 to 8 glasses” of fluids per day in a book he authored in 1974. 

Regardless of where it comes from, with all the research and technological advancements since 1974, surely we can do better.

Ultimately, the 8 cups concept is flawed because it focuses on generalization rather than personalization. The goal was to make one recommendation that’s right for everyone, but that’s not possible. Each one of us is different, with different hydration needs that change constantly. One of our Mark One team member’s likes to point out the absurdity of suggesting that Taylor Swift and Shaquille O’Neal should both be drinking the same amount of water. To take it one step further, think about Shaq playing a game of pickup versus filming “Inside the NBA”, sitting in a studio – 2 very different days where the same person would require vastly different amounts of water to stay hydrated.8cups-wideEach person’s unique needs change moment by moment depending on who they are, where they are, what they’re doing, the time of day, and much more. Because of this extreme variability in individual water needs, it has been impossible to make personalized recommendations with any degree of accuracy… until now.

This is an exciting time! Our ability to measure the ever-changing factors that alter our hydration needs, like our activity level, location, consumption behavior, etc., enables us to take the guesswork out of how we are meeting our unique hydration needs. We now have the capacity to move beyond the static, one-size fits all hydration guidelines like “8 cups” that have been used up until now.

Pryme calculates each person’s unique needs using a variety of personal variables and then updates those needs over the course of the day in an intelligent manner. It’s a personalized, dynamic estimate of your unique hydration needs, so that you can hydrate intelligently and stay ready for your moments of greatness. We’ll talk more about Pryme in our upcoming posts.

– Dr. Hanson and Mark One


  1. Adolph EF. The regulation of the water content of the human organism. J Physiol. 1921 May 24;55(1-2):114-32.
  2. Food and Nutrition Board, National Academy of Sciences. Recommended Dietary Allowances, revised 1945. National Research Council, Reprint and Circular Series, No. 122, 1945 (Aug), p. 3–18.
  3. Stare FJ and McWilliams M. Nutrition for Good Health. Fullerton, CA: Plycon, 1974, p. 175.

Doctors: “Are diet sodas better for me?”

Diet sodas might be helpful on occasion, but are far from “healthy”

There are two sides to this debate: diet soda is either a great alternative or simply a wolf in sheep’s clothing. Truth is, our understanding of the short and long term effects of artificial sweeteners (the “diet” in diet sodas) continues to grow, and often times, findings conflict.

The rate of consumption for artificial and other non-nutritive sweeteners has grown tremendously over the past several decades. The early use of saccharin as an artificial sweetener was motivated by cost savings, a cheap sugar substitute.¹ Nowadays, non-nutritive sweeteners are used primarily for reducing calories and thus weight control.

Surprisingly, the efficacy of this strategy has not been definitively proven. Two recent studies support the idea that diet sodas can aid weight loss,² ³ while observational data shows that heavier individuals who drink diet soda actually consume more calories from food than those who drink regular soda.⁴

Another purported benefit of diet sodas is that they decrease the risk of diabetes. However, recent studies have shown that artificial sweeteners can alter the microbiome (bacteria) in the intestines that aid digestion and support the immune system. This alteration in our microbiome may increase our chance of getting diabetes just as much as soda, not only negating this purported health benefit,⁵ but also potentially causing harm.⁶

So, is diet soda healthy? Likely not, but it can be a better choice under some circumstances. I agree with the AHA and ADA; it’s best to use diet sodas either to transition off of sugary beverages or as an occasional treat.⁷ In the long run, if we play our cards right, our health will be better without them.

Yours in health,

Mark One Doctors

1 de la Pena, Carolyn. Empty Pleasures: the story of artificial sweeteners from saccharin to splenda. UNC Press, 2010.

2 Peters J et al. The effects of water and non-nutritive sweetened beverages on weight loss during a 12-week weight loss treatment program. Obesity June 2014, 22:6 1415-1421.

3 Ebbeling C et al. A randomized trial of sugar-sweetened beverages and adolescent body weight. NEJM Oct 2012 357:15 1407-1416.

4 Bleich SN, Wolfson JA, Vine S, Wang YC. Diet-beverage consumption and caloric intake among US adults, overall and by body weight. Am J Public Health. 2014 Mar;104(3):e72-8.

5 de Koning L, et al. Sugar-sweetened and artificially sweetened beverage consumption and risk of type 2 diabetes in men. American Journal of Clinical Nutrition. 2011;93:1321.

6 Suez J et al. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature. 2014 Sep 17. [Epub ahead of print]

7 Gardner C et al. Nonnutritive sweeteners: Current use and health perspectives. A scientific statement from the American Heart Association and the American Diabetes Association. Circulation. 2012;126:509. Link:

Doctors: “Are energy drinks bad for me?”

Think of an energy drink as a cup of coffee with around 7 cubes of sugar.

People tend to use these beverages as a source of alertness and focus. The “energy” that comes from energy drinks is typically from its caffeine. When it comes to the other ingredients, there isn’t much evidence to show a meaningful stimulant effect.¹

We’ve talked briefly about caffeine in a prior post, and it’s important to point out that the caffeine content can vary widely in different energy drinks, which can have adverse effects.² Also worth noting, energy drinks may be putting added strain on the heart.³ There has been a sharp rise in the number of Emergency Room visits related to consumption or over-consumption of energy drinks,⁴ perhaps related to caffeine toxicity.

The biggest day-to-day concern for me (with my patients) is that energy drinks typically come loaded with added sugar. Sugar-free varieties exist, but almost all of these contain non-caloric sweeteners that can irritate our stomachs.

Lastly, a societal concern about energy drinks is their tendency to be combined with alcohol. It has been observed that the desire to drink alcohol increases when alcohol is combined with energy drinks.⁵ ⁶

All in all, the answer to whether energy drinks make sense depends on how much and how often you drink them. Either way, it’s hard to make a case that these are superior to coffee or tea.

Yours in health,
Mark One Doctors

1 Bedi N, Dewan P, Gupta P. Energy Drinks: Potions of Illusion. Indian Peds. Vol 51; July 2014.

2 See

3 Doerner J, Kuetting D, Naehle CP, et al. Caffeine and Taurine Containing Energy Drink Improves Systolic Left-ventricular Contractility in Healthy Volunteers Assessed by Strain Analysis Using Cardiac Magnetic Resonance Tagging (CSPAMM). Radiological Society of North America (Conference Abstract). 2013 Dec.

4 See

5 McKetin R, Coen A. The effect of energy drinks on the urge to drink alcohol in young adults. Alcohol Clin Exp Res. 2014 Aug;38(8): 2279-85.

6 Peacock A, Bruno R, Martin FH, Carr A. The impact of alcohol and energy drink consumption on intoxication and risk-taking behavior. Alcohol Clin Exp Res. 2013 Jul;37(7):1234-42.