Sharpening memory and cocoa - how interested should you be?

Farzaneh Sorond and colleagues from Harvard and the Mass. General Hospital have attracted worldwide interest in their study published in the US journal Neurology "Neurovascular coupling, cerebral white matter integrity, and response to cocoa in older people". 

Listen to interview on the story on BBC local radio
 
The theme of the interest - from the LA Times to the Belfast Telegraph - is that cocoa "not only soothes the soul, but might also sharpen the mind'.

Fruit of the theobroma cocoa tree: Corti et al. Circulation 2009 

Why even think that it might? The authors drew on two background concepts:
- Earlier research using sophisticated brain imaging had reported that cocoa intake is associated with an increase in blood flow to the brain; and brain blood flow is linked to intellectual capacity.
- And cocoa contains flavonols, bioactive chemicals present in many foods associated with measures of healthy cardiovascular health, including increasing blood flow to the gray matter of the brain.
The question asked by the researchers was whether previous interest in chocolate containing products and better brain function might be explained by flavonol effects. 
To address this they carried out a study in which the design was high quality with regard to a possible effect of flavonols on 2 measures - brain blood flow and a test they used to assess memory.
What did they find? No difference in the effects of flavonol-rich vs low in flavonol cocoas as 2 cups per night for 30 days.
However, they reported a significant improvement in blood flow and in the intellectual function test by 30 days.
Should we all now start drinking large amounts of cocoa? Not yet based in this interesting but small study. To consider my question in a different way, key points arising from this work are:
- does cocoa sharpen the mind?
- does it protect from dementia?
- does it help people with dementia?
With these points in mind:
- the study was small - only 60 participants included and only 18 of these were noted to have improvements with regular cocoa
- the study was only for 30 days - more work would be needed to show whether these apparent benefits would be sustained
- the study was performed in older people - average age 73, who already had risk factors for cardiovascular disease - not safe to generalise study findings to other age groups and to people without cardiovascular risk factors.
- the 70% of volunteers who had normal blood flow and managed the test well at baseline should no improvement with cocoa
- the study was designed to test an effect of flavonols. However there was no time control for the effect of cocoa - e.g. vs other hot drinks. The authors cannot therefore rule out a time effect on their results e.g. people not managing the test well at the start doing better simply through  the initial practice
- the tests of brain function were 'Trailing Making Tests' ie involved a timed 'joining the dots' test. It would be important to confirm that more real world aspects of brain function were also improved
- no patients with dementia were included - further studies would be needed to show whether patients with dementia would also benefit and that any benefits were helpful for activities of daily living 
Thus results of the study could be explained as an artefact of the study design - ie not be due to the cocoa. At best they only applied to people with identified cardiovascular factors who also already had impaired brain blood flow and difficulty in performing the type of mental activity tests used by the researchers. 
And the concern about large amounts of cocoa is the associated increase in dietary sugar and fat intake of typical Western milky cocoa drinks. Neither are good for cardiovascular health, as they increase risk of overweight, high cholesterol, diabetes and high blood pressure. To compensate for those risks, the researchers under the strict conditions of the study made sure their volunteers made appropriate adjustments in other parts of the diet to balance sugar and fat intake over the month. In real world use, even if cocoa were confirmed to be helpful for the brain, it would be very important that people increasing their cocoa intake were very careful to avoid these unintended consequences of increased cocoa intake. Of note the researchers were not studying cocoa with added cream and marshmallows - not good for the circulation.
What about different sources of chocolate in cocoa? Not addressed by the researchers - except that they appeared to show at least that any benefits were not related to the types of flavonol they studied.
And how about eating chocolate instead? Again - not studied by the researchers. And in previous observational research on chocolate, there was an apparent benefit on heart disease protection from very small amounts (chocolate 1-3 times per month) with larger amounts reported to be harmful for the heart.
As a final thought, one of the reported uses by ancient Aztecs and Incas of chocolate drinks was as sedatives in religious rituals. Another explanation for the study findings is that calming effects of cocoa ('soothing the soul') reduced anxiety during the tests as a contribution to the observed improvements in brain blood flow and test performance with the drinks.

Link to interview 8.8.13 with Shane O'Connor on BBC local radio

Provence, the Rhone estuary and the 'French paradox'

The ‘French paradox’, coined in 1992, refers to apparent unexpectedly low cardiovascular disease rates despite reported high exposure to factors predisposing to increased cardiovascular risk such as alcohol, cheeses high in saturated fats, and the stereotypical Gitane cigarette or modern equivalent. Obvious explanations for such a paradox include protective genetic factors, cardioprotective factors in the French lifestyle, and ascertainment bias in recording cardiovascular disease.
What insights are evident to explain the French paradox from visiting the Mediterranean reaches of the Rhone valley? Unlike for some northern European populations, the southern French are not averse to leafy green vegetables (the Provencal variant - ‘mesclun’), tomatoes, or other salad ingredients. And garlic and other alliums are popular in local recipes.
Cheese intake appears relatively low and goat and sheep’s cheese are popular. That raises an obvious question: does the species source of cheese matter for cardiovascular risk? Alcohol intake in public appears modest. That combined with evidence from Roger Corder and others for possible cardiovascular protective effects of certain red wines may contribute to reduced cardiovascular risk.
The typical local build is lean. However increasing numbers of young and older French men and women are developing abdominal obesity.
Smoking outdoors is still very prevalent, particularly among young women and men. There remains scope both for active and passive smoking to be continuing risk factors for increasing risk of cardiovascular disease.
What about access to health prevention and medical treatment? Every variety of doctor is available, with rooms in large and small towns, brass or marble plaques advertising their specialty, diploma – especially when from Paris, or even the gift of ‘expertise’. This health provision is complemented by a large number of pharmacies, and the newer vogue for parapharmacies, providing expertise and/or access to conventional, as well as plant-derived and other complementary remedies.
Do these other ‘remedies’ work? Certainly herbal and other plant extracts can have potent medical effects. For example, St John’s wort can reduce the expected clinical effects of treatment both by reducing absorption of drugs through activation of drug transporters in the gut, and by increase drug breakdown through activation of liver enzymes responsible for drug breakdown.
And grapefruit juice may lead to potentially serious interactions with over 50 prescribed and over-the-counter drugs, through reducing their breakdown, therefore leading to greater than expected effects of these medicines. Pomelos and Seville oranges may have similar actions.
The afternoon promenade is popular and there is ample opportunity for outdoor activity, whether from walking, more relaxed or extreme forms of cycling, riding the ‘wild’ Camargue horses, or active engagement in the local bull-friendly pursuit of trimming the bull’s fringe. This involves rapid evasive action from the charging bull, by leaps over high wooden barriers by the bull-trimmers (razeteurs). There is also ample opportunity to release aggression as a spectator, or as a participant in local bull- or horse-related spectacles.
Taken together, there are obvious dietary and lifestyle opportunities available in Provence to reduce cardiovascular risk. These are potentially offset by smoking, development of abdominal obesity and the degree to which exercise and alcohol feature in an individual’s lifestyle. And, at least for cardiovascular mortality, ascertainment is increasingly difficult, as fewer post-mortems are performed to verify cause of death.
The best strategy for cardiovascular prevention is effective public health advice, combined with effective management of cardiovascular risk factors by lifestyle and drugs, with advisors and members of the public well-motivated to adopt effective evidence-based measures to reduce cardiovascular risk. That of course begs several questions on existence or strength of the evidence base for cardio-protective effects of dietary factors, including different regional wines. These questions are key themes included within a Symposium on cardiovascular effects of ‘healthy foods’ to be held in London on Thursday 8th December 2011, with discussants including Professor Roger Corder (Wm Harvey Institute, London) and Professor KT Khaw (University of Cambridge).
For further details see my recent blog on 'What foods protect cardiovascular health?'

New ideas on diet and cardiovascular health?

What foods may actively help to promote the health of the heart, brain and circulation? And for people who have cardiovascular risk factors, heart disease or stroke syndromes, are there dietary factors that can reduce disease severity or prevent recurrent disease?

To address these and related questions outlined below, the CVRT organised an afternoon symposium on the 'Cardiovascular effects of ‘Healthy’ foods in London on Thursday 8th December, at the Medical Society of London rooms - 11 Chandos Street - 5 minutes walk from Oxford Circus. The symposium considered evidence and mechanisms for cardiovascular benefits (or not) of ‘healthy’ foods. A key message from KT Khaw was that healthy lifestyle actions are cumulative in protecting against serious disorders of the heart and circulation.

See weblink for the programme.

Too many calories, and high intake of saturated and transfats, are well recognised to increase risk of obesity, diabetes mellitus and accelerated vascular disease (atheroma) and low salt (sodium chloride) and potassium rich foods to confer cardiovascular protection.

Outstanding questions include whether particular types of macro-nutrient (protein, carbohydrate and fats) or micronutrients (vitamins, flavenoids, trace minerals) are protective. An association between dietary factor(s) and apparent cardiovascular benefit may be causative, due to 'reverse causation' [e.g. because healthier people believe in the link or are more likely to be able to afford particular dietary constituents]; or may be a coincidental association.

Speakers at the Symposium included Professor Roger Corder from the William Harvey Institute in London, Professor KT Khaw from the University of Cambridge and Associate Professor Naila Rabbani from the University of Warwick. KT Khaw  discussed current controversies, Naila Rabbani  bioactives in fruit and vegetables, and Roger Corder dietary polyphenols and potential vascular benefits of red wine and chocolate. And Jinit Masania outlined a new EU research programme, applying nutrigenomics to assess health claims made for foods.

This Symposium followed the July 2011 event on Exercise and Cardiovascular Health, also organized by the Cardiovascular Research Trust.

Further Symposia planned by the Cardiovascular Research Trust:
- 2nd Symposia on Cardiovascular Health, Diet and Exercise: Thursday 6th December 2012 

- 3rd Symposia on Cardiovascular Health, Diet and Exercise: Thursday 5th December 2013 

 

See blog on the French healthy heart 'paradox' 20 years on.

See also Dr Carolyn Staton’s excellent blog on 'Food and microcirculation' on the British Microcirculation Society site. 


© DRJ Singer