Science - April 15, 2010

The heart keeps its own fat levels down

Protein inhibits fat absorption by heart muscle cells. Mechanism probably works in humans too.

Arteries on a human heart
The heart is capable of protecting itself against too much fat in the diet. Mice that were given a snack full of fat activated a protein that reduces the uptake of fat by heart muscle cells. These are the findings of a study that Sander Kersten, professor at the Human Nutrition department, published last week in Circulation Research. 'We have recently acquired the tool that enables us to find out the protein's function', says Kersten. That tool took the form of knockout mice that were unable to synthesize this protein. They absorbed significantly more fat into the heart muscle cells after a meal with large amounts of oil.

Taking the hit
Nutrigenomics play a key role in Kersten's heart research. This technique allows researchers to determine which genes are active after a meal, or indeed become less active. 'We looked at around 30 thousand genes in the hearts of normal mice and this was the one gene that became much more active after an oil-rich meal', says the researcher. 'This led to the production of the protein that inhibits fat absorption into the heart cells.' Limiting the amount of fat absorbed by the heart muscle prevents damage. The heart burns fat to produce energy, but fatty acids can also be converted into harmful oxidation products. 'The protein inhibits fat uptake in order to limit the number of radicals.'  

Excess
Does that mean we can enjoy regular fatty snacks after all? Kersten thinks that is not a good idea. 'The mechanism does not function so perfectly that it can completely offset an excess of fat', he says. 'It also looks as if the mechanism doesn't work as well with saturated fats.' And those are precisely the fats that are bad for your health.  'Although you can never be one hundred per cent sure, in vitro studies of human cells suggest it is highly likely that this mechanism functions in humans in the same way as in mice.'

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