It is often considered that physiological and mental deterioration occurs inevitably during ageing. For example, muscle mass and blood pressure show detrimental physiological decreases and increases, respectively, as ageing proceeds. Mental function too shows a correlative decline with advancing years and a number of mental functions can be affected in this way. However, while this is normal and widely reported, there is uncertainty about whether this is inevitable. Most studies that have investigated decline in essential functions have been performed on aging Western populations, who largely consume a typical Western diet. Such diets are now known to cause Western lifestyle diseases many of which are characterised by the same physiological changes seen with advancing age. Studies of populations that consume the Mediterranean diet, for example in Sicily, do not show the same deterioration in mental and physical functions, supporting the view that diet and lifestyle plays a role in age-related decline.
A number of foods have been identified for their protective role in preventing age-related decline in both mental and physical essential functions. One category of such foods are the plant originating foods such as tea and red wine. Tea and red wine may be protective of age-related decline and Western lifestyle diseases because of the chemical phytonutrients they contain. Of these the polyphenols, a large group of heterogeneous phenolic chemicals, may be particularly beneficial due to their gene regulatory and antioxidant function. Another food that shares many similarities with tea and red wine is cocoa. Cocoa is also a rich source of polyphenols, particularly the large molecular weight proanthocyanidin class, a group of phytochemicals comprising of flavan-3-ol subunits. Cocoa may have health benefits that prevent age-related diseases including protection from cognitive decline. These functions of cocoa have been extensively investigated in human clinical trials.
In one study1, researchers investigated the possible cognitive benefits of cocoa consumption. Elderly subjects were fed either 993, 520 or mg per day of flavanols in drinks for 8 weeks. There was no significant difference between the groups when a medical examination of general cognitive function was given at the end of the 8 week treatment. However, specific aspects of cognitive function did improve. In particular, the high flavanol group showed improvements in a Trail Making Test and Verbal Fluency Test, compared to the medium or low flavanol group. The high flavanol and medium flavanol groups also displayed improvements in insulin resistance and blood pressure compared to the low flavanol group. As both insulin resistance and high blood pressure are possible contributory factor in cognitive decline, these improvements may have partially explained the improvements seen in cognitive function. In fact, insulin resistance improvements was estimated to account for 17 % of the cognitive improvements.
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