The project follows on from previous efforts to identify beneficial types of fat, also called lipids, which could be of interest for treating dementia. "In an earlier project called LipiDiet— (by contrast to the current) LipiDiDiet project—hundreds of lipids were screened to find out whether they could be beneficial," says Tobias Hartmann, a professor of experimental neurology at the Saarland University in Homburg, Germany, who is also the LipiDiDiet project coordinator.
The previous project identified several so-called 'bad' lipids, which had a negative effect, and a few which had just the opposite effect. "The best one from a practical point of view, [which] had to be digestible and non-toxic in amounts high enough to be effective, was an omega-3 fatty acid, [called] DHA, more commonly known as the active ingredient of fish oil," Hartmann tells CommNet.
But there is no consensus on whether DHA has a beneficial effect on the development of Alzheimer's disease. "In my research, I haven't seen any effect," says Ondine van de Rest, a researcher at the division for human nutrition from Wageningen University and Research Centre, in the Netherlands. Her PhD thesis focused on the effect of high dose fish oil supplementation on cognitive performance in patients with mild cognitive impairment. Her research is not the only one that casts a doubt over the protective properties of fish oil. A large intervention study by US scientists came up with the same findings.