Recent findings boost the prevention reputation of the “sunshine and seafood” vitamin
by Craig Weatherby
It’s getting hard to keep up with the fast-growing flood of research on vitamin D, whose results uniformly put the long-overlooked “sunshine and seafood” vitamin in a positive light.
Last month, leading vitamin D researcher Michael Holick, M.D., of the Boston University School of Medicine repeated his colleagues’ call to raise the U.S. RDA from 200 IU to to 800 or 1000 IU per day (Holick MF, Chen TC 2008).
- Evidence review by renowned researcher Bruce Ames, Ph.D. detects vitamin D brain benefits and widespread U.S. deficiency.
- Lab findings support vitamin D’s observed link to reduced colon cancer rates.
- Analyses of U.S. health survey data links low vitamin D to increased risk of Peripheral Artery Disease (PAD) and risk factors for heart disease.
He and 15 other experts issued a similar plea last year: “We call for international agencies… to reassess as a matter of high priority their dietary recommendations for vitamin D… public health is best served by a recommendation of higher daily intakes...” (Vieth R, et al. 2007).
These experts included nutrition guru Walter Willett, M.D., of the Harvard School of Public Health, with whom we had the pleasure to speak at the recent “Healthy Kitchens, Healthy Lives” conference (See “Vital Choice Fish Feeds CIA-Harvard Culinary Conference”).
To read about prior findings concerning vitamin D’s effect on cancer and other health conditions—and the downside to doctors’ overblown sun-avoidance advice—search our newsletter archives for “vitamin D.”
Let’s take a quick look at each of three recent studies that confirm the overlooked importance of vitamin D.
Vitamin D pills urged to protect aging brains
When renowned UCLA researcher Bruce Ames, Ph.D. speaks, other scientists listen hard.
Dr. Ames is one of the most widely published and respected researchers of the past 50 years. He is best known as the inventor of what became known as the “Ames test”, which is still used worldwide to gauge the toxicity of chemicals.
Fish fit the vitamin D bill; Sockeye salmon stand out
Certain fish rank among the very few substantial food sources of vitamin D.
Among fish, wild Sockeye Salmon may be the richest source of all, with a single 3.5 ounce serving surpassing the US RDA of 400 IU by about 70 percent:
Vitamin D per 3.5 ounce serving*
Sockeye Salmon—687 IU
Albacore Tuna—544 IU
Silver Salmon—430 IU
King Salmon—236 IU
*For our full test results, click here.
Last year, he and colleague Joyce McCann released an evidence review, in which they concluded that vitamin D is likey related to brain health, and recommended supplements to the many Americans with low vitamin D levels (McCann JC, Ames BN 2008).The pair noted that the need is especially urgent for nursing infants, the elderly, and African Americans, because vitamin D levels are exceptionally low among these three groups.
Because of Americans’ low intake of vitamin D from foods or supplements—and the lack of sun exposure among people living in northern states or who work indoors— estimates are that as many as 60 percent of us may be vitamin D deficient.
In adults, vitamin D deficiency is associated with increased risk of osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases.
In his new paper, Dr. Ames notes the wide distribution of vitamin D receptors throughout the brain, and underscores the role of the vitamin in maintaining brain health.
He emphasized that vitamin D appears to affect brain proteins responsible for learning and memory, motor control, and behavior.
Although the evidence remains inconclusive, the results of previous human and animal studies indicate that inadequate vitamin D levels may impair cognition and give rise to behavior problems.
As Drs. Ames and McCann wrote, “We conclude there is ample biological evidence to suggest an important role for vitamin D in brain development and function… recommendations for vitamin D supplementation of at-risk groups, including nursing infants, the elderly, and African-Americans appear warranted to ensure adequacy” (McCann JC, Ames BN 2008).
Reasons for apparent colon benefits pinpointed
Colorectal cancer is the second leading cause of cancer deaths in the United States.
If diagnosis is made early, it’s one of the most curable cancers. But despite advances in screening methods and treatments, the death rate hasn’t declined much over the last 30 years.
Epidemiological studies suggest strongly that vitamin D and calcium may protect against colorectal cancers.
We should note that the authors of the large Women's Health Initiative (WHI) clinical trial reported that vitamin D and calcium supplements did not appear to cut participants’ risk of colon cancer (Wactawski-Wende J et al 2006).
However, the soundness of this conclusion was challenged by researchers at the University of Texas M.D. Anderson Cancer Center, who wrote that the study’s complexities made this conclusion unreliable (Forman MR, Levin B 2006).
And last month, researchers reported the results of clinical and epidemiological (case-control) studies, which affirm these nutrients’ combined ability to deter colon cancer development, and help explain how they bring this benefit about.
The new studies indicate that together, vitamin D and calcium increase body levels of chemicals that discourage development and spread of colon cancer.
The clinical trial looked at the effects of vitamin D and calcium on a protein called Bax, which helps control programmed cell death (apoptosis) in the colon: a process that is a primary way the body deals with budding cancers.
As the researchers reported, “…these preliminary results suggest that… calcium and vitamin D, individually or together, may enhance apoptosis in the human colorectal epithelium [organ lining]” (Fedirko V et al. 2008).
The case-control study looked at the effects of vitamin D and calcium on two chemicals that interact to inhibit pre-cancerous changes in colon cells, called beta-catenin and E-cadherin.
The conclusion was encouraging: “…expression of both beta-catenin and E-cadherin (especially E-cadherin) in persons who were consuming high amounts of calcium and vitamin D were substantially… [higher than] those in persons who were consuming low amounts of both nutrients together or high amounts of only one nutrient or the other alone” (Thomas A et al. 2008).
High dietary intakes of red meat and iron are considered risk factors for colon cancer: and findings from the same conference strengthen suspicions that these factors promote colon cancer (Dash C et al. 2008).
Vitamin D may enhance artery health
Last year, researchers from Charles R. Drew University of Medicine and Science in Los Angeles analyzed data from the National Health and Nutrition Examination Survey (NHANES), which collects both lifestyle data and blood samples from participants.
Among the 15,088 participants studied, they found that those with the lowest levels of vitamin D had substantially higher rates of four risk factors for cardiovacular disease:
- Hypertension (30 percent higher rate)
- Diabetes (98 percent higher rate)
- Obesity (29 percent higher rate)
- Elevated blood triglyceride levels (47 percent higher rate).
Now, the results of another analysis of data from NHANES volunteers seem to extend the protective effects of vitamin D to the risk of developing Peripheral Artery Disease.
Peripheral Artery Disease (PAD) results from fatty deposits (plaque) that build up in the arteries outside the heart (peripheral arteries); mainly the arteries supplying the legs and feet.
This buildup reduces the amount of blood and oxygen delivered to leg muscles and feet.
According to the American Heart Association, PAD affects about 8 million Americans and is associated with significant disease and death.
Researchers at the Albert Einstein College of Medicine in New York City analyzed data from 4,839 NHANES participants (Melamed ML et al. 2008).
After accounting for the impact on PAD risk associated with age, sex, race and co-existing health problems, they found that PAD was 64 percent more common in the group with the lowest vitamin D levels compared with the group with the highest levels.
For every drop in vitamin D levels of 10 nanograms per milliliter (ng/mL), the risk for PAD increased by 29 percent.
And this correlation was consistent across various demographic subgroups: a finding the researchers called “noteworthy”.
This statistical relationship does not prove that higher blood levels of vitamin D protect against PAD, but lead researcher Michael Melamed, MD, recommends that people obtain vitamin D “…either through exposure to the sun or from foods, especially fish and fortified milk and other fortified foods” (Melamed ML et al. 2008).
- Dash C, et al. Abstract 5504. High dietary iron levels and expression of Wnt pathway proteins in colon crypts of colorectal adenoma patients. 2008 American Association for Cancer Research Annual Meeting; April 13, 2008.
- Fedirko V, Bostick RM, Flanders WD, Long Q, Cohen V. Abstract 464. Effect of vitamin D and calcium supplementation on markers of apoptosis in normal colon mucosa: Results from a randomized clinical trial. 2008 American Association for Cancer Research Annual Meeting; April 13, 2008,
- Forman MR, Levin B. Calcium plus vitamin D3 supplementation and colorectal cancer in women. N Engl J Med. 2006 Feb 16;354(7):752-4. No abstract available. Erratum in: N Engl J Med. 2006 Mar 9;354(10):1102.
- Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr. 2008 Apr;87(4):1080S-6S. Review.
- McCann JC, Ames BN. Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction? FASEB J. 2008 Apr;22(4):982-1001. Epub 2007 Dec 4.
- Melamed ML, Muntner P, Michos ED, Uribarri J, Weber C, Sharma J, Raggi P. Serum 25-Hydroxyvitamin D Levels and the Prevalence of Peripheral Arterial Disease. Results from NHANES 2001 to 2004. Arterioscler Thromb Vasc Biol. 2008 Apr 16. [Epub ahead of print]
- Thomas A, Dash C, Bostick RM. Abstract 565. Associations of calcium and vitamin D with E-cadherin and ß-catenin expression in normal-appearing rectal tissue; markers of adenomatous polyps II (MAP II) case-control study. 2008 American Association for Cancer Research Annual Meeting; April 13, 2008.
- Vieth R, Bischoff-Ferrari H, Boucher BJ, Dawson-Hughes B, Garland CF, Heaney RP, Holick MF, Hollis BW, Lamberg-Allardt C, McGrath JJ, Norman AW, Scragg R, Whiting SJ, Willett WC, Zittermann A. The urgent need to recommend an intake of vitamin D that is effective. Am J Clin Nutr. 2007 Mar;85(3):649-50. Erratum in: Am J Clin Nutr. 2007 Sep;86(3):809.
- Wactawski-Wende J et al; Women's Health Initiative Investigators. Calcium plus vitamin D supplementation and the risk of colorectal cancer. N Engl J Med. 2006 Feb 16;354(7):684-96. Erratum in: N Engl J Med. 2006 Mar 9;354(10):1102.