2909 IU of Vitamin D3 per Day - That's What Mr. Average Needs | What Do You Need? 3094, 4450, or 7248 IU/day?

Your BMI or rather the associated level of inflammation and bodyfatness determines your D3 requirements.

I know that I have previously written about estimated vitamin D requirements, but in contrast to previous articles that were based only on 1-3 studies, today's article about the purported vitamin D requirements of the average Westerner, however, is based on the same previous 108 published estimates and new calculations based on the vitamin D status of 13,987 individuals in various studies Veugelers, Pham and Ekwaru used as the observational database for what is a of now probably the most tangible vitamin D recommendation in their recently published study in Nutrients (Veugelers. 2015).

There are many ways to get your vitamin D learn more the SuppVersity

How Much To Take?

Leucine, Insulin & Vitamin D

Vit. D Speeds Up Recovery

Overlooked D-Sources

Vitamin D For Athletes!

Vitamin D Helps Store Fat

Now, as the headline already tells you, their analysis of said data lead the researchers to conclude that "2909 IU of vitamin D per day is needed to achieve serum 25‐hydroxyvitamin D (25(OH)D) concentrations of 50 nmol/L or more in 97.5% of healthy individuals" (Veugelers. 2015). To get to this value, the researchers from the University of Alberta used quantile regressions to

"model the effect of vitamin D supplementation on the 2.5th percentile, the median and the 97.5% percentile of serum 25(OH)D concentrations [and an] exponential model [and] logistic regression [for the estimates and] to estimate the probability of having serum levels above a lower and below an upper serum 25(OH)D concentration, [respectively]" (Veugelers. 2015). 

In that it is important to know that in this model the limit of the 'normal' vitamin D concentrations (58-171 nmol 5(OH)D/L) was defined in accordance with the values Luxwolda et al observed in traditionally living populations in East Africa who have mean serum 25‐hydroxyvitamin D concentration of 115 nmol/l or more (Luxwolda. 2012). So, we are not talking about absolute minimum levels, but rather about levels many researchers would call "optimal".

Figure 1: Plot of the results of the model calculations (left) and my visualization (right) of the calculated vitamin D requirements in IU/day for normal-weight, overweight and obese individuals (Veugelers. 2015).

As a SuppVersity reader you will be aware that normal-, overweight and obese subjects will need different amounts of supplemental vitamin D3 to achieve these "optimal" levels. To accomdate for these differences and to provide adequate estimates for normal weight, overweight and obese participants, Veugelers et al conducted separate analysis and used suitable logistic regression models to identify the log term of supplementation that provides the best fit. Needless to say that this sub-analysis was conducted based only on those studies that either included exclusively normal-, overweight or obese subjects or distinguished between the three of them yielded. It is thus only logical that this analysis yielded different results of which the 3094 IU/day, which is the suggested daily amount of vitamin D3 to maintain optimal vitamin D levels for normal-weight individuals, is yet pretty much identical to the previously cited "optimum" for Mr. Average Joe.

Against that background, it is yet all the more important to note that the average overweight or obese Westerner will yet need significantly more vitamin D3, 4450 IU/day and 7248 IU/day, to be precise, to keep his / her labels stable. Based on what you should remember from the role of 25OHD as an anti-inflammatory acute phase reactant (Waldron. 2014), though, this is not really surprising.

So what's the verdict, then? While the study at hand certainly provides the hitherto best estimate of our individual vitamin D3 requirements, I still wouldn't put blind faith into the results of Veugelers' model calculation. To be sure you're not too extra-ordinary to be average, I would suggest you test your 25OHD levels after 6 months on the suggested dosage. If you're "in the zone", everything is fine. If not, adjust appropriately.

Fat loss will trigger decent increases in vitamin D, but vitamin D will not trigger significant fat loss | more

Apropos adjusting, as the authors point out, the previously discussed figures may not even be the most practically relevant result of the study. Rather than that, it is the "large extent of variability in 25(OH)D concentrations" of which the authors rightly say that it "makes a RDA for vitamin D neither desirable nor feasible" (Veugelers. 2015) that's the most relevant results of the study.

And yes, you've read that right. The 400, 600 and 1000 IU/day RDA you will find in different countries all over the world is total bogus, not just because it is too low, but because stating a recommended daily allowance based only on the age, not the weight, or rather inflammatory status of an individual, is absolute bogus | Comment on Facebook!

References:

• Luxwolda, Martine F., et al. "Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l." British Journal of Nutrition 108.09 (2012): 1557-1561.
• Veugelers, Paul J., Truong-Minh Pham, and John Paul Ekwaru. "Optimal Vitamin D Supplementation Doses that Minimize the Risk for Both Low and High Serum 25-Hydroxyvitamin D Concentrations in the General Population." Nutrients 7.12 (2015): 10189-10208.
• Waldron, Jenna Louise, et al. "Vitamin D: a negative acute phase reactant." Journal of clinical pathology (2013): jclinpath-2012.

Health & Exercise Quickie: Vitamin D Deficiency, Taurine & Glycine. Multiple Sclerosis & Epstein-Barr. Paracetamol & Muscle Gains. Gender & Fatigue from Workouts. HIIT, LISS & Appetite. Plus: Scientists Debate: Light vs. Heavy Weights

While there is a positive trend in the percentage of US adults who meet the 2008 federal physical activity guidelines according to which they have to "devote at least 150 minutes/week to moderate, or 75 minutes/week to vigorous intensity exercise, or an equivalent combination", the number of people who have gotten the message that a combination of both strength and aerobic training (red line) is much more efficient than doing just aerobics (blue line) remains the same (CDC. 2012)

48%! That's the SuppVersity figure of the week and the percentage of US adults aged 18 and over who met the 2008 federal physical activity guidelines for aerobic activity in 2012 - that's 5% more than in 1997. It would be better to see it up in the 75%+ region, but it's nice to see that more and more people are devoting at least 150min/week to moderate intensity exercise, or 75 minutes/week to vigorous intensity exercise, or an equivalent combination.

What's not so nice is that people are still way too focused on aerobics and the number of US citizens that's combining resistance and aerobic training to reach their exercise goals is stagnating below 20%. Moreover, best-agers and baby boomers, who would probably benefit even more from some weight lifting than the 36% of the young men (age 18-24) who make up the lion's share of the 'real' physical culturists who know about the importance of both, 'weights' and 'cardio', are - if they work out at all - still sticking to the tried and disproven LISS only regimen.

On Short Notice, today: A Health & Exercise Quickie

Apropos "LISS" as the headline of today's On Short Notice news quickie already gave away, light intensity steady state aerobic training aka LISS is one of the exercise related topics today. We will however start out with the health related news... and don't wonder that the first post is about polar bear health. I promise you will be intrigued, when you've read it ;-)

• 'Westernized' polar bears' bones look as if they would need vitamin D supplements, in reality all they are probably missing is sufficient taurine in their diet. I don't know but maybe you've asked yourself before: "How on earth can a white bear survive in the Arctic, when his nose is the only part of his skin that's exposed to the sun and would thus be able to produce vitamin?" (Please mind that this is not a serious question ;-) He eats his vitamin D!
  
  

  

  Scientists speculate: Their cousins in captivity suffer from rickets and fractures due to secondary vitamin D deficiency in consequence of insufficient taurine intake.

  Ok, first question first answer, but what about question #2: "How come that the clubs of his brethren and cousins in captivity get rickets and fractures as if they were vitamin D deficient, although they get the exact same amount of vitamin D from mother's milk and their later diet (sometimes the latter is even supplemented) as their wild counterparts?" Answer? No idea? Well, if you ask the researchers from the The University of Tennessee Health Science Center the answer is (Cheesney. 2009): A lack of taurine in the diet.
  
  Taurine plays a fundamentally important role in the conjugation of ursodeoxycholic acid to TUDCA and facilitates the uptake of fatty acids and fat soluble vitamins. With insufficient taurine in the diet polar beers (and human beings) can probably drink as much vitamin D in olive oil or whatever other fat base they deem more appropriate then dry tabs without any effects on their 25-OHD => calcitonin levels and consequently bone health (suggested read "Fat D-Ficiency! Study Shows, Even 50.000 IU of Vitamin D3 Useless, When You Ingest It Without Fat").
  
  Moreover, a recent guinea pig study from Department of Internal Medicine at the Medical College of the National Cheng Kung University suggests that glycine could be another 'pro vitamin D amino acid' due to its beneficial effect on the liver and subsequent protection of disturbances in vitamin D metabolism and low 25-OHD levels (Chen. 2008) - now, what if any of these, i.e. taurine or glycine, or simply insufficient bile acid, which incidentally depends on the consumption of the "bad, bad" cholesterol (cf. Kern. 1994), is the actual reason of the rampant vitamin D deficiency in our meat-, fat- and cholesterol-o-phobic societies?
• "Low vitamin D and remote EBV infection may be associated with clinical MS breakthrough within 2-3 years." (Décard. 2012) Usually I don't simply copy the study titles, but this one says it all. Even before the first symptoms of multiple sclerosis occur, i.e. in the so-called pre-CIS (=clinically isolated syndrome) interval, patients with quiescent multiple sclerosis have 50% lower 25OHD levels than their healthy peers and - what could actually be the causal factor, here - three times higher Epstein-Barr specific IgG levels (EBNA1). Can these observations a group of scientists from the Department of Neurology at the St. Josef-Hospital of the Ruhr-University Bochum in Bochum, German, really be mere coincidence?
  
  

  

  Figure 1: While it would be best never to be infected with Epstein-Barr your risk of EP-related MS is more than twice as high if you are exposed late (Ascherio. 2010)

  At least as far as the Epstein-Barr relation goes the answer of a 2010 review of the literature would be 'no, probably no coincidence' (Ascherio. 2010). It appears to be established that Epstein-Barr (EB) plays a pivotal role in the etiology of MS. Based on the observation that people without EB are virtually MS free, and the fact that their own previous research has clearly shown that late infections with EP increase your risk to develop MS by more than 2x (compared to people who have been exposed in childhood; see figure 1), Ascherio et al. argue that it is very unlikely that EP is not at least the trigger, if not the ultimate cause of MS.
  
  The scientists also refer to the hygiene hypothesis which has been advanced by other authors before, unfortunately, however, getting rid of the 'cleanliness' and exposing your immune system to the training it needs by exposing yourself to the virus at an earlier age, is of little use, if not totally stupid. After all it would only reduce your risk to develop MS to a level that's still more than 1,000% higher than in people who have never been exposed to the virus in the first place (see figure 1).
  
  Due to the inconclusive data on the long and short term effects of Epstein-Barr infections on the B-cell and T lymphocyte response, the Ascherio et al. are not yet sure about the exact mechanism by which EP stimulates, triggers or drives the development of MS. All that can be said with relative certainty is that Epstein-Bar infections contribute to the increase in multiple sclerosis. Aside from the previously mentioned correlations the mere fact that those regions of the world where Epstein-Barr is quasi non-existent are virtually MS free is probably the best evidence of its involvement in autoimmune attacks on your brain. So if you want to protect yourself you better make sure you don't get infected!  Since EP is part of the herpes family and transmitted via saliva this is unfortunately not exactly easy...

• 

  Figure 2: Overall there is no statistical significant downside to chronic paracetamol supplementation, but there is a slight advantage for the NSAID free group in term of increases in lower body strength - the time course (not shown) of the strength gains was by the way identical for both groups, as well (Jankowski. 2012)

  Paracetamol does not interfere with muscle gains in elderly men. The issue whether or not NSAIDs will interfere with resistance training induced gains in skeletal muscle is certainly relevant for everyone. If there is one group of people for whom it could be of paramount importance, though, this would be the men and women in their best ages (>50 years) who have finally realized that muscle is not just metabolic currency, but a true life insurance.
  
  Against that background the most recent results from the College of Nursing at the University of Colorado Anschutz Medical Campus may be important news (Jankowski. 2012). I mean, if the use of N-acetyl-4-amniphenol (ACET) aka paracetamol would hamper or even forestall muscle gains, the training efforts of the men and women who take ACET would be to no avail.
  
  Now the good news is that the chronic use of paracetamol at a daily dose of 1,000mg did not reduce the lean mass gains in the 17 men (age >50y) who actually participated (instead of giving up) in all of the 3-5 days A/B resistance training sessions
  
  • workout A: R three sets of lateral pull down, bench ress, hip abduction and adduction, biceps curls, seated row, and ssisted chin ups
  • workout B: overhead press, leg press, triceps xtension, knee extension and flexion, heel raise, and shoulder external rotation
  • warm up / cool down: 10 min warm-up on the treadmill, a stair climing intermezzo after the first warm up sets and another 10 min cool down
  that were performed with at 80% of the 1-RM and with at least 1 day off in-between over a period of 16 weeks.
  
  
  The chronic ingestion of paracetamol is not advisable regardless of its negligible detrimental effects on skeletal muscle gain. Only recently, Kane et al. have shown that older people in are particularly prone to the hepatoxic effects of this (imho falsely OTC available) NSAID (Kane. 2012). If there is no way around it, because you cannot stand the pain, a safer (at least for the liver) and more effective medical approach could be the combination of tramadol (75 mg), a weak opioid analgesic, with low dose of paracetamol (325-650mg, max!; cf. Pergollizzi. 2012).
  In as much as the nonexistent negative effects are good news, they are likewise strange news, because according to the expression of proteins involved in the protein synthetic response to exercise, it should actually have hampered the gains:
  

  "[...] in the ACET group that the expressions of the anabolic gene p70S6K and the catabolic gene MAFbx were significantly reduced at week 16 of PRT. Given that the increases in FFM in response to PRT were not significantly different between the groups, it is possible that the suppression of catabolic signaling was sufficient to offset reductions in anabolic signaling in the ACET group." (Jankowski. 2012)

  As the authors point out future studies will have to elucidate the exact mechanism this at first sight contradictory results.
  
  In the mean time Jankowski et al. do yet speculate that the loss of prostaglandin signalling and supsequent increases in p70S6K, the protein that's responsible for muscle protein synthesis may be countered by the normalizing effects paracetamol exerts on the expression of Akt, the ameliorative effect on the overexpression of nitric oxide synthase (iNOS) and the reduction of the age-relatedly increased myocyte apoptosis.
  

• 

  Compared to Hope Solo or Serena Williams Olympian Brian Lochte, is probably a weakling - of course only as far as the fatigabilty of his skeletal muscle is concerned - as far as the risk do develop the Athlete's Triad is concerned, this may yet be advantage.

  Men and women tire differently - men (once more ;-) the weaker sex Let's face it guys,  we are weaklings. At least this is what Beth W. Glace and her colleagues from the Nicholas Institute of Sports Medicine and Athletic Trauma at the Lenox Hill Hospital in New York report in their latest paper. Other than the quadriceps muscles of our significant others, our muscles fatigue after 2h of cycling with intermittent one minute sprints every 20 minutes.
  
  In women, in this particular case just like their male counterparts trained cyclists or triathletes with a training load of at least 100km per week, on the other hand, it's solely the central nervous system fatigue that will keep them from cycling 'forever'. Unfair, right? Us men have to battle both, central as well as local muscular (=peripheral) fatigue.
  
  Now what seems nothing but advantageous can however turn against you. In a way the low fatigability of female muscle is also part of the reason why are way more susceptible to the athlete's triad (click here to learn more) than men: They are simply able to work their CNS into the ground, because their peripheral musculature is less prone to exhaustion.
• Recent study puts question mark behind assumed appetite reducing benefit of HIIT sprints vs. classic aerobics - but does that mean that aerobics is the way to go? Not yet in press, but already intriguing are the results of a recent study by  Kevin Deighton et al. from the School of Sport at the Loughborough University who say that they found that ...
  

  "[a]n acute bout of endurance exercise resulted in lower appetite perceptions in the hours after exercise than sprint interval exercise and induced a greater 24 h energy deficit due to higher energy expenditure during exercise" (Deighton. 2012)

  

  Figure 3: Intentionally or not, based on the conclusion of the abstract you would probably not have expected to see these results (data adapted from Deighton. 2012)

  Now this sentence from the abstract certainly suggests that sprinting would have nothing but negative effects. The actual data you see in figure 3 does yet tell you something different. The sprinters may have had increased ghrelin and lower PYY levels with the expected downstream effects on perceived hunger, but this did not translate into significant differences in food intake. In other words, even longish sprint exercises like the ones in the study at hand won't put you at danger of overeating - despite transient increases in ghrelin levels.
  
  In fact, the increased ghrelin amplitude can actually be an advantage (see August 04, 2012) and the calories in vs. out calculation the scientists do is so irrelevant to the real world health and body composition effects of exercise that I refuse to repeat it here ("No, you cannot eat that extra piece of layer cake because you ran on the treadmill earlier today" ;-)
  
  In the end, comparisons like this always suggest you had to choose between doing one or another mode of "cardio", when a combination of both, i.e. cycling HIIT and LISS, yet not both in one session, would be the most productive way to go. And no, Mr. Taubes, none of them is "just going to make you hungry" (see "Every Dog Has His Day: Dr. Oz Was Right, Exercise Does Not "Just Make You Hungry", But Reduces Energy Intake!")
  
• Researchers debate the "low vs. high weight" conundrum. In the editorial to the next issue of the Journal of Applied Physiology Mark D. Schuenke, Jennifer Herman, and Robert S. Staron reject the criticism they received from Nicolas Burd et al. for the pro heavy weights arguments they put forward in their recently published study on the effects of high vs. low weight training (Schuenke. 2012a; covered on the SuppVersity on October 01, 2012). Now while this back and forth between the two groups does not deliver any new data, I believe that it is still interesting and highly educative to see how science is actually a matter of negotiated not set truths. So, let's see how Schuenke et al. respond to Burd's assertion that ...
  

  

  Figure 4: Changes in body composition (left) and changes in muscle fiber cross-sectional area in response do different training regimen (Schuenke. 2012a; this study was discussed here on the SuppVersity on October 01, 2012)

  "[t]he authors’ views continue to contribute to a resistance training doctrine that is incorrect, most notably the belief that heavier weights are better concept. This conclusion is likely due to the relative dearth of quality studies assessing the hypertrophy potential of lower load resistance training paradigms, in contrast to the large number of studies employing ‘traditional’ resistance training intensities (*70 % of maximal strength).

  Clearly, evidence exists to support the concept that light(er) loads can support training-induced muscle hypertrophy both independently and by comparison to heavy loads. We would propose that so long as the stimulus is an overload, performed with high effort (fatigue), and progressive then even the most seasoned lifters would see progression,  at the very least no regression, in strength or muscle mass." (Burd. 2012)

  I will briefly summarize the most important points the researchers from the University of New England College of Osteopathic bring forward to defend their "go heavy or go home" argumentation:
  
  • The list of previous studies which confirm the the efficacy of training with high(er) weight for "optimal" gains in hypertrophy and strength is extensive.
  • Low load training is not as Burd et al. suggest "simply a milder form of low-load blood flow restrictive exercise", of which the researchers state that it is "interesting".
  • Schuenke et al. specifically refer to a Y2k study by Takadara et al. which shows that without the cuffs light loads don't build anything (Takadara. 2000).
  • The researchers point out that the claim by Burd et al. that "maximal muscle fiber activation can be achieved in any circumstance as long as the effort is to failure is unwarranted and unsubstantiated".
  • The study by Mitchel et al. Bird et al. cite to prove their hypothesis may not report significant differences between knee extensions performed at 30 % of 1RM for 3 sets, 80 % of 1RM for 1 set, or 80 % of 1RM for 3 sets as far as the isometric strength and hypertrophy between the three types of training are concerned, but
    

    "[t]his result is not surprising considering the following: (1) no control group was used, (2) each subject trained each limb using a different protocol (cross-over effect), (3) only one single-joint exercise was used (low volume versus a much higher volume of training used, for example, in Schuenke et al.: 3 sets each of leg press, squat, and knee extension), and (4) only fiber types I and II were delineated (severely limiting interpretation of the results).

    In that the last parentheses is obviously another direct criticism of what Schuenke would probably call "cherry picking" studies and specific results to support an unwarranted hypothesis.
  Based on this line of argumentation, Schuenke et al. conclude their deliberations on the note:
  

  

  One should not forget that it's not only about light vs. heavy, but in as much about appropriate and inappropriate weights. If you go by the quantity of the evidence there is however no debating that those weights are too light - probably even for a Lady in her best years.

  "Low-load training appears to have some merit. How-ever, our data support the use of high-load, high-intensity resistance training to maximize fiber hypertrophy and strength. In addition, heavy loading of the muscle has an impact on bone and other connective tissues which are minimized/lacking using low-load training. Finally, Burd et al. appear to oversimplify the field of exercise physiol-ogy. To claim that any training load (light or heavy) con-fers the same physiological adaptations as long as the end point is volitional failure is shortsighted and similar to claiming that running for any distance or time will elicit the same effects as long as fatigue is reached." (Schuenke. 2012)

  If you asked me, both are right. While I personally tend to agree with Schuenke, the main reason that I do is that the heavy weights approach is tried and proven, while - just as Burd says - the sceintific evidence pertaining to low weights is scarce and ambiguous and the anecdotal evidence from 'big guys' is non-existent. I am still curious about the next move(s) on both sides of this divide. And by the way, conflicts like these have always been among the driving forces of scientific progress, so I am pretty sure that we as trainees can only benefit from this debate as well as potential follow-up studies, both groups will feel inclined to conduct in order to 'prove' their point.

That's all for today! I hope you enjoyed the stay, all have electricity and an intact water supply ... I mean it's nice if you have a fully charged iPhone to get your daily dose of SuppVersity news, but even I have to concede that some other things in live are way more elementary.

References

• Ascherio A, Munger KL. Epstein-barr virus infection and multiple sclerosis: a review. J Neuroimmune Pharmacol. 2010 Sep;5(3):271-7.
• Burd NA, Moore DR, Mitchell CJ, Phillips SM. Big claims for big weights but with little evidence. Eur J Appl Physiol. 2012 Oct 20. 
• CDC. Early Release of Selected Estimates Based on Data From the January–March 2012 National Health Interview Survey. September 2012
• Chen CY, Wang BT, Wu ZC, Yu WT, Lin PJ, Tsai WL, Shiesh SC. Glycine ameliorates liver injury and vitamin D deficiency induced by bile duct ligation. Clin Chim Acta. 2012 Oct 23-
• Chesney RW, Hedberg GE, Rogers QR, Dierenfeld ES, Hollis BE, Derocher A, Andersen M. Does taurine deficiency cause metabolic bone disease and rickets in polar bear cubs raised in captivity? Adv Exp Med Biol. 2009;643:325-31.
• Deighton K, Barry R, Connon CE, Stensel DJ. Appetite, gut hormone and energy intake responses to low volume sprint interval and traditional endurance exercise. Eur J Appl Physiol. 2012 Oct 31.
• Décard BF, von Ahsen N, Grunwald T, Streit F, Stroet A, Niggemeier P, Schottstedt V, Riggert J, Gold R, Chan A. Low vitamin D and elevated immunoreactivity against Epstein-Barr virus before first clinical manifestation of multiple sclerosis. J Neurol Neurosurg Psychiatry. 2012 Aug 11.
• Kane A, Mitchell SJ, Carroll PR, Matthews S, Hilmer SN. Characteristics of older and younger patients with suspected paracetamol toxicity. Australas J Ageing. 2012 Sep;31(3):190-3.
• Kern F Jr. Effects of dietary cholesterol on cholesterol and bile acid homeostasis in patients with cholesterol gallstones. J Clin Invest. 1994 Mar;93(3):1186-94.
• Kappenstein O, Vieth B, Luch A, Pfaff K. Toxicologically relevant phthalates in food. EXS. 2012;101:87-106.
• Pergolizzi JV Jr, van de Laar M, Langford R, Mellinghoff HU, Merchante IM, Nalamachu S, O'Brien J, Perrot S, Raffa RB. Tramadol/paracetamol fixed-dose combination in the treatment of moderate to severe pain. J Pain Res. 2012;5:327-46.
• Schuenke MD, Herman JR, Gliders RM, Hagerman FC, Hikida RS, Rana SR, Ragg KE, Staron RS. Early-phase muscular adaptations in response to slow-speed versus traditional resistance-training regimens. Eur J Appl Physiol. 2012a Oct;112(10):3585-95.
• Schuenke MD, Herman J, Staron RS. Preponderance of evidence proves "big" weights optimize hypertrophic and strength adaptations. Eur J Appl Physiol. 2012b Oct 25.
• Sioen I, Fierens T, Van Holderbeke M, Geerts L, Bellemans M, De Maeyer M, Servaes K, Vanermen G, Boon PE, De Henauw S. Phthalates dietary exposure and food sources for Belgian preschool children and adults. Environ Int. 2012 Nov 1;48:102-8.
• Takarada Y, Takazawa H, Sato Y, Takebayashi S, Tanaka Y, Ishii N. Effects of resistance exercise combined with moderate vascular occlusion on muscular function in humans. J Appl Physiol. 2000; 88:2097–2106.

Vitamin D Supplementation(!) Increases Testosterone in Men

Thanks to Dashforce from the MindAndMuscle-Forum we finally have evidence for the direct effect of vitamin D3 supplementation on testosterone in men. Dashforce reports on a study by scientists from Austria and Germany (Pilz. 2010) who provided 54 men, whose serum levels were previously at the lower range ~30ng/ml (the referential  minimum varies depending on which source you cite from 30-50ng/ml),with either 83 μg (3 332 IU) vitamin D daily or placebo for 1 year.

Table 1: Characteristics of the study groups at baseline and at the end of the study

As you can see in table 1,vitamin D supplementation lead to a significant increase in total testosterone from 10.7 nmol/l to 13.4 nmol/l. What's even more important, this increase (+25%) was not compensated by and an increase of SHGB, so that the amount of free testosterone rose from 0.222 n/mol to 0.267 nmol/l, i.e. by +20% (vs. +5% in the placebo group).

What is particularly interesting about this study is the fact that supplementation actually raised the level of testosterone. This is different from most previous studies, which observed a correlation between higher vitamin D levels and higher testosterone levels. If for example some probands would simply have been more healthy and thus exhibit higher levels of both, we would have had the same correlation. In the case of the Pilz study there is a clear causative effect between restauration of adequate vitamin D levels and increases in total and free testosterone.

I hope we see more trials with a similar design - also to investigate if there is a dose response relationship and whether even higher vitamin D levels would further increase testosterone. Until then, keep an eye on your vitamin D level and take a supplement to get to the upper ranges of the "normal" range ~80ng/ml.

Vitamin D Levels Associated with Adipose Fat Mass

Today is the day for our weekly news on vitamin D (never hard to find some ;-) Sciencists from Atlanta (Lin. 2010) recently found that the dramatic weight loss patients experience after roux-en-y gastric bypass (RYGB) surgery goes hand in hand with an initial increase in plasma 25(OH)D concentration:

Strong positive baseline and 1 month cross-sectional correlations between FAT and plasma 25(OH)D were observed, which remained after adjustment for age and race subgroup (β = 0.76 and 0.61, respectively, P = 0.02)

Interestingly, this intermittent increase was followed by a decreasing trend over the rest of the 24 month study period, so that

Despite temporary improvement in vitamin D status, a high prevalence of vitamin D insufficiency was observed (76, 71, 67, and 82%, at baseline, 1, 6, and 24 months, respectively), and plasma 25(OH)D concentrations were lower in AA compared to white patients (P < 0.05).

The scientists conclude that in the course of the dramatic weight loss of the first weeks after surgery stored vitamin D was released from the fat cells and thus contributed to the temporary increase in vitamin D levels. This, however, was not enough to restore 25(OH)D levels, which tend to be depressed in obese individuals, anyway, to the normal range. Supplementation may thus be warranted.

Vitamin D Does not Improve Muscle Strength

In view of all the hype surrounding vitamin D, I think it is my duty to report on "negative" or inconclusive results of the ongoing research of the effects what some call a vitamin, others a hormone. Stockton et al. (Stockton. 2010) have now published a systematic review of the effect of vitamin D on muscle strength. After evaluating data from 52 studies, involving 5,072 participants, their conclusion is quite unambiguous:

Based on studies included in this systematic review, vitamin D supplementation does not have a significant effect on muscle strength in adults with baseline 25(OH)D >25 nmol/L. However, a limited number of studies demonstrate an increase in proximal muscle strength in adults with vitamin D deficiency.

Bottom line: Go see a doctor, have your vitamin D levels checked and if you are deficient (if you are living in the Nothern Hemisphere, chances are that your levels are too low especially in the winter month), supplement with an adequate amount of vitamin D.

Vitamin D Deficiency Impairs Learning

They keep coming, and I keep repeating myself: vitamin D is the most interesting "novel" supplement out there. A recent study Mohsen et al. (Mohsen. 2010) found that vitamin D deficiency, apart from increasing risk of fractures and metabolic diseases, also impairs learning. Investigating the learning process of water maze the scientists found:

The C-D [vitamin D deficient] group needed a longer time to reach the platform than the control and C+D [vitamin D repleted] animals (P<0.0001), demonstrating that vitamin D deficiency negatively affected the maze learning. On the other hand, calcitriol supplementation did not significantly influence the spatial learning.

In view of these facts: If you do not notice that I posted the following only a few days ago,

 "So, do your heart, your pancreas and, not to forget, your bones a favor and grab some vitamin D supplements." (Vitamin D: 1 Billion People Worldwide Are Vitamin D Deficient or Insufficient)

you either did not read it or you are so deficient in vitamin D that you just cannot remember ;-)