Vitamin D Deficiency Updated
When a diet lacking in proper nutrients collides with a job that rarely lets you see the sun, vitamin D deficiency can rear its ugly head. Too much time in the sun of course can cause sunburns and raise the risk of skin cancer, but too little and the risk of heart disease skyrockets. Spending some relaxing time out in the sun and eating vitamin-D rich foods such as eggs can work wonders.
Last year we wrote a white paper addressing the increased potential for vitamin D deficiency in shift workers. In it we said that vitamin D has been found to be in short supply in many people. Some studies have found that between 60 and 85% of people are lacking enough vitamin D. Symptoms of vitamin D deficiency can include weak bones resulting in fractures, muscle pain, low energy and fatigue, renal or intestinal problems, depression, mood swings and sleep disorders. Shift workers often have less access to normal sunlight; a main source of vitamin D. In addition, they themselves indicate that their nutritional habits need improvement. So shift workers should make sure they and their health care provider assess which combination of sun, diet or supplements is the best to maximize their vitamin D intake.
This year there have been three additional studies that are relevant to this topic so we decided to take the opportunity to provide an update.
First, researchers from the Harvard School of Public Health have performed an updated review of the medical records and blood samples of 454 men between 40 and 75. These men were selected from 18,225 men who’d participated in the Health Professionals Follow-up Study. This Study began in 1986 for the purpose of evaluating the interactions between men’s nutrition and the incidence of serious illnesses, such as cancer, heart disease, and other vascular diseases. The Study is sponsored by the Harvard School of Public Health and is funded by the National Heart, Lung, and Blood Institute and National Cancer Institute. For more information on the Study overall go to http://www.hsph.harvard.edu/hpfs/.
The men selected for the new analysis had either died from heart disease or suffered a non-fatal heart attack during the first ten years following their enrollment in the study. At the time they enrolled, all the men provided blood samples and completed questionnaires on diet, nutrition and lifestyle factors. The 454 selected for the updated analysis were free of diagnosed cardiovascular disease at their enrollment date.
To conduct the new analysis, the Harvard team compared data relating to these 454 men with data from 900 healthy “control” men with no history of heart disease (Giovannucci E et al. 2008). The analysis showed that after more than ten years of follow up, men with low blood levels of vitamin D were more than twice as likely (i.e., 142 percent more likely) to have died from heart disease or suffered a heart attack, compared with men whose blood levels are considered sufficient, albeit far short of optimal. And even men with intermediate vitamin D levels were 60 percent more likely to have died from heart disease or suffered a heart attack, compared to men with the higher levels.
The data analyzed accounted for factors that could increase heart attack risk (such as family history of heart attack, high blood pressure or diabetes, body mass index, physical activity, cholesterol levels, omega-3 intake). While these results do not prove that higher vitamin D levels produced the risk reduction, the researchers concluded that the amount of vitamin D required for optimal benefit may be higher than would be provided by current recommendations (200-600 IU per day), especially in those with minimal sun exposure.
Another study by researchers at Johns Hopkins University in Baltimore looks to have reaffirmed this earlier study’s findings (Melamed ML et al. 2008). The Johns Hopkins team analyzed a diverse sample of 13,000 initially healthy men and women who’d participated in the National Health and Nutrition Examination Survey (NHANES). This is an ongoing national health survey that obtains information about the health status of individuals residing in the United States. This is a government sponsored survey overseen by the U.S. Department of Health and Human Services. In the past, roughly 50 years,
The Johns Hopkins researchers compared the risk of death between the NHANES participants with the lowest blood levels of vitamin D to those with higher levels from 1993 to 2000. Over the course of almost nine years of follow-up, the researchers documented 1,806 deaths. Nearly 700 of the deaths were associated with some form of heart disease, with 400 of these participants being deficient in vitamin D. Based on this Study, the participants with the lowest levels of vitamin D were more than 25 percent likely to have died over the course of the nine years. Since the number of deaths from heart disease alone was so small, the researchers couldn’t conclude, with statistical certainty that these fatalities resulted solely from low levels of vitamin D. But, it looks like taking the two studies together there is some good evidence that low level of vitamin D results in an increased risk of death.
A third study presented in May at the 2008 American Society of Clinical Oncology annual meeting provides additional evidence that vitamin D may be a key ally against breast cancer (Goodwin PJ et al. 2008). Three years ago, a group of leading American cancer researchers concluded that high levels of vitamin D might help protect against breast cancer (Bertone-Johnson ER et al. 2005). The new study by researchers from the University of Toronto measured vitamin D levels in the blood of 512 newly diagnosed breast cancer patients and tracked the progress of their disease over an average of about 12 years.
Only 24 percent of the women had vitamin D levels deemed adequate. About 38 percent had vitamin D levels low enough to be considered deficient, and 39 percent had levels considered insufficient. The analysis showed that the breast cancer patients with the lowest levels of vitamin D had nearly double the risk of their disease progressing, and were 73 percent more likely to have died within 12 years, compared to women with adequate vitamin D levels. The findings were not affected by factors including age, weight, and tumor stage or grade.
Dr. Goodwin has cautioned that more studies need to be done before firm conclusions about vitamin D and breast cancer can be drawn. So until more is known, Goodwin recommends that her patients not exceed the current recommendations which are 200 IU for women up to age 50, 400 IU for women 51-70, and 600 IU for women 71 and older.
Although these studies are promising, it’s too early to recommend that everyone take vitamin D supplements. However it is wise to get outside in the sun (while using sun protection) and start including more vitamin D-rich foods in your diet. One glass of milk contains 100 IU of vitamin D. Other food source includes fatty fish and egg yolks. Also look for vitamin D fortified-products such as yogurt and breakfast cereals.
©2008workingnights
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Tags: biological clock, chronic problems, circadian rhythms, heart disease, sunlight
