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Extra vitamin D: more muscle, less fat

If you fatten rats using a high-fat or a high-sucrose diet, of course they'll get fatter. If you give them extra vitamin D and calcium in their food then something happens that bodybuilders might find quite interesting. The animals donít get fat so quickly but they do build up more muscles.

In the US, as in all other rich countries, the population is getting fatter and fatter. For this reason nutritionists at Purdue University are studying whether it's possible to do something about the problem by making simple changes in people's eating habits. And because some epidemiological studies claim that dairy consumption inhibits obesity, the researchers were curious to know whether their lab animals would get fatter less quickly if they were given extra vitamin D and calcium in their food.

The researchers fattened up rats in two ways: with food to which they added soya oil [high fat] and food to which they added sugar [high sucrose]. Half of the rats in each group got food containing a 'suboptimal' amount of calcium and vitamin D [LD]. One kg of food in the LD group contained 400 IE vitamin D and consisted of 0.25 percent calcium.

The other half of both groups got food containing 10,000 IE vitamin D [HD]. The HD group's food consisted of 1.5 percent calcium.

When vitamin D and calcium were added to the food, the animals started to eat more. But they didn't get fatter. In fact the researchers noticed that the HD rats became thinner in the 13 weeks that the experiment lasted. And a tiny bit more muscular.

Extra vitamin D: more muscle, less fat

On top of that, the vitamin D and the calcium made the HD rats burn more fat.

Extra vitamin D: more muscle, less fat

When they examined the rats' muscle cells the researchers discovered the mechanism they think is involved. The HD rats' cells made more of the molecular linking protein PGC-1-alpha. PGC-1-alpha works in combination with the fat sensor PPAR-gamma and steers the making of mitochondria. Put simply: the better PGC-1-alpha works, the more easily muscle cells burn fat.

Extra vitamin D: more muscle, less fat

In the rats in the high-fat group, the mix also increased the manufacture of insulin receptors.

Now the calcium intake in rich countries is already on the high side. So extra calcium won't help most strength athletes who are bulking to build a better body. When it comes to vitamin D it's a different story. It seems that vitamin D supplements can help power athletes to develop a better body composition. It's the vitamin D intake in the rich countries of the northern hemisphere that is too low.

Nutr Res. 2008 Nov; 28(11): 783-90.

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