In a new study, researchers find higher levels of vitamin D are associated with decreasing risk of breast cancer.
The study is published in PLOS ONE.
The scientists pooled data from two randomized clinical trials with 3,325 combined participants and a prospective study involving 1,713 participants to examine the association between risk of female breast cancer and blood vitamin D concentrations.
All women were age 55 or older. The average age was 63. Data were collected between 2002 and 2017.
Participants were free of cancer at enrollment and were followed for a mean period of four years. Vitamin D levels in blood were measured during study visits.
Over the study, 77 new cases of breast cancer were diagnosed for an age-adjusted incidence rate of 512 cases per 100,000 person-years.
Researchers identified the minimum healthy vitamin D level is 60 ng/ml, substantially higher than the 20 ng/ml recommended in 2010.
Some groups have advocated higher minimums for health blood serum levels of vitamin D, as much as 50 ng/ml. The matter remains hotly debated.
“We found that participants with blood levels of vitamin D that were above 60 ng/ml had one-fifth the risk of breast cancer compared to those with less than 20 ng/ml,” said the authors.
Risk of cancer appeared to decline with greater levels of serum vitamin D.
Researchers said the study builds upon previous epidemiological research linking vitamin D deficiency to a higher risk of breast cancer.
Epidemiological studies analyze the distribution and determinants of health and disease, but it has been argued that they do not necessarily prove cause-and-effect.
“This study was limited to postmenopausal breast cancer. Further research is needed on whether high vitamin D levels might prevent premenopausal breast cancer,” one author said.
The population was also mainly white women so further research is needed on other ethnic groups.
“Nonetheless, this paper reports the strongest association yet between serum vitamin D and reduction in risk of breast cancer,” he said.
To reach a healthy level of vitamin D, people would generally require dietary supplements of 4,000 to 6,000 international units (IU) per day, less with the addition of moderate daily sun exposure (approximately 10-15 minutes per day outdoors at noon).
The success of oral supplementation should be determined using a blood test, preferably during winter months.
The current recommended average daily amount of vitamin D3 is 400 IU for children up to one year; 600 IU for ages one to 70 years (including pregnant or breastfeeding women) and 800 IU for persons over age 70, according to the National Academy of Medicine.
News source: UCSD. The content is edited for length and style purposes.
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