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Key Points
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New population studies link low vitamin D levels to higher breast, heart, and death risks.
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The findings echo those of earlier population studies from America and Europe.
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Clinical trials are needed to prove a cause-effect relationship between low vitamin D and major health risks.
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Few Americans have the vitamin D blood levels recommended by leading university researchers.
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Now, the results of a new University of Colorado analysis of health data from 3,400 Americans affirms the prior reports linking low vitamin D levels to higher death and heart risks.
And a Columbia University study published in June once again links low vitamin D levels to higher breast cancer risks.
Let’s take a closer look at both of the new American studies.
National survey data links death and heart risk to low vitamin D levels
The results of a “case-control” study indicates that older people with low blood levels of vitamin D may be 2.5 times more likely to die from any cause – and three times more likely to die from heart disease.
These risks were calculated in comparison to people with adequate levels of the “sunshine and seafood” vitamin.
To arrive at the new findings, a team from the University of Colorado-Denver School of Medicine compared medical data collected from 3,488 people aged 65, including their medical records and blood test results (Ginde AA et al. 2009).
The subjects were participating in the Third National Health and Nutrition Examination Survey. They enrolled between 1988 and 1994 and were followed until 2000.
After an average of 7 years of follow-up, 1,493 people died, including 767 who died from cardiovascular disease.
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Fish fit the vitamin D bill; Sockeye salmon stand out
In addition to getting vitamin D from supplements, certain fish rank among the very few substantial food sources of vitamin D, far outranking milk and other D-fortified foods.
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
Sardines 222 IU
Sablefish 169 IU
Halibut 162 IU
*For our full test results, click here.
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Compared to those with optimal vitamin D status (at least 100 nmol/L), those with low vitamin D levels (25 nmol/L) were three times more likely to have died from heart disease and 2.5 times more likely to have died from any cause.
Vitamin D deficiency is linked to high blood pressure and inflammation, which plays a strong role in all kinds of heart disease.
Indeed, the Austrian study published last year found that people with the lowest vitamin D levels also had the highest levels of three key risk factors for cardiovascular disease: inflammation, oxidative stress (an excess of free radicals), and cell adhesion (blood stickiness).
Lead author Adit Ginde, M.D., M.P.H., said that the findings suggest that current daily recommendations of vitamin D – 400 IU for people aged 51-70 and 600 IUs for people 71 and older – may not be enough for older adults to maintain optimal health.
Commenting on the study, senior cardiac nurse June Davison of the British Heart Foundation noted that while the Colorado study found a link between low vitamin D levels, death, and heart disease, more “research is needed in this area before we can assume a casual effect.”
But as she also said, “Oily fish is a good source of vitamin D, so it's another reason to eat at least one portion a week to help keep your heart healthy.”
The Colorado team has applied for funding to perform a large clinical trial in which older adults would take vitamin D supplements, to see if that will improve survival rates and reduce the risk of developing heart disease.
New breast study affirms link to low vitamin D levels
In a study that affirms the results we reported last year, researchers at Columbia University in New York City analyzed data from an earlier case-control study on Long Island (Crew KD et al. 2009).
In the original study, in-person interviews and blood specimens were obtained from 1,026 breast cancer patients and 1,075 healthy controls.
The new analysis showed that women with higher vitamin D blood levels were 44 percent less likely to have a breast cancer diagnosis.
The reduction in risk – 54 percent – was even greater among postmenopausal women.
And the risk reduction applied to breast tumors with different kinds of hormone receptors.
As they wrote, “... these results add to a growing body of evidence that adequate vitamin D stores may prevent breast cancer development.” (Crew KD et al. 2009)
And they went on to say that the data suggest that the optimal blood level for breast cancer prevention is 40 ng/mL or more.
Most researchers say that the minimum healthful level of vitamin D is 36 to 48 ng/mL – which is the same thing as 90 to 120 nmol/L – or more.
Thus, the Columbia team’s recommendation for breast cancer prevention aligns perfectly with the expert consensus on the minimum level for overall health.
We’d second their final words: “Well-designed clinical trials are urgently needed to determine whether vitamin D supplementation is effective for breast cancer chemoprevention.” (Crew KD et al. 2009)
Sources
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Bischoff-Ferrari HA. Optimal serum 25-hydroxyvitamin D levels for multiple health outcomes. Adv Exp Med Biol. 2008;624:55-71. Review.
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Crew KD, Gammon MD, Steck SE, Hershman DL, Cremers S, Dworakowski E, Shane E, Terry MB, Desai M, Teitelbaum SL, Neugut AI, Santella RM. Association between plasma 25-hydroxyvitamin D and breast cancer risk. Cancer Prev Res (Phila Pa). 2009 Jun;2(6):598-604. Epub 2009 May 26.
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Ginde AA, Scragg R, Schwartz RS, Camargo CA Jr. Prospective Study of Serum 25-Hydroxyvitamin D Level, Cardiovascular Disease Mortality, and All-Cause Mortality in Older U.S. Adults. J Am Geriatr Soc. 2009 Jun 22. [Epub ahead of print]
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Heaney RP. Vitamin D in health and disease. Clin J Am Soc Nephrol. 2008 Sep;3(5):1535-41. Epub 2008 Jun 4.
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Melamed ML, Michos ED, Post W, Astor B. 25-hydroxyvitamin D levels and the risk of mortality in the general population. Arch Intern Med. 2008 Aug 11;168(15):1629-37.
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Vieth R, Chan PC, MacFarlane GD. Efficacy and safety of vitamin D3 intake exceeding the lowest observed adverse effect level. Am J Clin Nutr. 2001 Feb;73(2):288-94.
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Wagner CL, Greer FR, Section on Breastfeeding and Committee on Nutrition. Prevention of Rickets and Vitamin D Deficiency in Infants, Children, and Adolescents Accessed online October 13, 2008 at http://www.aap.org/new/VitaminDreport.pdf
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