Tea Protects Cognitive Function in the Elderly

A new paper has  highlighted the role of tea drinking on protecting brain function. Researchers tracked 957 people aged over 55 who all had normal cognitive function at the start and then assessed them a few years later as part of the Singapore Longitudinal Aging Study. They found that non-tea drinkers had almost twice the risk of developing neurocognitive disorder as consistent tea drinkers (11.1% vs 5.9%), and protection could start with just a few cups per week.

Interestingly, this study also looked at people who were carriers of the APOE ε4 gene, which is a gene variation that is linked with an increased risk of developing Alzheimer’s Disease. The researchers found that women and APOE ε4 carriers benefitted most from the protective effects of tea consumption.

As an important side note, in this paper cognitive decline was associated with higher rates of heart disease, depression and lower levels of social and productive activities, which previous research indicates might all share stress as an influencing factor.

Though the participants in this research were older Chinese adults the results are consistent with results with people from different backgrounds. As yet there is no cure for Alzheimer’s Disease and much of the focus of research in this area is on understanding its causes and finding preventative strategies. Encouraging people to drink a daily cup or two of green, black or oolong tea could be an effective and affordable way to help protect brain function in aging.

Reference

L. Feng, M-S. Chong, W-S. Lim, Q. Gao, M. S. Z. Nyunt, T-S. Lee, S. L. Collinson, T. Tsoi, E-H. Kua, & T. -P. Ng. Tea consumption reduces the incidence of neurocognitive disorders: Findings from the Singapore longitudinal aging study. The Journal of Nutrition, Health & Aging, 2016; 20 (10): 1002 DOI: 10.1007/s12603-016-0687-0

Dietary Fibre Linked with Improved Cognitive Control in Children

A correlation study conducted with small group of 7 and 9 year olds demonstrated a positive relationship between diet quality, in particular dietary fibre content, and performance on a task designed to assess attention and the ability to disregard distracting stimuli.

65 children undertook a modified version of the Erikson Flanker Test in which they were asked to pay attention to the direction of a fish in the centre of a computer screen and to try to ignore other fish that appeared on the screen at the same time that were facing either the same direction or the opposite direction of the target fish. Their results were correlated against food diaries that tracked a range of nutrients and subsets of nutrients. For example fats were broken down in to saturated fatty acids, cholesterol, omega-3s and DHA .

They found that children who had higher fibre diets had significantly improved accuracy scores on the Flanker test. The results showed that soluble fibre was associated with overall accuracy and pectin was particularly linked to accuracy in the version of the test that required greater effort. The researchers postulate that the effects might be linked to better control of blood sugar and/or the interaction of the gut microbiota. Fibre cannot be assimilated into the body but is highly fermentable by the bacteria in the gut. Some of the important end products of this fermentation are short-chain fatty acids, which have been linked to reduced inflammation in the brain and increased BDNF, compound associated with the creation of new brain cells.

Whilst this study was conducted on children it is highly likely that the outcomes will be similar in adults.

• High soluble fibre foods: Oats and oat bran, beans, lentils, apples, pears.
• High insoluble fibre foods: Wheat bran and wholegrains, brown rice, seeds, fruit and vegetable skins.
• High pectin foods: Apples, pears, quince, peaches, plums, oranges, lemons, grapefruit, gooseberries, apricots, guava, carrots, tomatoes.

Reference

Khan, N. A., Raine, L. B., Drollette, E. S., Scudder, M. R., Kramer, A. F., & Hillman, C. H. (2015). Dietary Fiber Is Positively Associated with Cognitive Control among Prepubertal Children. The Journal of Nutrition, 145(1), 143–149. http://doi.org/10.3945/jn.114.198457

Serum Vitamin D Predicts Cognitive Performance in Adults

Much of the research on the relationship between vitamin D and cognitive function has been conducted on older people or individuals who have a diagnosis of Alzheimer’s Disease or other dementia. This is because older people are less able to synthesise vitamin D in their skin and because dementia is typically a disease of aging. A study published in August 2015 looked at the relationship between vitamin D status and cognitive function in two cohorts of healthy individuals; those aged 30-60 and 60+. Research on disease-free groups is important because it allows us to look at the potential effect that nutritional deficiency has on the general population and on sub-clinical (no diagnosis) functioning. That is to say that we can learn more about how dietary insufficiencies might be affecting the general population long before disease onset. This information allows us more opportunity to intervene with treatment.

In this study of vitamin D in the blood were strongly associated with the degree of cognitive impairment on tests of visual spatial memory (recalling and recreating a complex shape) and processing speed. In this study lower levels of vitamin D were associated with poorer performance on these tests even in people aged 30.  This study complements a growing body of research that is demonstrating a relationship between vitamin D status and brain function (including influence on mood and anxiety disorders).

There is also growing concern worldwide about the ‘pandemic’ of vitamin D deficiency and the many health concerns it is associated with such as osteoporosis, fractures, and increased risk of some cancers and autoimmune diseases. It is estimated that at least 50% of people are vitamin D deficient and the situation is worse for those of with dark skin as the melanin pigment blocks the action of vitamin D synthesis in the skin. Food sources of vitamin D include oily fish (salmon, sardines and mackerel), eggs and fortified cereals, though few people are eating sufficient amounts of these foods to keep their levels topped up, and vegetarians and vegans need to be very thoughtful about their food/supplement choices to ensure adequate levels.

Reference

Darwish, H., Zeinoun, P., Ghusn, H., Khoury, B., Tamim, H., and Khoury, S. J. (2015). Serum 25-hydroxy vitamin D predicts cognitive performance in adults. Neuropsychiatric Disease and Treatment, 11, 2217–2223.