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Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "
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27.10.2010 |
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The joint anabolic effect of EPA and HMB
The omega-3 fatty acid EPA enhances the mild anticatabolic effect of the leucine metabolite HMB [structural formula below]. Pharmacologists at Aston University came to this conclusion after doing an animal study, published in Cancer Research in 2005.
Leucine oxidises more easily than other amino acids. That’s probably why muscle cells have developed anticatabolic mechanisms that are activated immediately when the cell detects leucine conversion products. Exactly which metabolites these are is not yet clear, but betahydroxy-methylbutyric acid, HMB for short, is one of them. The researchers who launched HMB on the market at the end of the nineties had high expectations of the substance, but studies have lowered these. HMB inhibits protein metabolism in muscle cells, which means it does the same to the processes of protein breakdown.
Omega-3 fatty acids inhibit muscle breakdown too. Some trials show that weakened cancer patients who are given protein shakes containing EPA even build up a little lean body mass.
So what happens if you combine EPA and HMB? Might this protect cancer patients against undesired weight loss? This is the question the researchers set out to answer in a 12-day experiment. They introduced cancer cells into mice and gave them HMB after 9 days.
The higher the dose, the greater the effect of the leucine metabolite on the lab animals’ gastrocnemius [calf muscle].
The figure below shows that high daily doses of over 0.125 g/kg bodyweight had no extra effect. The black bars represent muscle protein production, the white ones muscle breakdown. HMB is primarily an anticatabolic.
HMB and EPA together worked better than each substance separately, as the figure above shows. It shows the weight of the gastrocnemius after 3 days of being given the supplement.
So EPA and HMB do not work synergistically, but their anticatabolic effects are cumulative, in the researchers’ view.
The researchers worked out how the anticatabolic effect of HMB and EPA works. The compounds inhibit the proteasome in the muscle cells. The graph below shows the extent to which they do this. The proteasome is a kind of cellular demolition workshop, where the enzyme chymotrypsin cuts up proteins into little pieces.
"HMB may be safely used either alone or in combination with EPA to treat muscle atrophy in cancer cachexia and acquired immunodeficiency syndrome", the researchers conclude. Their work was financed by Abbott Laboratories, the owner of the EAS supplement brand. EAS made good money from HMB for years, although sales are now on the decline.
We’re not such believers in HMB. As long as we don’t know exactly which leucine metabolites are the most effective muscle-growth stimulators, we are placing our bets on high doses of leucine. This study indicates that it’s likely that leucine is more effective when combined with omega-3 oils.
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