Watermelon Juice | L-citrulline

Figueroa A, Wong A, Jaime SJ, Gonzales JU. Influence of L-citrulline and watermelon supplementation on vascular function and exercise performance. Curr Opin Clin Nutr Metab Care. 2017 Jan;20(1):92-98. doi: 10.1097/MCO.0000000000000340. PMID: 27749691.

Bailey SJ, Blackwell JR, Lord T, Vanhatalo A, Winyard PG, Jones AM. l-Citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans. J Appl Physiol (1985). 2015 Aug 15;119(4):385-95. doi: 10.1152/japplphysiol.00192.2014. Epub 2015 May 28. PMID: 26023227.

Fueling for the outdoor adventures/fast pack

Planning for a backcountry trip can be intimidating… here is a guide on how to manage calories and weight while building your pack (with nutrition in mind).

Carbohydrates break down to glucose: essential for your brain, nervous system, and much of your physical motion (4 calories per gram).

Eating too few is just as bad as too little protein or fat. In a study of Everest, the carbohydrate intake was about 5g/kg -10g/kg depending on intensity.

Simple vs. Starchy (quick energy vs. sustained energy)

Protein: a major part of all cells, especially muscle cells. It breaks down to amino acids which are the building blocks of new cells and important for repairing tissue (muscles) and maintaining immune system.

  • 1.2-1.4g/kg for endurance training (4 calories per gram)

Fat: often undervalued, is a dense form of energy while hiking and due to the low intensity that predominates, ends up being a major fuel source (9 calories per gram).

For backpacking the goal is high calorie and low weight especially if you are going out for a few days to weeks.

Normally you consume around 2000 calories, but hiking all day you will need upwards of 4000 calories per day, how does this help? You can plan backwards now.

If you hike for 5 days that is 20,000 calories – to mitigate the weight and space you want to choose energy dense foods:

  • 20.5 pounds at 60 calories/ounce (hummus, tuna, dried apples)
  • 15.5 pounds at 80 calories /ounce (raisins, jerky, bagels)
  • 12.5 pounds at 100 calories/ounce (instant rice, Clif Bars, candied ginger)
  • 10.5 pounds at 120 calories/ounce (Pita chips, Jolly Ranchers, doughnuts)
  • 9 pounds at 140 calories/ounce (chocolate, peanut butter pretzels, Cheez-Its)
Picture Credit: REI.com

You want to optimize calorie per ounce!

If you don’t want to do all the math aim for a high fat to water ratio

  • Fat clocks in at 225 calories per ounce
  • Water is about 1 pound per 16oz  (if you know you can find a water source on the trail you can take less water too)

One easy way to maximize fat is to carry a small bottle of oil like olive oil to mix with your food. The other option is to look at Honeyville for freeze-dried cheese or butter to boost the calories but not the weight.

If you have the time and really want to experiment with making your own backpacking food Aaron is a RD that has developed lots of at-home dehydrated meals:


Some easy calorie boosting tips:

  • Replace non-fat milk with whole milk (NIDO) and coconut milk powders
  • Replace rice with protein-rich chickpea pasta and quinoa
  • Add whole nuts, nut butter, and nut powders to increase caloric density
  • Choose lower weight dehydrated fruits such as strawberries versus apricots
  • Include olive, coconut and sesame oils in recipes as much as possible (oil to be added on the trail)
  • Use a variety of beans as an additional protein source
  • Add in drink powders for calories and electrolytes (especially if it will be hot)

Purchased ultralight energy bar, snack and treat options:

  • Variety of Honey Stinger products – waffles, chews, and nut butter bars
  • Clif nut butter bars or Bobo’s Oat Bars
  • Pita chips, goldfish crackers, and cheese crisps
  • Variety of nuts
  • Homemade trail mix
  • Chocolate covered freeze-dried strawberries, limoncello almonds, homemade cookies
  • Chocolate covered coffee beans (for some added caffeine)
  • Justin’s Peanut Butter packets

So what would a day look like?

Sample 4000kcal day:

  • Breakfast: 2 packages instant oatmeal, 1 tablespoon full-fat powdered milk, 2 tablespoon chopped almonds, 2 tablespoon raisins, 2 tablespoon brown sugar, 1 teaspoon roasted flax seeds, 1 teaspoon chia seeds, with 1 oz New Primal bacon stick
  • Morning snacks:  1.4 ounce (37) gourmet jelly beans, 1 Clif Builder Bar, 1 ounce (28) Peanut M&M’s, 24 grams hydration powder mix (Drip Drop packet)
  • Lunch: 1 bagel (260) with individual cream cheese, 3 oz smoked salmon (200), 1 oz dried bananas and 1oz almonds
  • Afternoon snacks: 1.4 ounce (37) gourmet jelly beans, Pro Meal Bar, 1 ounce (18) cashews
  • Recovery drink such as Tailwind Recovery Drink
  • Dinner: 2 serving GOOD TO-GO Thai Curry 6.6oz (760 kcal), 1 package hot chocolate mix, 1 tablespoon full-fat powdered milk, 2 ounces dark chocolate

Kcals: 4000  |  Carbohydrates: 518g    |    Protein: 133g    |    Fat: 156g

Packaging in individual bags helps to portion out what you need so you stay on track!

Always pack a favorite treat of yours! Enjoy and stay safe (i.e. use bear bins and appropriate equipment).

Picture Credit: REI.com

Vitamin D – For Performance and Health

More Resources:

Chiang CM, Ismaeel A, Griffis RB, Weems S. Effects of Vitamin D Supplementation on Muscle Strength in Athletes: A Systematic Review. J Strength Cond Res. 2017 Feb;31(2):566-574. doi: 10.1519/JSC.0000000000001518. PMID: 27379960.

Owens DJ, Allison R, Close GL. Vitamin D and the Athlete: Current Perspectives and New Challenges. Sports Med. 2018 Mar;48(Suppl 1):3-16. doi: 10.1007/s40279-017-0841-9. PMID: 29368183; PMCID: PMC5790847.

Scott, JM, Kazman, JB, Palmer, J, McClung, JP, Gaffney‐Stomberg, E, Gasier, HG. Effects of vitamin D supplementation on salivary immune responses during Marine Corps basic training. Scand J Med Sci Sports. 2019; 29: 1322– 1330. https://doi.org/10.1111/sms.13467

CSA – Community Supported Agriculture

If you don’t know what this is don’t worry, I grew up on a Dairy and didn’t know fully what a CSA share until I worked at a farm in grad school that sold CSAs.

Essentially it is a system that connects the farmer and consumers by allowing the consumer to subscribe to the harvest of a certain farm or group of farms. It is an alternative socioeconomic model of agriculture and food distribution that allows the producer and consumer to share the risks of farming. In return for subscribing to a harvest, subscribers receive either a weekly or bi-weekly box of produce or other farm goods. This includes in-season fruits and vegetables and can expand to dried goods, eggs, milk, meat, etc. Typically, farmers try to cultivate a relationship with subscribers by sending weekly letters of what is happening on the farm, inviting them for harvest, or holding an open-farm event. Some CSAs provide for contributions of labor in lieu of a portion of subscription costs.

We are so used to getting any fruit or vegetable at any time of the year, which isn’t how farming works. Foods are seasonal. For better or worse (when you have 10lbs of chard to deal with).

Sometimes subscribing to a full CSA share can be intimidating (or expensive up front) and I will be honest with my work schedule I can’t always do it either. The good news is there are other options available. The one I have been enjoying is:

Full Circle

It combines convenience and local.

  • You can skip a week or cancel at any time
  • You can choose (to an extent) what goes into your box out of the seasonal options
  • You get to choose the amount (from a minimum)

The reason I wanted to write this is because as awesome it is, it isn’t always convenient when you are busy, and there are some easy ways to make sure you don’t waste your box or feel overwhelmed.

This week I got A LOT of chard, kale, and beets (seasonal)… the best thing you can do it wash and prep it right away.

As you can see from the picture below that is exactly what I did. Some ideas are:

  • Chop and freeze any greens you aren’t going to be able to use right away (kale, chard, spinach, beet tops) and use them in sauces, in stir-fry, or in a smoothie (my favorite)
  • Chop any other vegetables you can use that week so they are convenient (I chopped carrots and beets for salad, as well as some mushrooms), this way you can just toss everything together for a quick lunch salad
  • Lastly, this week I had so many beets that I went ahead and roasted some of them to add to salads and dinners this week.
  • Even with fruit, if I know I cant eat it all I will freeze them for smoothies or cobblers (did this last year with 10lbs of cherries)

Hope you try it out!

Misleading Media: Identical Twins Vegan vs. Omnivore Diet Outcomes

Recently this article came out:

Identical twins compared a vegan diet with meat-eating and found the vegan diet led to fat loss and more energy

Which got me thinking about how biased and misleading the media can be both in reporting and headlines, so I wanted to breakdown what is actually reported here.

From the Article:

The Turner twins, Hugo, left, and Ross, before comparing a vegan diet with an omnivorous diet in a 12-week experiment.

Overview of self-designed study design:

  • Randomized diet selection is not reported
  • Case study, n = 2, identical twins
  • Length: 12 weeks
  • Exercise: 5-6 days cardio with trainer
  • Diet: Almost isocaloric with food made by a chef delivery service (no macro/micronutrients reported)
  • Data points tracked: weight, cholesterol, muscle mass, subjective feeling, and microbiome
  • No extensive blood work was done
DietVeganOmnivore – Varied
Starting Weight (lbs)185175
Ending Body Weight (lbs)181189
Starting Body Fat13%13%
Ending Body Fat12%15%
Muscle Mass IncreaseNo reported10lbs
MicrobiomeDiversity decreasedDiversity decreased, but remained more consistent than Hugo’s
Subjective FeelingImproved energy later in the day and during gym session compared to before, but also notes he used to eat chips biscuits for snack which he traded for fruits and nuts   Libido dropped sharplyNone provided

Hugo states: “eating vegan forced variety”

Article reports key take-home: The twins concluded that their optimal diet is a mix of plant- and animal-based foods

— My Thoughts/Breakdown —

Game Changers has recently popularized athletes switching to a vegan diet, and the media has taken this and ran with it. That documentary is not the main topic of this post. To see a detailed review of the biases of the documentary click here: https://tacticmethod.com/the-game-changers-scientific-review-and-references/. This post is to breakdown the facts of this article vs. what is being promoted.

Although I find this research fascinating for a couple reasons, I also see the danger in how it was reported as detailed below:

  1. Twin case studies are a unique way to compare genetically identical individuals not often available in the literature. That being said it is a sample size of n=2 making extrapolation to larger populations difficult and dangerous.
  2. They aimed for an isocaloric diet to control that variable, although we are not given the macronutrient breakdowns and the fiber content, which is important for net calories and identifying changes in muscle mass between the two subjects. For example, 100 calories with 10g fiber is not all digestible and would result in lower net calories. Since vegan diets are traditionally high fiber due to the high plant content, it is likely that the vegan diet was lower net calories.
  3. Body weight is only reported for the vegan, but subtracting the 14 lbs (10lbs muscle, 4lbs fat) gained by the omnivore in the study puts his starting weight at 175 which is 10lbs lighter at the start of the study and is a significant difference.
  4. Although the headline reports body fat changes as a major benefit you can see from the results that the change in the vegan diet was 1%. From extensive work in body composition data, a 1% change in body composition is well within the area of standard area even with the most accurate machines. Additionally, Ross gained 10lbs of muscle, which is typically accompanied with small amounts of fat, explaining the increase of 2% body fat. Side note, muscle mass is an important characteristic for athletes, since muscle mass directly associated with force generation and velocity.
  5. Comprehensive blood work is not done, but they report cholesterol in the vegan diet dropping (typically seen with the increase in fiber in a diet) and the omnivore diet staying the same, although no specific numbers are reported.
  6. When comparing subjective reports the vegan diet is highlighted for increasing energy, although he admits he was eating processed snacks before and substituting fruit and nuts is a more blood sugar stable snack regardless of the rest of your diet, and more significantly he reports having decreased libido, which can be a sign of the body not producing enough testosterone which would eventually hinder performance. Dietary cholesterol is necessary to be able to produce testosterone. No subjective report was given to compare for the omnivore.
  7. Lastly, they compare microbiome reports, and although the research here is promising it is still in the beginning phases of research. Interestingly enough, both had a decrease in microbial diversity (number of bacteria species), typically associated with less resilience.

Overall you can see that although interesting, there is little evidence to support the headline that is flashed across web browsers and newspapers across the world, and more importantly, is misleading to the actual evidence that it does show. Even the subjects themselves say their ideal diet combines the best of both diets: the protein and cholesterol benefits from animal products and the variety and fiber from a vegan diet. We need to stop demonizing one side or the other. As with politics or anything, having a balance and understanding of the data is the key.


Milk and Milk Alternative Overview

Plant-based milks, similar to cow milk are mostly water (which may be why milk is one of the most hydrating beverages). Plant-based milks are derived mostly from soaking the nut/seed/grain in water and adding plant-based oils and gums for texture and natural flavors/sugars for taste. Most have calcium added and some have added soy or pea protein to meet the protein content of milk.

Plant-based alternatives have popped up due to the increasing lactose allergies that people are, although more and more people are drinking plant-based milks without any allergies. Is the switch “healthier”.

Let’s look at a breakdown:

There are 2 major things I look for when evaluating milks:

  1. Protein
  2. Added Sugars

As you can see the chart is sorted by PROTEIN because we know that protein (1) helps with satiety, (2) is important for keeping lean muscle on, and (3) because it balances blood glucose levels when consumed with a carbohydrate.

Based off this you can see that Fairlife milk wins the protein category (13g) followed by cow milk, Ripple milk, and Good Karma Flaxmilk all at 8 grams per cup.

From an added sugar perspective, I chose to analyze mostly ‘unsweetened’ varieties which cuts down the added sugars, but the new guy on the street ‘oatmilk’ has the highest carb content (although it does have 2 grams of fiber), so keep this in mind when you order a oatmilk latte next time (note: it is also not recommended for people who follow a low fod map diet due to high maltose). Cow milk is the next highest in sugar, although this is not added sugar it is from the lactose naturally found in milk, followed by original almond milk (or any plant-based milk you get that is not unsweetened).

Let’s look at cost per cup now:

Based off this, cow’s milk at $.30 per cup is actually still the best ‘bang for your buck’ and provides you with a good amount of protein. For athlete’s looking to get more protein in, Fairlife milk offers a reasonably priced ($.53), high protein, lower sugar option that is lactose-free. For those looking for a plant-based milk, Ripple Milk has the highest protein with lowest sugar content for just $.72 per cup.

But What about milk in my coffee…

It is hard to beat the texture and creaminess of cow milk in coffee, but if you are allergic or avoiding dairy there are plenty of options out there now. Oatmilk wins the plant-based milk contest for texture and creaminess in coffee, although keep in mind it has 50% more calories in it. Almond milk and soy milk are probably the second most popular in lattes, but keep in mind they are typically using higher fat plant-based milks and ones that are sweetened. Although every place is different, you can always ask the barista. Here is a breakdown of some of the more commonly ordered beverages with milk/alternative milk (note: no syrups added).

What’s the latest research in Nutrition and Immunity

GSSI – Walsh, 2019

The most common question I get asked around this time of year is, “how can I not get sick?”. While most people are often looking for some elaborate response, my reply is very simple – “Reduce your stress and get more than 7 hours of sleep so that your body has the strength to resist and fight off illness”. While the answer seems basic and (to some) maybe disappointing, I’ll expound a bit on the details below and discuss some of the things that expose us to a greater risk of getting sick and basic strategies you can follow to help mitigate this risk, as reported in a large GSSI publication.

Factors that increase the risk of sickness:

  1. Fall and winter – common cold and flu season
  2. Poor hygiene and exposure to sick people
  3. Recent symptoms
  4. Air travel
  5. Poor sleep
  6. Life stress, depression, anxiety
  7. Low energy availability
  8. Increases in training load

Strategies for combatting sickness:

  1. Try to avoid sick people
  2. Ensure good hygiene and proper vaccination
  3. Avoid exposing yourself by touching eye, nose, mouth
  4. Don’t train with below the neck symptoms
  5. Manage all stress
  6. Aim for >7 hours of sleep
  7. Eat a well-balanced diet

Finally, around this time of year, supplements are always a hot topic. Everything from essential oils to supercompensation of vitamin C has been recommended for resistance to infection, but what does the research show?

  1. Zinc Lozenges (Hemilia, 2017)
    1. Zinc ions in oral lozenges inhibit rhinovirus replication and have antioxidant effects.
    1. Benefit: decrease duration of the Upper Respiratory Tract Infection (URTI) by 33%. Side effects, bad taste.
    1. Suck on Zinc Lozenges – 80mg/day which would be about 15 lozenges.
  2. Probiotics (Cox et al. 2010)
    1. These live microorganisms modulate immunity. Live microorganism administered orally for several weeks, can increase the number of beneficial bacteria in the gut.
    1. A cochrane review shows about a 50% decrease in URTI incidence and 2 day shortening of URTI. (Hao, Dong, Wu, 2015)
    1. Take 2 pills per day. Thorne FloraMend Prime has the correct strands.
  3. Vitamin D (Berry et al. 2011) (He et al. 2013)
    1. Vitamin D is an anti-inflammatory, essential fat-soluble vitamin. It influences innate immunity and has anti-inflammatory effects. Skin exposure to sunlight accounts for 90% of the source of vitamin D.
    1. Meta-analysis showed protective effects for vitamin D for URTI. Deficiency associated with longer lasting URTI in athletes. Monitoring required.
    1. Recommend 1000mg/day D3 from Thorne
  4. Vitamin C (Hemelia and Chalker, 2013)
    1. Vitamin C is a water soluble antioxidant vitamin that quenches ROS.
    1. A cochrane review of 5 studies in heavy exercisers shows about 50% decrease in URTI taking vitamin C .25-1g/day. The literature is unclear as to whether Vitamin C blunts adaptation in well-trained athletes. (Hemelia and Chalker, 2013)
    1. To stay on the food side and avoid the detrimental effects to blunting adaptations with excess vitamin C, drink 1 – 16oz bottle 100% Orange Juice.
  5. Polyphenols (Walsh, 2018)
    1. Polyphenols are anti-inflammatory, plant flavonoid, antioxidants. In vitro studies have shown strong anti-pathogenic effects following polyphenol ingestion.
    1. Meta-analysis of 14 studies show some reduction in upper respiratory infection (URTI), including during intensified training. However, there remains limited evidence for its enhanced influence on immunity.
    1. While the results of polyphenols on immunity remain unclear, increase your consumption of grapes, pistachios, cranberries, blueberries will help to boost your resveratrol intake.

So… What does this all mean…

Practical Guidelines to Maintain immunity

  1. Eat a well-balanced diet – lots of color and variety
  2. Ensure adequate protein intake (1.2-1.7g/kg/day)
  3. At the onset of cold take zinc lozenges (75mg/day)
  4. Consider taking probiotics for illness prone/travelling (greater than 10 billion bacteria/day)
  5. Consider 1000IU Vit D3
  6. Consider vitamin C for illness prone/traveling and during intense competition >200mg/day


1. Walsh, N.P. (2018). Recommendations to maintain immune health in athletes. Eur. J. Sport Sci.18:820-831.

2. Hemila, H. (2017). Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. J.R. Soc. Med. Open 8:2054270417694291.

3. Hemila, H., and E. Chalker (2013). Vitamin C for preventing and treating the common cold. Cochrane Database Syst. Rev.:CD000980.

4. Cox, A.J., D.B. Pyne, P.U. Saunders, and P.A. Fricker (2010). Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes. Br. J. SportsMed. 44:222-226.

5. Berry, D.J., K. Hesketh, C. Power, and E. Hypponen (2011). Vitamin D status has a linear association with seasonal infections and lung function in British adults. Br. J. Nutr. 106:1433-1440.

6. He, C.S., X.H. Aw Yong, N.P. Walsh, and M. Gleeson (2016). Is there an optimal vitamin D status for immunity in athletes and military personnel? Exerc. Immunol. Rev. 22:42-64.

Probiotics and Athletes

Jäger R, Mohr AE, Carpenter KC, Kerksick CM, Purpura M, Moussa A, Townsend JR, Lamprecht M, West NP, Black K, Gleeson M, Pyne DB, Wells SD, Arent SM, Smith-Ryan AE, Kreider RB, Campbell BI, Bannock L, Scheiman J, Wissent CJ, Pane M, Kalman DS, Pugh JN, Ter Haar JA, Antonio J.,  International Society of Sports Nutrition Position Stand: Probiotics. Journal of the International Society of Sports Nutrition. Dec 21;16(1):62. 2019.

‘Probiotics’ has become a trendy word that you see added to all sorts of foods and marketed to all types of people for a wide variety of reasons. With all the information out there I wanted to give a summary from the latest position stand of what the latest research on probiotics in athletes has shown and what the recommendations are. Spoiler alert, we still need a lot more research in this area.

To know why probiotics may be important for humans, we first need to know what our microbiome is, and Harvard Public Health does a good job breaking Ursell’s research down:

Picture a bustling city on a weekday morning, the sidewalks flooded with people rushing to get to work or to appointments. Now imagine this at a microscopic level and you have an idea of what the microbiome looks like inside our bodies, consisting of trillions of microorganisms (also called microbiota or microbes) of thousands of different species. These include not only bacteria but fungi, parasites, and viruses. In a healthy person, these “bugs” coexist peacefully, with the largest numbers found in the small and large intestines but also throughout the body. The microbiome is even labeled a supporting organ because it plays so many key roles in promoting the smooth daily operations of the human body.

Each person has an entirely unique network of microbiota that is originally determined by one’s DNA. A person is first exposed to microorganisms as an infant, during delivery in the birth canal and through the mother’s breast milk. Exactly which microorganisms the infant is exposed to depends solely on the species found in the mother. Later on, environmental exposures and diet can change one’s microbiome to be either beneficial to health or place one at greater risk for disease.

The microbiome consists of microbes that are both helpful and potentially harmful. Most are symbiotic (where both the human body and microbiota benefit) and some, in smaller numbers, are pathogenic (promoting disease). In a healthy body, pathogenic and symbiotic microbiota coexist without problems. But if there is a disturbance in that balance—brought on by infectious illnesses, certain diets, or the prolonged use of antibiotics or other bacteria-destroying medications—dysbiosis occurs, stopping these normal interactions. As a result, the body may become more susceptible to disease.

What are probiotics and where are they found:

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (host meaning your gut microbes)

To break it apart literally it means:

Pro – for

Biotic – life

They are described by: genus, species, and strain

            Ie. Lactobacillus acidophilus SPP (commonly found in yogurt)

Reported in CFUs on labels – colony forming units

Ie. 10 million CFUs

They are found naturally in fermented foods like: yogurt, kombucha, kefir, sauerkraut, miso, and some pickled vegetables. (Sorry, yes beer is fermented but the live microorganisms are killed in the beer making process – always look for labels that say ‘live and active cultures)

They were first research for their reported health benefits on the supporting/improving of the immune system, maintenance of the intestinal barrier, fight against pathogen adhesion to host tissue, and production of different metabolites such as vitamin, minerals, short chain fatty acids, and molecules that act as modulators in the gut-brain axis communication.

What is the microbiome? | ADC Education & Practice Edition

The body of research is growing in athletes and probiotics:

  • Studies are now looking at the effect on: gut health, exercise performance, recovery, physical fatigue, immunity, and even body composition (based on positive rat studies)

On the flip side things that improve your microbiome outside of probiotics:

  • Exercise has a positive relationship on gut biodiversity (your microbiome)
  • Protein has a strong positive impact on the microbiota
  • Carbohydrates are well known for their profound effect on the gut microbiota with fiber (coming from whole grains and fruits/vegetables) associated with microbial richness and diversity

Benefits of Probiotic supplementation that are being researched:

One thing we know of athletes with high training volume – Strenuous and prolonged exercise places stress on the gastrointestinal (GI) tract and increases the likelihood of multiple symptoms associated with a disturbance of gut microbiota (ie. Diarrhea, bloating, cramps, etc.) and decreased performance.

The GI tract is also heavily protected by the immune system as it is a major gateway for pathogens, therefore much research has been done on probiotics defense against upper respiratory tract infections (URTI).

Probiotics may also regulate mucosal immune response, improve macrophages (pathogen fighters), and modulate expression of genes associated with macrophage activity.

Although this all seems promising it is important to remember: research is quite new in athletes

  • Of the 24 studies – 17 reported null effects and 7 reported significant improvements
  • With multi-strain probiotics seeming to have more positive effects than single strain

Within those studies some of the positive results are below:

  • Lactobacillus planetarium has been shown to activate cell growth signaling pathways in gut enterocytes which in turn increases protein metabolism in the gut as well as maintain gut permeability (essentially they control of what passes through the gut wall)
  • Bacillus coagulans GBI-30, 6086 enhances the health of the cells of the gut lining through improved nutrient absorption including minerals, peptides, and amino acids by decreasing inflammation and encouraging optimum development of the absorptive area of the gut villi. They have been shown to increase protein absorption (Kimmel et al. 2010) (Maathuis et al., 2010) when added to a protein post-workout drink.
  • B. subtilis – no performance improvement, but lower serum TNF-alpha concentrations (which is your immune system regulator – concentrations are typically higher in the case of infection/illness).
  • Although a few studies have found multi-strain probiotics increase VO2 max, aerobic power, training load, and time to exhaustion, more studies have found no such effect.
  • The effect of probiotics on body composition is mixed, and many of the studies are poor study design, as of now the research is lacking.

Let’s talk about the Immune System:

The mucosal lining of the GI tract is the first-line-of-defense against invading pathogens and is an important border with the host immune system with approximately 70% of the immune system in the gut.

Mucus Production - Regulation - TeachMePhysiologyTeachMePhysiology

Exhaustive exercise is known to negatively impact immunity.

Therefore, many studies have focused on this effect of probiotics and immuity:

  • Of the studies on athletes and immune system (22), 14 showed significant improvement and 8 showed no effect.
  • B. animalis ssp. Lactis Bi-07 in active people showed 27% reduction in URTI episode and 0.8 month delay in time to illness
  • However, most studies are conducted on endurance athletes
  • Note: The body of evidence favors probiotics in reducing URTI, however there is large differences in stains used, duration, population, and effects measured.

The beneficial effect from probiotics on incidence of URTI is possibly linked to enhanced systemic and mucosal immunity.

In summary for the immune system, probiotic supplementation may be viable to support immune function during intense training.

Let’s talk about GI tract health

Exercise induced redistribution of blood can result in splanchnic hypoperfusion (meaning blood is diverted from the abdominal region and your gut) as a possible mechanism for gut dysfunction or the up and down movement of running can increase the frequency of gut symptoms.

Disruptions in the GI system can impair the delivery of nutrients and may affect performance.

Of the 10 studies, 6 reported no effects – 4 reported positive effects

  • In the positive results, zonulin and endotoxin concentrations were reduced (markers of gut permeability).
  • Several lactobacillus species have been noted to increase mucin expression in human intestinal cell lines and thus may help restore mucus layer.
  • Adhesion of probiotics to the intestinal mucosa have shown to favorably modulate the immune system and the fighting of pathogens by preventing pathogen binding and creating a hostile environment that may inhibit the colonization of pathogenic bacteria.

Probiotic Safety:

They have been used safely in foods and dairy products for over 100 years in adults and infant formula (unknown in vulnerable population)

It is important if you are looking to take supplements that you take a reputable brand (and NSF certified if possible). Many probiotics, when tested, didn’t have the stated amount or strains in them.

Most Studied:

  • Bifidobacterium (ssp. Adolescentis, animalis, bifidum, breve, longum
  • Lactobacillus (ssp. Acidophilus, casei, fermentum, gasseri, johnsonii, reuteri, paracasei, plantarum, rhamnosus, and salivarius

International Olympic Committee recognizes benefits of probiotic supplementation with a daily dose of 1 x 10 billion taken for 14 days prior to competition or event.

Duration of effect: After 8 days of ceasing probiotic intake levels reduce back to non-detectable in the gut so they only are effective if you are taking them

Timing or consumption: 30 minutes before a meal or with a meal – improves bacterial survival rate (also better taken with milk or oatmilk)

Probiotic supplementation is more likely to alter the microbiome composition of dysregulated microbiomes compared to healthy ones, like in the case of diarrhea or antibiotic use.


Research in athletes shows promising benefits for immune and gut health.

Here is a quick guide to which probiotic may be beneficial and when:

L. acidophilusTreat travelers and antibiotic relatedCertain brands of yogurt and milk, miso and tempeh and supplements
L. helveticus and B. longumImmune and psychological healthKefir, Yogurt, fermented cheeses and supplements
L. plantarumPsychological health, increased immunity and improved metabolic conditions, preliminary research on endurance performanceKimchi, fermented beets, pickles cucumbers, and sauerkraut, and supplements
L. reuteriReduce inflammation and allergiesFermented vegetables, dairy products and supplements  
L. rhamnosus GG, or LGG,  Most effective probiotic in treating infectious diarrheaKefir, Kombucha, yogurt, and supplements
B bifidumHopeful treatment for certain GI conditions, such as constipation, traveler’s diarrhea, IBS, ulcerative colitis and H. pylori  Kefir, yogurt, buttermilk, miso, tempeh, pickles, kimchi, cured meats, sauerkraut and sourdough, and supplements
S. boulardii (yeast)Used for years to treat several gastrointestinal conditions, including travelers’ diarrhea and C. diffSupplement
B coagulansBeneficial effects on protein and other nutrient absorptionSupplement
L rhamnosus B bifidum, B lactis, E faecium, L acidophilus, L brevis, and L lactis L salivariusLinked to improved gut health in athletesSupplements and yogurts
L fermentum L casei L delbrueckii bulgaricus, B bifidum, and S salivarus thermophilus (in yogurt drink) B animalis lactis L gasseri, B bifidum, and B longum B bifidum, B lactis, E faecium, L acidophilus, L brevis, L lactis L helveticus LaftiHave been shown to improve immune health in athletesSupplements and yogurts
B. animalis ssp. Lactis Bi-07Reduce URTI by 27%Dairy products and Supplements


The Nutrition Source, Harvard Public Health. Microbiome. https://www.hsph.harvard.edu/nutritionsource/microbiome/

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Maathuis AJ, Keller D, Farmer S. Survival and metabolic activity of the GanedenBC30 strain of Bacillus coagulans in a dynamic in vitro model of the stomach and small intestine. Benef Microbes. 2010 Mar;1(1):31-6. doi: 10.3920/BM2009.0009.

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