ONLINE DRIVERS MEDIA

Yogurt & Co are good for athletes. But is this due to the bacteria?

As a regular here at the SuppVersity, you are well aware of the far-reaching effects of having the "right" or "wrong" bacteria in your tummy. The claim that having the "right" bacterial make-up in the gut could have beneficial effects on your performance in the gym or on the track is something you should not believe too credulously. If we had a study to prove these benefits, things would be different, though - a study like the one a group of researchers from the National Taiwan Sport University are about to publish in the scientific bible of resistance training, the Journal of Strength and Conditioning Research (Hsu. 2014).

In said study which is still available only as an accepted manuscript, Hsu et al. investigated the association of intestinal bacteria and exercise performance in specific pathogen-free (SPF), germ-free (GF), and Bacteroides fragilis (BF) gnotobiotic mice (animals in which only certain known strains of bacteria and other microorganisms are present).
To this ends, the scientist had the rodents swim to exhaustion to determine whether enteric bacteria alter antioxidant enzyme levels, exercise performance and physical fatigue. In addition, they tested the antioxidant enzyme activities, physical performance and anti-fatigue function after monocolonizing GF mice with B. fragilis (BF).

Figure 1: Time to exhaustion during exercise test and body composition of the miceaccording to the make-up of their gut microbiome; data expressed relative to group means (Hsu. 2014)

What they found was an increased time to exhaustion for the previously germ-free (GF) mice after theyd been colonized with B. fragilis (BF). Similar results were observed for the specific pathogen-free and Bacteroides fragilis gnotobiotic mice, who were also more enduring than the obesity resistant (Bäckhed. 2007) germ-free mice.
As any SuppVersity veteran would expect, the germ-free mice were leaner than the rest of the pack. At the same time, the "sterile" mice did yet also have a lower liver, muscle, brown adipose, and epididymal fat pad weight than the SPF and BF mice.

Figure 2: Selected markers of antioxidant status in serum and liver; expr. rel. to group means (Hsu. 2014)

The markers of antioxidant defenses, the scientists measured were highest in the lean + light germ-free mice and their specific pathogen-free cousins. Against that background its at least somewhat surprising that the performance differences are pretty significant.
References:

• Bäckhed, Fredrik, et al. "Mechanisms underlying the resistance to diet-induced obesity in germ-free mice." Proceedings of the National Academy of Sciences 104.3 (2007): 979-984.
• Cani, Patrice D., et al. "Gut microbiota fermentation of prebiotics increases satietogenic and incretin gut peptide production with consequences for appetite sensation and glucose response after a meal." The American journal of clinical nutrition 90.5 (2009): 1236-1243.
• Cox, Amanda J., et al. "Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes." British Journal of Sports Medicine 44.4 (2010): 222-226. 
• DiMarco, N. M., et al. "A–Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance—Part 30." British journal of sports medicine 46.4 (2012): 299-300.
• Gleeson, Michael, et al. "Daily probiotics (Lactobacillus casei Shirota) reduction of infection incidence in athletes." (2011). 
• Hsu et al. "Effect of Intestinal Microbiota on Exercise Performance in Mice." Journal of Strength and Conditioning Research.  DOI: 10.1519/JSC.0000000000000644 | Publish Ahead of Print.
• Martarelli, Daniele, et al. "Effect of a probiotic intake on oxidant and antioxidant parameters in plasma of athletes during intense exercise training." Current microbiology 62.6 (2011): 1689-1696.
• West, Nicholas P., et al. "Lactobacillus fermentum (PCC®) supplementation and gastrointestinal and respiratory-tract illness symptoms: a randomised control trial in athletes." Nutrition journal 10.1 (2011): 30.

Taking vitamin D pills on their own may be less effective than taking them with a meal containing 30% of the calories from fat - at least for older men & women and high doses of vitamin D3

This is science. Only 6 months ago, I wrote in an article about the effects of fat on the absorption and bioavailability of fat soluble vitamins that vitamin D would be the fat soluble vitamin with the lowest dependence on the co-administration of fat. Rather than the amount, it appeared as if the change in plasma 25OHD (nanograms per milliliter) during vitamin D supplementation was rather associated with the types of fat, i.e. MUFA = increased absorption vs. PUFA = decreased absorption (Niramitmahapanya. 2011).

Now, half a year later, it appears as if another, previously overlooked variables would force me to reformulate previous recommendations: Age and dosage!
In contrast to previous studies, Bess Dawson- Hughes and colleagues investigated the influence of fat on the absorption of vitamin D3 in older, not young men and women. In that, inclusion criteria for the study were

• no use of not more than 400 IU vitamin D or 1,000 mg calcium per day,
• serum 25(OH)D level in the range 20 to 29.5 ng/mL (49.9 to 73.6 nmol/L),and
• a body mass index in the range 20 to 29.5 (normal weight)

Subjects with kidney problems, hypercalcemia, general issues with malabsorption, Crohn’s disease, disorders of bone metabolism, kidney stones, cancer and those who were using proton pump in hibitors, lipid-lowering medications, fish oil, or flaxseed oil, hormones, osteoporosis medications, or high-dose thiazide diuretic therapy were equally excluded as those subjects who attended tanning salons, regularly.
This was yet not the only difference. Next to the subjects age, the amount of vitamin D3 in the capsules the subjects received differed, as well. While previous studies that reported little to no effect of fat on the absorption of vitamin D3 used small(er) amounts of vitamin D, like 1,000, 2,000 or 5,000 IU per serving, Dawson-Hughes et al. used a single serving of 50,000 IU(!) and thus more than 10x higher dosages than previous studies.

Figure 1: Composition of the test breakfast, lunch, and dinner meals, expressed as % of total energy the 50 healthy older adults consumed in the study at hand (Dawson-Hughes. 2014)

Alongside said vitamin D3 super-dose all 50 subjects ingested one out of three randomly selected meals that were either fat free or contained 30% of the total calories in form of dietary fat - albeit at two different PUFA:MUFA ratios (see Figure 1)

"[The m]eals were provided by the metabolic kitchen and consisted of real food. For example, breakfast consisted of egg whites flavored with small amounts of onion and tomato, fruit, toast, and cranberry juice. The groups were balanced for energy by adjusting the amount of sugar in the cranberry juice (diet or regular juice or a mixture of the two). Protein and fiber were balanced across all groups. MUFA:PUFA was manipulated by adding varying amounts of MUFA (olive oil) and PUFA (corn oil) to achieve a ratio of 1:4 in the low and 4:1 in the high MUFA:PUFA diets. The boxed lunch and the dinner provided to the study subjects on the test day had fat/protein/carbohydrate content similar to that of the test breakfast meals.

Importantly, the subjects were required to (a) eat all of the food provided and (b) refrain from pigging out on anything that was not on the menu for the study day.

Figure 2: Serum vitamin D3 levels in subjects after consuming fat-free or -containing meals (Dawson-Hughes. 2014)

What the scientists found, when they analyzed the vitamin D response of the subjects depending on (a) the fat content and (b) the type of the fat, Dawson-Hughes et al. found:

• In analyses of vitamin D absorption at baseline and the three follow-up time points, there was a significant interaction of fat-free vs fat-containing meal group with time (P < 0.001). As shown in [figure 2], there was no significant difference in plasma vitamin D-3 levels at baseline, but the fat-containing meal group had significantly higher plasma vitamin D-3 concentrations than the fat-free meal group at each time point thereafter.
  
  At 12 hours, the fat-containing vs fat-free meal mean difference in plasma D-3 concentration was 26.9 ng/mL (95% CI 9.6 to 44.1 ng/mL) (69.9 nmol/L). Differences at the other time points were for 10 hours, 30.5 ng/mL (95% CI 14.4 to 46.7 ng/mL) (79.3 nmol/L) and for 14 hours, 21.3 ng/mL (95% CI 4.6 to 37.9 ng/mL) (55.4 nmol/L).

• Vitamin D-3 levels at 12 hours after the dose were 116.0 3 ng/mL (301.5 nmol/L) in the low MUFA:PUFA group and 104.2 ng/mL (270.8 nmol/L) in the high MUFA: PUFA group.
  
  Potential covariates, body mass index, total body fat mass, and screening plasma 25(OH)D level were not associated with vitamin D absorption and neither modified the effect of fat on vitamin D absorption.

As the researchers point out, "[t]here were no serious adverse events during the study" and "[c]ompliance with the vitamin D supplement was 100%" (Dawson-Hughes. 2014). So, non of these obvious, but undesirable confounding factors could explain the observed differences between (a) the non-fat vs. fat-meals and (b) the influence of the PUFA:MUFA ratio.
References:

• Dawson-Hughes, Bess, et al. "Dietary Fat Increases Vitamin D-3 Absorption." Journal of the Academy of Nutrition and Dietetics (2014).
• Niramitmahapanya, Sathit, Susan S. Harris, and Bess Dawson-Hughes. "Type of dietary fat is associated with the 25-hydroxyvitamin D3 increment in response to vitamin D supplementation." The Journal of Clinical Endocrinology & Metabolism 96.10 (2011): 3170-3174. 
• Wortsman, Jacobo, et al. "Decreased bioavailability of vitamin D in obesity." The American journal of clinical nutrition 72.3 (2000): 690-693.