News Quickie: Vitamin D Could Increase IGF-1 Delivery to the Muscle. Plus: Ergogenic Juicing For Ultra-Marathoners

Marathon de Sable ➯ Tomato juice

It's about time for another quickie, a news quickie about exercise & supplementation, about vitamin D and tomato juice... actually it's rather about tomato juice, a special carbohydrate + protein bar and the notorious "Gatorate(R)-ish" carbohydrate supplement every endurance athlete believes he must be taking. But let's be honest, who cares about tomato juice, carbohydrate, protein bars, pseudo Gatorade and their individual and joint effects on the health and performance of constantly (over-)taxed ultra-marathoners, if the other new item in today's article deals with the potential beneficial effect of vitamin D on IGF-1 and its anabolic consequences?
You care? Ok, in that case, you may be inclined to hear that the bar contained 30.20 g (19.7 g sugars) carbohydrates, 5.2g fiber, a surprisingly high amount of fat (15.6g) and. of course, protein 30.8g to be precise (14.3 g whey protein). If we add the energy content of carbs, fats and protein up, we get an energy content of ~400kcal for the bar and thus approx 24x more than in 100ml of the tomato juice, which is - as you can see in Table 1 more or less devoid of "nutrients", but packed with antioxidants.

Table 1: Average nutritional value per 100 g of tomato juice and protein bar used in the present study (canned, salt added) and the carbohydrate supplementation beverage, as provided by the manufacturer (Samaras. 2014)

As you can see in Figure 1, enough antioxidants to elicit significant increases in flow-mediated dilatation, which was used as an estimate of endothelial function, by the researchers from the  General Hospital of Giannitsa in Greece.

Figure 1: Changes (% pre) in response to tomato juice & protein bar supplementation (Samaras. 2014)

Interestingly, the thiobarbituric-acid reactive substances, and protein carbonyls were significantly decreased in both supplementation groups - a good indicator that these changes were not mediated by the red night-shade elixir, but rather by the protein + carbohydrate bar, which lead to a "whey-typical" increase in reduced glutathione.

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If the marathoners had now had low vitamin D levels, they may even had gained some muscle, if they had followed a similar protocol as the subjects in another recently published study from the St. John Fisher College Rochester NY.

And the results of this study don't even seem completely nonsensical. As a SuppVersity reader you do after all know about the existing evidence of the negative effects low vitamin D levels will have on the function and strength of skeletal muscle ("low" in this context means less than 30ng 25-OHD on the lab report). Against that background, it does after all appear to be logical that refilling the levels would in one way or another help maintain or even build skeletal muscle.

The actual news here is yet not that vitamin D could potentially prevent muscle atrophy and increase hypertrophy. It's rather that these effects could be brought about by the significant increases in total IGF-1, as well as the IGF-1 binding proteins 1 + 3 researchers from the College of Rochester observed, when they added 4,000 IU of vitamin D to the diets of 6 vitamin D insufficient and deficient men (39.0±8.6yo with 25OH D 20.0±7.7ng/mL) who participated in a one-hour exercise program consisting of stretching (ST), aerobic (AB), and resistive (RT) exercises (Darr. 2014)

Suggested Read: "Underestimated Vitamin D Sources: Especially Eggs, But Also Chicken, Pork, Fish & Dairy Contain an Overlooked, Physiologically Relevant Amount of Ready-Made 25OHD" | more

The aerobic training was a intensity treadmill walk, which was rotated with a moderate strength (50% 1-RM, 15, 10 repetitions) full body workout consisting of squats, bench presses, leg presses, and lat pull downs. As previously said, the scientists found that the vitamin D binding protein 3 levels (BP3) were increased after the resistance training in the vitamin D (n=6) vs. placebo (n=7) group (30%). And while the total IGF-1 levels decrease in the placebeo group, the increase in various binding proteins buffered this effect in the vitamin D group. Similar, yet less pronounced effects were observed in response to the aerobic training.

Whether the scientists' assumption that the increases in BP3 and BP1 levels and the maintenance of the total IGF-1 levels "potentially alter [...] the IGF system for enhanced muscle health" is accurate, let alone practically relevant is something this study cannot actually confirm.

And let's be honest, is it even likely? For someone without a pre-existing vitamin D deficiency? No. For someone with similarly low vitamin D levels as the deficient and insufficient subjects in a 2011 study by Stockton et al. (2011)? Probably, yes - but are you actually D-ficient?
References:

• Ceglia, Lisa, et al. "Effects of alkali supplementation and vitamin D insufficiency on rat skeletal muscle." Endocrine 44.2 (2013): 454-464.
• Darr, Rachel, et al. "Vitamin D supplementation effects on the IGF system in men after acute exercise (828.15)." The FASEB Journal 28.1 Supplement (2014): 828-15.
• Samaras, Antonios, et al. "Effect of a special carbohydrate-protein bar and tomato juice supplementation on oxidative stress markers and vascular endothelial dynamics in ultra-marathon runners." Food and Chemical Toxicology (2014).
• Stockton, K. A., et al. "Effect of vitamin D supplementation on muscle strength: a systematic review and meta-analysis." Osteoporosis international 22.3 (2011): 859-871.