you’re an astute reader of my blog then you’ll notice that, apart from blogging about how to drink wine without killing your brain cells, I’ve steered clear of writing about diet and brain health. Mostly because I’ve not been convinced that the evidence was particularly strong enough, and there is just SO MUCH content online about healthy eating and I’ve been reluctant to add to the noise.
What diet is best for your brain?
Vegetarian, no-sugar, vegan, paleo, low-GI, dairy-free, high-protein, lacto-ovo, green juice, lemon juice in warm water …. the list of diets and diet gurus claiming to have THE answer to whatever ails you is endless and confusing. However, it is worth nothing there are one or two key things that most sensible diets have in common – they rely on unprocessed whole foods, and they cut out the junk. Simple! Nothing wrong with that at all.
Recently, a new systematic review has come to my attention, and I therefore thought it was about time I wrote about…
The link between diet and brain health
I like systematic reviews — they are generally the strongest form of medical evidence there is as they pool together the data from numerous studies, and don’t rely on one research group’s conclusions or spin on the data.
For this review (published in July 2013 in the Epidemiology journal), scientists lead by Dr David Llewellyn from the University of Exeter Medical School pooled data from 12 scientifically sound papers (including one clinical trial). Seven studies from the United States, three in Australia, and one each in the Mediterranean countries of France and Greece.
This is the first systematic review of the evidence confirming that …
The Mediterranean diet slows cognitive decline and reduces the risk of developing Alzheimer’s disease.
This finding is in line with other systematic reviews showing the Mediterranean diet protects against cardiovascular diseases, cancer, and overall mortality (that is, your chance of dying).
The Mediterranean diet plan …
- extra-virgin olive oil as the main source of dietary fat
- lots of fruits, nuts, vegetables and pulses
- lots of fish and seafood
- some dairy products and red meat
- moderate intake of red wine (hooray!)
Another ‘gold standard’ of medical research is the randomised clinical trial. And one such trial is currently underway in Spain…
The PREDIMED study – has divided its 7,447 older subjects at high cardiovascular risk into two groups. One group is following the recommendations of the ‘low-fat’ diet ‘traditionally’ recommended as best for heart health. They eat low-fat dairy, bread, pasta, potatoes, fish, fruit and vegetables. They are being compared to the Mediterranean diet group who consume 4 tablespoons of olive oil daily, plenty of nuts, fruit and vegetables, and wine with meals. Both groups are discouraged from eating red and processed meat.
Cognitive testing of 522 particpants from PREDIMED has shown that…
A Mediterranean diet enhanced with either extra-virgin olive oil or nuts appears to improve cognition compared with a low-fat diet.
Results showed that after participants in the Mediterranean diet group had small improvements in two measure of cognitive function, the Mini-Mental State Examination (MMSE) and Clock Drawing Test (CDT), compared with the control low-fat diet.
Or in other words, the Mediterranean diet seems to boost ageing brain power AND is better than low fat option for those at risk of vascular dementia.
How does the Mediterranean diet keep the brain healthy?
One suggestion is that the Mediterranean diet works via the heart – heart health and brain health are very tightly linked.
Dr Martinez-Gonzalez, a PREDIMED trail scientist says,
This is thought to be mediated by an anti-inflammatory vascular effect. The better cognitive function could be a direct result of the cardiovascular benefit — a consequence of better vascular function.
Another mechanism the Mediterranean diet works is via prevention of oxidative stress, as outlined by Cinta Valls-Pedret and Emilio Ros in a comment in the Epidemiology.
For many age-related diseases, oxidative stress leads to chronic inflammation and in the brain this plays a major role in neuro-degeneration (death of brain cells), cognitive decline, and dementia.
For this reason, anti-oxidants and improved nutrition are potential strategies to delay cognitive decline and prevent progression to Alzheimer’s disease. Antioxidants, which are integral components of vegetables, prevent oxidative stress. Some examples of antioxidants include: fatty acids, B-vitamins, and antioxidant nutrients such as vitamins E and C, carotenoids, and flavonoids, a subtype of polyphenols.
Antioxidants! Surely just taking antioxidant supplements should simple and easy way to improve brain health …. right?
Clinical trials of anti-oxidant supplements have failed to show any clear benefit to health. And in some cases, antioxidant supplements have been shown to increase death rates ( here is a link to the research). Quite simply, the current evidence does not support the use of antioxidant supplements in the general population or in patients with various diseases.
No. Instead you have to EAT WHOLE FOOD – that being … extra-virgin olive oil, lots of fruits, nuts, vegetables and pulses, lots of fish and seafood, some dairy products and red meat, and moderate amounts of red wine.
The “single nutrient” approach fails. The “whole diet” approach does not!
I agree with another epidemiologist writing in the edition of Epidemiology, Rachel Whitmer an epidemiologist, says,
…the pleasures of Mediterranean cuisine can have salutary health effects—and that, with delayed cognitive decline and decreased risk of Alzheimer’s disease, we may be able to savour and enjoy these pleasures well into our older age.
So, your simple, actionable step to better brain health to take from this research?
Eat a Mediterranean diet to slow your cognitive decline and reduce your risk of developing Alzheimer’s disease.
Leave me a comment below. Do you eat a Mediterranean diet? Do you see this as a simple step to take to improve brain health, or is it in your ‘too hard’ basket?
Lourida et al. 2013. Mediterranean Diet, Cognitive Function, and Dementia: A Systematic Review. Epidemiology, 24(4):479-489. Martínez-Lapiscina 2013 Mediterranean diet improves cognition: the PREDIMED-NAVARRA randomised trial.J Neurol Neurosurg Psychiatry. Tsivgoulis et al Adherence to a Mediterranean diet and risk of incident cognitive impairment. Neurology, 2013; 80 (18): 1684. Valls-Pedret & Ros 2013. Mediterranean Diet and Cognitive Outcomes Epidemiological Evidence Suggestive, Randomized Trials Needed Epidemiology, 24( 4):505.
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About Dr Sarah
I’m an Oxford University-educated neuroscientist, presenter of ABC Catalyst, director of The Neuroscience Academy, and author of The Women's Brain Book. The neuroscience of health, hormones and happiness.
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[…] blogged about a few weeks back that scientists are pretty confident that the Mediterranean diet appears to offer protection […]
[…] How should polyphenols be taken? Naturally as a fruit, processed into juices, extracts and tablets, or given as individual polyphenols? At present, there is not much evidence about which form is the best to administer. Personally, I’d stick with the whole food (and I talk about why here). […]
virgin olive oil is very helpful for our health but it is very cheap and poor food. there are no man they can not like virgin olive oil.
According to this study there are other contributing factors to the apparently positive effects of a “Mediterranean diet”
Love this! Thank you for sharing!