The study will be published in the December issue of the Journal of Alzheimer's Disease and was directed by Mercedes Unzeta, professor of the UAB Department of Biochemistry and Molecular Biology. Participating in the study were researchers from this department and from the departments of Cell Biology, Physiology and Immunology, and of Psychiatry and Legal Medicine, all of which are affiliated centres of the Institute of Neuroscience of Universitat Autònoma de Barcelona. The company La Morella Nuts from Reus and the ACE Foundation of the Catalan Institute of Applied Neurosciences also collaborated in the study.
During the development of the brain, stem cells generate different neural cells (neurons, astrocytes and oligodendrocytes) which end up forming the adult brain. Until the 1960s it was thought that the amount of neurons in adult mammals decreased with age and that the body was not able to renew these cells. Now it is known that new neurons are formed in the adult brain. This generative capacity of the cells however is limited to two areas of the brain: the olfactory bulb and the hippocampus (area related to the memory and to cognitive processes). Although the rhythm of cell proliferation decreases with age and with neurodegenerative diseases, it is known that exercise and personal well being can combat this process.
The main objective of this research was to study the effect of an LMN cream-enriched diet on the neurogenesis of the brain of an adult mouse. Scientists used two groups of mice for the study. One group was given a normal diet and the other was given the same diet enriched with LMN cream. Both groups were fed during 40 days (approximately five years in humans). The analyses carried out in different brain regions demonstrated that those fed with LMN cream had a significantly higher amount of stem cells, as well as new differentiated cells, in the olfactory bulb and hippocampus.
The second objective was to verify if the LMN cream could prevent damage caused by oxidation or neural death in cell cultures. Cultures of the hippocampal and cortical cells were pretreated with LMN cream. After causing oxidative damage with hydrogen peroxide, which killed 40% of the cells, scientists observed that a pretreatment with LMN cream was capable of diminishing, and in some cases completely preventing, oxidative damage. The hippocampal and cortical cells were also damaged using amyloid beta (anomalous deposits of this protein are related to Alzheimer's disease). The results obtained were similar to those obtained using hydrogen peroxide.
These results demonstrate that an LMN diet is capable of inducing the generation of new cells in the adult brain, and of strengthening the neural networks which become affected with age and in neurogenerative processes such as Alzheimer's disease, as well as protecting neurons from oxidative and neural damage, two phenomena which occur at the origin of many diseases affecting the central nervous system.
In this study researchers have used different biochemical and molecular analysis techniques, with the help of specific antibodies, to detect different neuronal markers implied in the process of differentiation.
The group of researchers led by Dr Unzeta has spent years studying the effects oxidases have on oxidative stress as a factor implied in neurodegenerative disorders such as Parkinson and Alzheimer's disease, and the effects of different natural products with anti-inflammatory and antioxidant properties in different experimental models of Alzheimer's disease.
The study forms part of the CENIT project, which was awarded to La Morella Nuts in 2006 under the auspices of the INGENIO 2010 programme, with the objective of establishing methodologies for the design, evaluation and verification of functional foods which may protect against cardiovascular diseases and Alzheimer's disease. With 21.15m euros in funding and a duration of four years, the project has included the participation of 50 doctors and technicians from nine different companies, four universities (7 departments) and 2 research centres.
Over the past several decades, the food industry has reduced the amount of saturated fat in many products, and the public has reduced the amount of saturated fat in their diet. However, there has been a wide variation in the types of nutrients that have replaced this saturated fat. For example, in many products saturated fats were replaced with trans fats, which have since been determined to be detrimental; and in the overall American diet saturated fat was generally replaced with increased consumption of refined carbohydrates and grains.
“The specific replacement nutrient for saturated fat may be very important,” said lead author Dariush Mozaffarian, assistant professor in the department of epidemiology at HSPH and the department of medicine at Harvard Medical School. “Our findings suggest that polyunsaturated fats would be a preferred replacement for saturated fats for better heart health.”
Results from prior individual randomized controlled trials of saturated fat reduction and heart disease events were very mixed, with most showing no significant effects. Other trials focused only on blood cholesterol levels, which are an indirect marker of risk. Large observational studies have also generally shown no relationship between saturated fat consumption and risk of heart disease events; for example, earlier this month in the American Journal of Clinical Nutrition, researchers from HSPH and Children's Hospital Oakland Research Institute performed a pooled meta-analysis of prior observational studies and found no evidence that overall consumption of saturated fat was related to risk of coronary heart disease or stroke events.
Some of these mixed findings may relate to absence of prior focus on the specific replacement nutrient for saturated fat; in other words, was saturated fat replaced primarily with carbohydrate, monounsaturated fats such as in olive oil, or polyunsaturated fats such as in most vegetable oils?
Mozaffarian and his HSPH colleagues, Renata Micha and Sarah Wallace, performed a systematic review and meta-analysis of all randomized controlled trials through June 2009 in which participants specifically increased their polyunsaturated fat consumption as a replacement for saturated fat and in which coronary heart disease events were documented. Eight trials met the inclusion criteria, totaling 13,614 participants with 1,042 coronary heart disease events.
The meta-analysis of the trials showed that increasing polyunsaturated fat consumption as a replacement for saturated fat reduced the risk of coronary heart disease events by 19%. For every 5% increase (measured as total energy) in polyunsaturated fat consumption, coronary heart disease risk was reduced by 10%. This is now just the second dietary intervention–consuming long-chain omega-3 fatty acids is the first — to show a reduction in coronary heart disease events in randomized controlled trials.
Currently, the Institute of Medicine guidelines recommend that a range of 5%-10% energy consumption come from polyunsaturated fats. In addition, some scientists and organizations have recently suggested that consumption of polyunsaturated fats (largely “omega-6” fatty acids) should actually be reduced due to theoretical concerns that such consumption could increase coronary heart disease risk.
The results from this study suggest that polyunsaturated fats from vegetable oils may be an optimal replacement for saturated fats, an important finding for dietary guidelines and for when food manufacturers and restaurants are making decisions on how to reduce saturated fat in their products. The findings also suggest that an upper limit of 10% energy consumption from polyunsaturated fats may be too low, as the participants in these trials who reduced their risk were consuming about 15% energy from polyunsaturated fats.
Support for this study was provided by the National Heart, Lung, and Blood Institute, NIH and a Searle Scholar Award from the Searle Funds at the Chicago Community Trust.