An ecological study found total fat intake, along with total energy supply, highly correlated with Alzheimer's disease (AD) prevalence – with fish and cereals inversely correlated (Grant, 1997). These findings initiated the AD-dietary hypothesis, which continues to gain support. For example, a recent study in Poland found that the AD dietary pattern was characterized by a high intake of processed meat, butter, high-fat dairy products, eggs, and refined sugar, while the control pattern was characterized by a high intake of grains and vegetables (Gustaw-Rothenberg, 2009). An additional contributing factor to AD is the genetic risk based on apolipoprotein ε4 (ApoE4), which increases both cholesterol and insulin production (and weight in conjunction with a high-energy diet). ApoE4 is an important consideration for African Americans.
The 1997 study noted that because AD patients' brains have elevated concentrations of aluminum and transition metal ions, along with a reduced concentration of calcium, the dietary findings were consistent with a lower pH level in the digestive tract. The "metals hypothesis", i.e., metal-catalyzed hydroxyl radicals damage neurons, has gained considerable support (Bush and Tanzi, 2008). Although dealing with the aftermath of a long-term unhealthy diet by using chelation therapy or drugs might be indicated, eating with brain and general health in mind seems a more reasonable and practical measure.
Vitamin D is the current wonder compound, gaining increasing recognition for reducing the risk of many chronic and infectious diseases and mortality rates. Recently, interest has also extended to studying vitamin D's benefits for the brain. Several recent observational studies reported an inverse correlation between prevalence of cognitive impairment and serum 25-hydroxyvitamin D [25(OH)D] levels, such as one in the UK (Llewellyn et al., 2009). In this study, a serum 25(OH)D level in the lowest quartile (3–12 ng/ml) was correlated with an odds ratio of cognitive impairment of 2.3 (95% confidence interval, 1.4–3.8) compared with those in the fourth quartile (26–68 ng/ml) after adjustment for confounding factors.
Because cognitive impairment is often a precursor of dementia, it is reasonable to expect that low serum 25(OH)D levels would also be a risk factor for dementia (Grant, 2009). Other diseases that seem to precede dementia, and for which risk increases with lower serum 25(OH)D levels, include cardiovascular disease, diabetes, and tooth loss from either dental caries or periodontal disease (Grant, 2009).
On the basis of cross-sectional and observational studies, and randomized controlled trials of non-neurological diseases, serum 25(OH)D levels of 40–60 ng/ml are considered optimal. For each 1000 International Units (IU)/day of vitamin D production or oral intake, serum 25(OH)D levels increase by 6–10 ng/ml. Because mean population serum 25(OH)D levels range from 16 to 30 ng/ml, 2000–4000 IU/day of vitamin D from UV-B irradiance and/or oral intake would be indicated.
Thus, there appear to be two good ways to reduce the risk of cognitive impairment and dementia: diet modification and increased vitamin D.
AcknowledgmentsI receive funding from the UV Foundation (McLean, VA), the Vitamin D Society (Canada), the Sunlight Research Forum (Veldhoven), and Bio-Tech-Pharmacal (Fayetteville, AR).
ReferencesGrant, W. B. (1997). Dietary links to Alzheimer's disease. Alz. Dis. Rev. 2, 42-55. (http://www.sunarc.org/JAD97.pdf)BiographyWilliam B. Grant obtained a Ph.D. in Physics, University of California, Berkeley, in 1971. His professional career was devoted to developing and using laser systems for the remote sensing of atmospheric constituents such as aerosols and ozone, including 15 years with the NASA Langley Research Center. In Virginia, he performed an ecological study of the effects of acid rain on eastern hardwood forests, which led to his seminal paper on diet and Alzheimer's disease. He turned his attention to the health benefits of vitamin D in 2000, moved to San Francisco, and founded SUNARC in 2004.
wbgrant@infionline.net
Saturday, May 29, 2010
William B. Grant - Brain Food and Vitamin D
Excellent article from Frontiers in Neuroscience - vitamin D is much more crucial than people ever thought.
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