Exhaustive Aerobic Exercise Increases Serum Calcium Levels and Dietary Requirements

You probably have heard of the fundamental importance of calcium as a structural component of bones. Yet, calcium is way more than the building block of our bone structure and the concrete the of the hopefully non-existent plaque in your arteries. It is also one of the major players in muscle contraction. Thus, it is not very surprising that a group of Iranian Scientists (Pourvaghar. 2011) found major effects of pro-longed (15min) high intensity aerobic exercise on serum calcium levels of 12 randomly selected student athletes (22.36y; 75kg @ 1.76m):

[…] the participants' mean of serum calcium concentration in the first stage and before Balke exhausting aerobic exercise was measured 98.38 ng/mic L. In the second stage, i.e. after the exhausting aerobic activity, it increased to 114.96 ng/mic L. Research results indicated that the difference in serum calcium concentration between the first and second stages is significant (P= 0.0001).

With the calcium that is appearing in the blood of the athletes being leeched from bones, organs to fulfill the increased calcium needs of active muscle tissue. Due to calcium “consumption” and urinary losses, the scientists speculate, the overall result to be a negative calcium balance.

Figure 1: Serum Calcium levels of athletes before, immediately after and 24h after exhaustive aerobic exercise. (Pourvaghar. 2011)

In view of the fact that, in the 24h after exercise, there is no sudden falloff (only -9.13%) of blood calcium, I would yet advice against extensive calcium supplementation. Previous works from other researchers have conclusively shown that a nutritionally dense, calorically adequate, diverse, calcium-rich diet satisfies the needs of both, the average gymrat and the hard training endurance athletes.

For athletes on a weight-reduction diet, or active gym-goers who – due to whatever other reasons – consume a diet that is low (<1.000mg/d) in calcium supplementing with a bio-available form of calcium, like calcium citrate, could yet be a viable strategy to prevent bone loss and sustain exercise performance.

Vitamin K for Healthy Bones & a Lean Physique: Rat Study Finds Phylloquinone (K1) & Menaquinone (K2) Ward off Fat Gain and Cut Triglycerides by Half

Until not too long ago, scientists thought vitamin D was all about bone. Every follower of this blog knows that this is a way too narrow perspective on what turned out to be more of a hormone than a vitamin. A recent study (Sogabe. 2011) on the effects of vitamin K supplementation in mice does now suggest that vitamin D's "cofactors" phylloquinone (PK, vitamin K1) and menaquinone-4 (MK-4, vitamin K2) have been similarly mistaken.

Figure 1: Weight of visceral fat pad in g after 85 days of  phylloquinone (PK, vitamin K1) or menaquinone-4 (MK-4, vitamin K2) supplementation (Sogabe. 2011)

Japanese scientists, who wanted to investigate the effect of 85 days of vitamin K supplementation (PK: 600 mg/kg; MK-4: 600 mg/kg) on bone development in mice, were surprised to find that vitamin K did not only improve bone mass and structure, but that...

the addition of PK or MK-4 significantly decreased the total fat accumulation (p < 0.01 and p < 0.05, respectively), and serum triglycerides were reduced by 48% in the PK group and 29% in the MK group compared with the control.

This is an interesting result, which is not related to increases in growth hormone release, as one might expect in view of the bone-building effects of vitamin K. The scientists speculate: "The effect of vitamin K on fat mass could be mediated through adiponectin regulation which itself has been found to be associated with fat mass." This, as well as the dose response relationship (the human equivalence dose for the amount of PK and MK-4 used in the study would be about 7.5g!) warrant further investigation - and, as always, the SuppVersity is the place to read about it, first!

High Protein Diet Safe for Bones! Acid Load due to Meat Protein does not Compromise Calcium Metabolism.

Reading the caption of this post, some of you may rightly ask themselves: "Why does he even mention this? Of course, meat is safe - meat is natural and eating meat is what man is made for!" So, if you already knew all that, you can stop reading now. If, however, you still belong to the misguided brotherhood of the followers of the holy food pyramid with your "healthy" grains, pasta and cereals at the bottom, you may be interested in the results from an older scientific paper I just came across while posting an answer to a forum post of someone who was concerned that his bones will become brittle if he increases his protein intake beyond the 0.8g/kg body weight barrier.

In November 2010, Cao & Nilsen (Cao. 2010) published a review which analyzed the outcome of studies that investigated the effect of the purported renal acid load resulting from a high protein intake (above the current Recommended Dietary Allowance of 0.8 g protein/kg body weight) on increased urinary calcium excretion. With reference to more recent findings they write:

Neither whole body calcium balance is, nor are bone status indicators, negatively affected by the increased acid load. Contrary to the supposed detrimental effect of protein, the majority of epidemiological studies have shown that long-term high-protein intake increases bone mineral density and reduces bone fracture incidence. The beneficial effects of protein such as increasing intestinal calcium absorption and circulating IGF-I whereas lowering serum parathyroid hormone sufficiently offset any negative effects of the acid load of protein on bone health.

By the way, I am already looking forward to the huge steaks I am going to have for lunch, today ;-)