Vitamins & minerals
Seventh graders given 20 mg zinc, five days per week, for 10 to 12 weeks showed improvement in cognitive performance, responding more quickly and accurately on memory tasks and with more sustained attention, than classmates who received no additional zinc. Those who received only 10mg a day did not improve their performance. Previous studies have linked zinc nutrition to motor, cognitive and psychosocial function in very young children and adults, but this is the first study of its effect in adolescents. Adolescents are at particular risk of zinc deficiency, because they are undergoing rapid growth and often have poor eating habits. Red meats, fish and grains are good sources of zinc.
The findings were presented at Experimental Biology 2005, as part of the scientific sessions of the American Society of Nutritional Sciences.
A study of over 3,100 older men (49-71) from across Europe has found that men with higher levels of vitamin D performed consistently better in an attention and speed of processing task. There was no difference on visual memory tasks. Although previous studies have suggested low vitamin D levels may be associated with poorer cognitive performance, findings have been inconsistent. Vitamin D is primarily synthesised from sun exposure but is also found in certain foods such as oily fish.
 McCann, J. C., & Ames B. N.
(2008). Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction?.
FASEB J.. 22(4), 982 - 1001.
A review described as “definitive” has concluded that there is ample biological evidence to suggest an important role for vitamin D in brain development and function, and that supplementation for groups chronically low in vitamin D is warranted. Vitamin D has long been known to promote healthy bones, but more recently has been found to have a much broader role — over 900 different genes are now known to be able to bind the vitamin D receptor. Evidence for vitamin D's involvement in brain function includes the wide distribution of vitamin D receptors throughout the brain, as well as its ability to affect proteins in the brain known to be directly involved in learning and memory and motor control. Because we receive most of our Vitamin D from sunlight (UV from the sun converts a biochemical in the skin to vitamin D), those with darker skin living in northern latitudes are particularly at risk of vitamin D deficiency. Nursing infants and the elderly are also particularly vulnerable. It has also argued that current recommendations set the recommended level of vitamin D too low. This review is the fourth in a series that critically evaluate scientific evidence linking deficiencies in micronutrients to brain function. Earlier reviews have looked at DHA, choline, and iron.
 Casanueva, F. F., Finn J. D., Forti G., Giwercman A., Han T. S., Huhtaniemi I. T., et al.
(2009). Association between 25-hydroxyvitamin D levels and cognitive performance in middle-aged and older European men.
Journal of Neurology, Neurosurgery & Psychiatry. 80(7), 722 - 729.
A chemical called methionine (an amino acid found in beta-amyloid) may be the source of the toxic free radicals produced by the amyloid-beta peptide. Recent studies have demonstrated that higher than normal doses of vitamin E may slow the advance of Alzheimer's in some people with late stages of the disease. The current study provides a possible explanation for this link. Vitamin E, an antioxidant, appears to work by destroying free radicals (oxidants) produced by amyloid.
The study was presented at the 2000 International Chemical Congress of Pacific Basin Societies.
Two studies have come out in favor of a diet rich in foods containing vitamin E to help protect against Alzheimer's disease. One study involved 815 Chicago residents age 65 and older with no initial symptoms of mental decline, who were questioned about their eating habits and followed for an average of about four years. When factors like age and education were taken into account, those eating the most vitamin E-rich foods had a lower risk of developing Alzheimer’s, provided they did not have the ApoE e4 allele. This was not true when vitamin E was taken as a supplement. Intake of vitamin C and beta carotene appeared protective, but not at a statistically significant level. The other study involved 5,395 people in the Netherlands age 55 and older who were followed for an average of six years. Those with high intakes of vitamins E and C were less likely to become afflicted with Alzheimer's, regardless of whether they had the gene variation. This association was most pronounced for current smokers, for whom beta carotene also seemed to be protective. A number of clinical trials are underway to further investigate these links.
Engelhart, M.J., Geerlings, M.I., Ruitenberg, A., van Swieten, J.C., Hofman, A., Witteman, J.C.M. & Breteler, M.M.B. 2002. Dietary Intake of Antioxidants and Risk of Alzheimer Disease. JAMA, 287, 3223-3229. Morris, M.C., Evans, D.A., Bienias, J.L., Tangney, C.C., Bennett, D.A., Aggarwal, N., Wilson, R.S. & Scherr, P.A. 2002. Dietary Intake of Antioxidant Nutrients and the Risk of Incident Alzheimer Disease in a Biracial Community Study. JAMA, 287, 3230-3237.
A theory that changes in fat metabolism in the membranes of nerve cells play a role in Alzheimer's has been supported in a recent study. The study found significantly higher levels of ceramide and cholesterol in the middle frontal gyrus of Alzheimer's patients. The researchers suggest that alterations in fats (especially cholesterol and ceramide) may contribute to a "neurodegenerative cascade" that destroys neurons in Alzheimer's, and that the accumulation of ceramide and cholesterol is triggered by the oxidative stress brought on by the presence of the toxic beta amyloid peptide. The study also suggests a reason for why antioxidants such as vitamin E might delay the onset of Alzheimer's: treatment with Vitamin E reduced the levels of ceramide and cholesterol, resulting in "a significant decrease in the number of neurons killed by the beta amyloid and oxidative stress.
Cutler, R.G., Kelly, J., Storie, K., Pedersen, W.A., Tammara, A., Hatanpaa, K., Troncoso, J.C. & Mattson, M.P. 2004. Involvement of oxidative stress-induced abnormalities in ceramide and cholesterol metabolism in brain aging and Alzheimer's disease. PNAS, 101, 2070-5.
A study involving 4,740 elderly (65 years or older) found the greatest reduction in both prevalence and incidence of Alzheimer's in those who used individual vitamin E and C supplements in combination, with or without an additional multivitamin. There was no significant benefit in using vitamin C alone, vitamin E alone, or vitamin C and multivitamins in combination.
Zandi, P.P., Anthony, J.C., Khachaturian, A.S., Stone, S.V., Gustafson, D., Tschanz, J.T., Norton, M.C., Welsh-Bohmer, K.A. & Breitner, J.C.S. 2004. Reduced Risk of Alzheimer Disease in Users of Antioxidant Vitamin Supplements: The Cache County Study. Archives of Neurology, 61, 82-88.
A guinea pig study has found that newborn guinea pigs subjected to moderate vitamin C deficiency had 30% fewer hippocampal neurons and markedly worse spatial memory than guinea pigs given a normal diet. For several reasons the neonatal brain is thought to be particularly vulnerable to even a slight lowering of the vitamin C level. Vitamin C deficiency is very common in some parts of the world, and even in wealthy nations occurs in an estimated 5-10% of the adult population.
 Tveden-Nyborg, P., Johansen L K., Raida Z., Villumsen C K., Larsen J O., & Lykkesfeldt J.
(2009). Vitamin C deficiency in early postnatal life impairs spatial memory and reduces the number of hippocampal neurons in guinea pigs.
Am J Clin Nutr. 90(3), 540 - 546.
A new compound that boosts brain levels of magnesium improved many aspects of learning and memory in both young and old rats.
A rat study has found that increased levels of magnesium in the brain improved many aspects of learning and memory in both young and old rats. Because it is difficult to boost brain magnesium levels with traditional oral supplements, the researchers developed a new magnesium compound, magnesium-L-threonate (MgT). The cognitive improvements were associated with an increase in synapses and improved synaptic plasticity. It’s important to note that the control rats had a normal diet which is widely accepted to contain a sufficient amount of magnesium; thus the observed effects were due to elevation of magnesium to levels higher than provided by a normal diet. It is also estimated that half the population of industrialized countries has a magnesium deficit, which increases with aging. See here for a list of magnesium-rich foods.
 Slutsky, I., Abumaria N., Wu L-J., Huang C., Zhang L., Li B., et al.
(2010). Enhancement of Learning and Memory by Elevating Brain Magnesium.
Neuron. 65(2), 165 - 177.
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