The study, which is published online in the journal Neurology, is one of the first to investigate a range of nutrients in people’s blood, instead of using questionnaires to assess people’s diets. The researchers believe this method gives a more accurate picture of a person’s food intake, because it does not rely on people’s memory or honesty when answering questions about their diet.
Researchers at the Oregon Health & Science University, in Portland, studied blood samples from 104 healthy older people with an average age of 87, who had few known risk factors for Alzheimer’s. They categorised the participants into eight groups according to the profile of nutrients contained in their blood, and analysed how people in each group performed in a series of cognitive tests.
They found those whose blood contained more vitamin B, C, D and E were the best performers in cognitive tests, while people with higher levels of omega 3 fatty acids also had high scores in these tests. Vitamins B, C and E are mainly found in fruits and vegetables, while vitamin D and omega 3 fatty acids are mainly contained in fish.
Conversely, people whose blood had higher levels of trans fats – found mainly in cakes and fried foods – had the worst cognitive scores.
The researchers also analysed MRI scans from 42 of the participants, and found that those whose blood had higher levels of vitamins and omega 3 were also more likely to have bigger total brain volume. In comparison, those with more trans fats in their blood had less brain volume.
Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, said:
“One strength of this research is that it looked at nutrients in people’s blood, rather than relying on answers to a questionnaire. It’s important to note that this study looked at a small group of people with few risk factors for Alzheimer’s disease, and did not investigate whether they went on to develop Alzheimer’s at a later stage. There is a clear need for conclusive evidence about the effect of diet on our risk of Alzheimer’s, which can only come from large-scale, long-term studies.
“Although there is no sure-fire way of preventing Alzheimer’s yet, we know that risk factors for heart disease and stroke can also increase the risk of dementia. The best advice at the moment is to eat a balanced diet with plenty of fruit and vegetables, and keep healthy by not smoking, taking regular exercise and keeping blood pressure and cholesterol in check.
“Currently 820,000 people are affected by dementia in the UK and with a rapidly ageing population, those numbers are expected to soar. We urgently need to find ways to prevent dementia if we are to head off a future crisis, and that means it’s vital to invest in research.”
Alzheimer’s Research UK
The Stables, Station Road, Great Shelford, Cambridge, CB22 5LR
Registered charity number 1077089 and SC042474.