A Spoonful of Sunshine

A Spoonful of Sunshine: The Vitamin D Picture Matures By Stephen A. Levine, Ph.D.

The much-discussed August 2010 issue of Focus was devoted entirely to vitamin D and received tremendous positive feedback from physicians. We offered an in-depth distillation of the peer-review literature, explored the profound cross-talk that occurs between vitamins D and A, presented the views of experts in vitamin K, D and A,  and supported a balanced approach to supplementation of this pro-hormone, making sure that other fat-soluble vitamins are not ignored. Two of the most important insights from that newsletter were that 1) too much vitamin D and too little vitamin A will create a functional deficiency of vitamin A with associated immune issues and 2) testing is mandatory for anybody concerned about vitamin D levels, as individual variation is so great.

Since that time, numerous exciting studies on vitamin D have been published, showing that a deficiency of vitamin D is connected to illnesses such as breast cancer, multiple sclerosis, and cardiovascular disease. As the picture matures, a balanced approach is the consensus.

In November, the big news came from the Institute of Medicine (IOM), which for the first time since 1997 issued new recommendations on safe levels of vitamin D supplementation. They called for at least 600 IU of vitamin D daily up to age 70, and 800 IU daily after age 71. They raised the safe upper limit of 2000 IU daily to 4000 IU daily for adults. This minimum and maximum safe range is right in line with the levels recommended by vitamin D expert Krispin Sullivan , CN in the August Focus, and is supported by the scientific literature. However, any supplementation must be based on regular testing of vitamin D levels, given the great variability in individual sun exposure, genetics, and diet.

Not surprisingly, there was still some pushback against the IOM’s new recommendations, especially the 600 IU daily. A source no less prestigious than the Harvard School of Public Health Nutrition Source offered commentary co-authored by Heike A. Bischoff-Ferrari, MD, DrPH and Walter C. Willett, MD, DrPH, who noted that the IOM’s recommended safe threshold of 50 nmol/l (20 ng/ml) for 25(OH)D was not adequate for preventing fractures. In contrast to the IOM report, the International Osteoporosis Foundation (IOF) 2010 position paper had recommended a threshold of 75 nmol/l (30 ng/ml) for optimal fall and fracture reduction and recommended 800 to 1,000 IU of vitamin D per day for seniors age 60 years and older.(1) The Harvard newsletter approved of the upper limits: “In support of a greater safety margin in research and supplementation strategies, the IOM doubled the safe upper limit from 2,000 IU to 4,000 IU of vitamin D per day, which is appropriate.”(2)

In other news reflecting the complexity of the Vitamin D picture, a study presented at the American Association for Cancer Research (AACR) 102nd Annual Meeting in 2011 found that vitamin D significantly reduced development of estrogen receptor-positive breast cancer in both lean and obese mice, but had no beneficial effect on estrogen receptor-negative cancer. The researchers, from the Georgetown Lombardi Comprehensive Cancer Center found that Vitamin D reversed insulin resistance in obese mice, but did not reduce insulin sensitivity in lean mice. In earlier studies from the Lombardi Center, vitamin D reversed both early and advanced endometrial cancer in obese mice, but had no benefit on the same cancer in lean mice. The lead researcher, oncologist Leena Hilakivi-Clarke, PhD concluded: “For those who want to boost their use of vitamin D, it is important that they have their individual levels tested by a physician, and that they discuss their desire to use supplements."(3) We might add that it would be useful to look at vitamin A in these conditions, since retinoic acid derivatives are being studied in cancer.

The cardiovascular connection to vitamin D was highlighted in a new study suggesting that a lack of the vitamin may be linked with stiffer arteries. The research comes from the Emory/Georgia Tech Predictive Health Institute. The findings were presented at the annual American College of Cardiology meeting in New Orleans. 554 participants in the study were Emory or Georgia Tech employees –average age 47 and generally healthy. The researchers monitored the ability of participants’ blood vessels to relax by inflating and then removing a blood pressure cuff on their arms. As blood flows back into the arm, blood vessels relax and enlarge – which can be measured by ultrasound. Resistance to blood flow imposed by the arteries can be measured in smaller blood vessels as well. Even after controlling for factors such as age, weight and cholesterol, people with vitamin D deficiency had vascular dysfunction comparable to those with diabetes or hypertension.(4)

A new study confirms that low sunlight exposure and low Vitamin D raises risk of multiple sclerosis, according to a new study published in Neurology in February, 2011.  The multi-site study looked at 216 people age 18 to 59 who had a first event with symptoms of the type seen in multiple sclerosis (MS). Those people were matched with 395 people with no symptoms of possible MS who were of similar ages, of the same sex and from the same regions of Australia. The differences in sun exposure, vitamin D blood levels, and skin type accounted for a 32 percent increase in a first event.(5) And in a second study that refines the link between sunlight and MS, and looks deeper, it appears that sunlight exposure and a mononucleosis history together explain 72% of the variance in multiple sclerosis incidence within England. Is adequate sunlight--and the resulting healthy blood levels of vitamin D—helping keep this common virus in check, and in ways we do not yet understand, lowering the risk of multiple sclerosis?(6)

These are just a few of the new studies and recommendations on Vitamin D, which we feel reflects a maturing picture and an increasingly nuanced and balanced approach to this potent molecule.

  1. Dawson-Hughes B, Mithal A, Bonjour JP, Boonen S, Burckhardt P, Fuleihan GE, Josse RG, Lips P, Morales-Torres J, Yoshimura N. IOF position statement: vitamin D recommendations for older adults. Osteoporos Int. 2010;21:1151-4. PMID: 20422154
  2. Harvard School of Public Health Nutrition Source.https://www.hsph.harvard.edu/nutritionsource/vitamins/vitamin-d/
  3. Emory-Georgia Tech Center for Health Discovery and Well Beinghttp://shared.web.emory.edu/emory/news/releases/2011/04/vitamin-d-levels-linked-with-health-of-blood-vessels.html
  4. Lucas RM, Ponsonby AL, Dear K, Valery PC, Pender MP, Taylor BV, Kilpatrick TJ, Dwyer T, Coulthard A, Chapman C, van der Mei I, Williams D, McMichael AJ. Sun exposure and vitamin D are independent risk factors for CNS demyelination. Neurology. 2011 Feb 8;76(6):540-8. PMID: 21300969
  5. Ramagopalan SV, Handel AE, Giovannoni G, Rutherford Siegel S, Ebers GC, Chaplin G. Relationship of UV exposure to prevalence of multiple sclerosis in England. Neurology. 2011 Apr 19;76(16):1410-4. PMID: 21502600