Higher levels of the sunshine-and-seafood vitamin appear to improve brain function and mood in older adults
by Craig Weatherby
We can now add Alzheimer's prevention to the roster of vitamin D's probable health powers.
Vitamin D develops in skin cells exposed to UV sunrays. Fish are the best foods sources, but it occurs in uncommon abundance in certain fatty fish, including tuna and wild Salmon—especially Sockeye.
Twin studies affirm vitamin D-Alzheimer's link
In an unplanned coincidence, teams at two separate U.S. universities published recent studies that combine to offer new promise for the “sunshine-and-seafood” vitamin.
Study #1: Alzheimer's patients found deficient in vitamin D
Table #1 US RDA=400 IU Raw Fish (3.5 oz)* Vitamin D (IUs) Wild Salmon (species unspecified) 988 Ahi Tuna 404 Farmed Trout 388 Bluefish 280 Farmed Salmon 245 Cod 104 Gray Sole 56 Mackerel 24
US RDA=400 IU
Raw Fish (3.5 oz)*
Vitamin D (IUs)
Wild Salmon (species unspecified)
Last December, researchers at the Washington University School of Medicine published the results of a study in 80 elderly people: 40 with mild Alzheimer's disease and 40 without any form of dementia, selected from among participants in a long-term study of memory and aging (Wilkins CH et al 2006).
The scientists wanted to further explore the fact that, as they said, “Vitamin D deficiency is common in older adults and has been implicated in psychiatric and neurologic disorders.”
They assessed the participants' vitamin D levels, cognitive functions, mood, and physical performance using standard tests and clinician's diagnoses.
The majority (58 percent) had abnormally low vitamin D levels—defined as less than 20 ng/mL (nano grams per liter)—and the average vitamin D level in the group of 80 was only 18.58 ng/mL.
After adjusting the results for age, race, gender, and the season during which vitamin D levels were tested, the outcomes showed that the participants deficient in vitamin D were 88 percent more likely to have a mood disorder such as depression or anxiety.
And, compared to people with higher vitamin D levels, participants deficient in vitamin D performed worse on two out of four mental performance tests.
As the Washington University team concluded, “…vitamin D deficiency was associated with low mood and with [mental] impairment…”
Study #2: People deficient in vitamin D score worse on mental tests
US RDA=400 IU
Vital Choice Tests
Raw Fish (3.5 oz Vitamin D servings)** (IUs)
Sockeye Salmon 687
Albacore Tuna 544
Silver Salmon 430
King Salmon 236
This study was followed by one by researchers at University of Wisconsin-Madison, which probed for any associations between vitamin D levels and cognitive function, and explored potential explanations for such links (Przybelski RJ, Binkley NC 2007).
The researchers also looked for any relationship between vitamin B12 status and cognitive capacities.
They analyzed medical charts belonging to 32 older adults who'd come to a university-affiliated clinic and received assessments of their memory and mental capacities and had had their vitamin D and vitamin B12 levels tested as well.
Those with higher vitamin D levels had also scored higher on the mental tests, but no such effect was seen in the people with higher B12 levels.
As the Wisconsin team wrote, the significant correlation between vitamin D levels and mental test scores in these patients “…suggests a potential role for vitamin D in cognitive function of older adults.”
It is interesting to note that an earlier study suggests that compared with young people, age-related declines in people's kidney function may require older people to ingest more vitamin D to maintain the same blood levels (Vieth R, Ladak Y, Walfish PG 2003).
*Lu Z et al 2007. Note: When the researchers baked a 3.5 oz serving of Farmed Salmon, it lost only 5 IU of vitamin D, but when it was fried in vegetable oil, it lost half of its vitamin D content (122 IU out of 245 IU).
**Vital Choice fish analysis conducted by Covance Laboratories, Inc.; accessible at http://www.vitalchoice.com/uploads/Vitamin%20D%20chart%20&%20Data6.pdf.
- Przybelski RJ, Binkley NC. Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function. Arch Biochem Biophys. 2007 Jan 8; [Epub ahead of print]
- Wilkins CH, Sheline YI, Roe CM, Birge SJ, Morris JC. Vitamin D deficiency is associated with low mood and worse cognitive performance in older adults. Am J Geriatr Psychiatry. 2006 Dec;14(12):1032-40.
- Vieth R, Ladak Y, Walfish PG. Age-related changes in the 25-hydroxyvitamin D versus parathyroid hormone relationship suggest a different reason why older adults require more vitamin D. J Clin Endocrinol Metab. 2003 Jan;88(1):185-91.
- Lu Z, Chen TC, Zhang A, Persons KS, Kohn N, Berkowitz R, Martinello S, Holick MF. An evaluation of the vitamin D(3) content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D? J Steroid Biochem Mol Biol. 2007 Jan 29; [Epub ahead of print] doi:10.1016/j.jsbmb.2006.12.010
- Whiting SJ, Green TJ, Calvo MS. Vitamin D intakes in North America and Asia-Pacific countries are not sufficient to prevent vitamin D insufficiency. J Steroid Biochem Mol Biol. 2007 Jan 9; [Epub ahead of print]
- Holick MF. High prevalence of vitamin D inadequacy and implications for health. Mayo Clin Proc. 2006 Mar;81(3):353-73. Review.