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Back to Roles on Certain Health Conditions

Cognitive Function and Milk Products

Emerging evidence suggests that milk products may play a beneficial role in improving cognitive function and thus aid in thought processing and mental ability.

Highlights

  • A high-dairy diet appears to improve working memory performance;
  • A lower consumption of milk and milk products has been associated with poorer cognitive function and an increased risk for vascular dementia;
  • Total dairy consumption, as well as cheese consumption, has been shown to aid cognitive function in both younger adults and the elderly.

Few studies have been conducted to investigate potential associations between milk products and cognitive health. Evidence from recent studies indicates that milk products, including cheese, may help enhance cognitive function.

Various components in milk have been identified as part of the underlying mechanisms that may help brain function. These components include:

The Evidence

In a 2012 randomized, crossover dietary intervention trial, the consumption of low-fat dairy was investigated as a means to improve cognitive function. Fifty-nine overweight or obese adults aged 18 to 75 years who had a low usual intake of milk products were enrolled. Participants were randomized to a high-dairy or low-dairy diet (5 vs. 1 serving of reduced-fat dairy per day). The trial lasted for 12 months, with crossover to the alternate diet at 6 months. Significantly higher working memory scores were obtained after the high-dairy diet compared to the low-dairy diet.1

A 2010 systematic review also evaluated the association between milk products and cognitive function.2

  • Limited evidence from a small number of observational studies, including prospective cohort and cross-sectional studies, suggested that a lower consumption of milk and milk products is associated with poorer cognitive function and an increased risk for vascular dementia;
  • It was concluded that milk products may be beneficial for the prevention of cognitive decline.

In a 2012 cross-sectional study, data from the National Health and Nutrition Examination Surveys (NHANES 1988-94 and 1999-2002) was used to examine whether milk product intake was associated with cognitive function. Analyses of the NHANES 1988-94 database were conducted for 4,355 adults aged 20 to 59 years and 4,282 adults aged 60 years and over. Analyses from the NHANES 1999-2002 consisted of 2,189 adults aged 60 years and over. The results demonstrated associations between milk products and cheese and improved cognitive function:3

  • In individuals aged 20 to 59 years, total dairy consumption was associated with a higher global cognitive percentile score compared to non-consumption;
  • Cheese consumption in the younger age group was associated with a higher score on a symbol-digit substitution test (a test of information-processing speed, concentration and motor control), with a score of 55.2 for the highest quartile of consumption vs. 49.0 for no consumption (p < 0.001);
  • In the older age group, higher percentile scores from the short-term memory measurements were obtained for total dairy consumption as well as for cheese consumption;
  • Among the elderly, milk product intake was associated with a higher score on digit-symbol substitution test (a neuropsychological test which is a sensitive measure to brain damage and dementia).

Another 2012 cross-sectional analysis was conducted to assess whether there was an association between milk products and cognitive function in 972 adults from the community-based Maine-Syracuse Longitudinal Study.4

  • A significant linear trend in cognitive scores was found with increasing milk product intake, with the highest scores for subjects who had the highest consumption;
  • After adjustment for cardiovascular risk factors, lifestyle and dietary factors, subjects who consumed milk products at least once per day had significantly higher scores in multiple domains of cognitive function compared to those who never or rarely consumed milk products.

Potential Mechanisms

It has been suggested that milk products have a beneficial impact on cognitive health through improvements in cardiovascular risk factors and metabolic syndrome components, which are factors that have been linked to detrimental brain damage.1 In addition, calcium and whey protein may also be important through their associated role in glucose regulation and weight management.5

Various other dairy components may also have a direct effect on brain function. For example, bioactive peptides with anti-oxidative properties may enhance cognitive ability by preventing oxidative stress in the nervous system.5

As a good source of tryptophan (an amino acid precursor of serotonin), α-lactalbumin in milk has also been shown to raise brain serotonin levels. It has been suggested that an increased serotonin level has beneficial effects on mood and cognitive function, including information processing. Higher serotonin levels may also attenuate the effects of reduced neurogenesis due to stress and aging.5

Vitamin B12 in milk and milk products may also play a role in cognitive function and healthy brain aging. Epidemiological studies have linked vitamin B12 deficiency to an increased risk of Alzheimer’s disease.5,6

Conclusion

Evidence exists on the association between milk products and cognitive function, but it is limited. To date, the evidence suggests that total dairy as well as cheese consumption may be associated with improved cognitive function.

More research, including randomized controlled trials, is needed to clarify the association between milk products and cognitive health. Mechanistic studies are also needed to understand the action of various dairy components in preventing cognitive impairment.

Keywords: bioactive peptides , whey protein


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