Dietary choices play a role in one’s susceptibility to cognitive decline and dementia later in life. During the natural course of aging, cognitive reserve (the brain’s ability to recover from a neurological insult, like a concussion or drug overdose) is gradually depleted.
Loss of cognitive reserve capacity is particularly insidious because it can only be detected when it is too late for preventive measures to have a meaningful effect. The good news is that cognitive reserve can be maintained through positive lifestyle choices, including regular exercise, a rich and engaging social life and a diet comprised of brain healthy foods. One's "dose" of education (i.e., educational attainment), is also likely a protective factor. But the causal directionality of this observation is still unclear. (One possibility is that people with more resilient brains from the outset are more likely to attain terminal degrees, such as a PhD.)
So what are the best foods for overall brain health? Many tout nuts, blueberries and salmon as among the best brain superfoods.
We liked the evidence-based approach used in an article published by the European Journal of Clinical Nutrition (2010)* which compiled the polyphenol and flavonoid content of the hundred richest dietary sources of antioxidants using the Phenol-Explorer database. The Phenol-Explorer database has aggregated results on the polyphenol, flavonoid and antioxidant content of hundreds of foods based on a staggering number of peer-reviewed publications and experiments.
There is much controversy in the scientific community about whether antioxidants are a red herring or legitimately prevent disease. Perhaps the truth lies somewhere in the middle. But we believe that the evidence for the benefits of antioxidants is most robust in the context of cognitive wellbeing. The central nervous system is among the most metabolically active organ systems and is exquisitely sensitive to the oxidative environment in mitochondria. Mitochondria are the cellular energy powerhouses that supply ATP to neurons, the functional unit of the brain.
Because the brain is so energetically demanding, it produces the most unstable free radicals like superoxide. The brain therefore requires an adequate antioxidant defense, which if compromised, confers vulnerability to cognitive impairment.
If we omit seasoning like cloves, we obtain the following ranking of the most brain healthy foods:
- cocoa powder (7,846 mg/100g antioxidants)
- black chokeberry (4,940 mg/100g antioxidants)
- flaxseed meal (2,748 mg/100g antioxidants)
- black elderberry (4,113 mg/100g antioxidants)
- lowbush blueberry (1,803 mg/100g antioxidants)
- blackcurrant (2,043 mg/100g antioxidants)
- green olive (740 mg/100g antioxidants)
- sweet cherry (563 mg/100g antioxidants)
- artichoke hearts (1,010 mg/100g antioxidants)
- blackberry (1,010 mg/100g antioxidants)
These experimental results seem to vindicate the ubiquitous claim that blueberries, cocoa powder and artichoke hearts are among the best brain superfoods.
The raw data pulled from the Phenol Explorer database is shown below (reproduced from European Journal of Clinical Nutrition* (2010) **64, S112–S120; doi:10.1038/ejcn.2010.221). These data represent a ranking of the 100 most antioxidant rich foods based on a staggering number of independent experiments. Many common spices and ingredients in curry (e.g., tumeric) comprise the top of the list, which may explain why India has one of the lowest rates of neurodegenerative disease.
|Food||Polyphenols (mg/100g)||Polyphenols AE (mg/100g)||Antioxidants (mg/100g)|
|Mexican oregano (dried)||2319||2137||—|
|Common sage (dried)||1207||893||2920|
|Common thyme (dried)||878||464||1815|
|Sweet basil (dried)||322||166||4317|
|Globe artichoke heads||260||154||1142|
|Whole grain hard wheat flour||201c||201c||186|
|Common thyme (fresh)||163||118||1173|
|Refined maize flour||153c||153c||102|
|Whole grain rye flour||143c||143c||72|
|Lemon verbena (dried)||106||106||—|
|Whole grain wheat flour||71c||71c||90|
|Pure apple juice||68||61||34|
|Pure pomegranate juice||66||37||204|
|Extra-virgin olive oil||62||33||55|
|Pure blood orange juice||56||28||72|
|Pure grapefruit juice||53||23||54|
|Pure blond orange juice||46||20||—|
|Pure lemon juice||42||20||—|
|Whole grain oat flour||37c||37c||82|
|Refined rye flour||31c||31c||45|
|Chocolate beverage with milk||21||21||—|
|Pure pummelo juice||18||7.9||—|