Vitamin D and Cancer

In a previous post from January 27, 2016  (http://blog1.smopinions.com/2016/01/7-interesting-facts-about-vitamin-d.html), it was mentioned that there are associations between vitamin D deficiency and certain types of cancer. This post will explain a little bit more about them.

Regarding colorectal cancer, it was noticed about 2 decades ago, that there is more mortality from colorectal cancer in the northern and northeastern parts of the United States, the ones which receive less sunlight. This in itself is not enough to establish a meaningful association, however, it gave a starting point for research. Then, 2 studies showed that having levels above 30 ng/dL in the blood may reduce the incidence of colorectal cancer by half^1,2.

With respect to breast cancer, a recent study found that postmenopausal women may get a benefit from having adequate vitamin D levels in the blood. The risk of developing breast cancer in this particular group of women was lower than in the same group of women with lower vitamin D in their blood³.

Finally, in regards to prostate cancer, it has been found that this cancer is also more common in regions with less sun exposure. In addition, lower vitamin D levels in the blood are related to more aggressive forms of prostate cancer. Last but not least, adequate levels of vitamin D may aid in the slowing of the progression of this type of cancer⁴.

More research is needed in order to confirm and strengthen these associations. In the mean time, it does not hurt to have adequate levels of vitamin D in the blood, particularly for people living north of the 30th parallel.

References

1. Serum 25-hydroxyvitamin D and colon cancer: eight-year prospective study. Garland CF, Comstock GW, Garland FC, Helsing KJ, Shaw EK, Gorham ED. Lancet. 1989;2(8673):1176-8.

2. Meta-analysis: longitudinal studies of serum vitamin D and colorectal cancer risk. Yin L, Grandi N, Raum E, Haug U, Arndt V, Brenner H. Alim Pharm Therap. 2009 30(2):113-25

3. Plasma vitamin D levels, menopause, and risk of breast cancer: dose-response meta-analysis of prospective studies. Bauer SR, Hankinson SE, Bertone-Johnson ER, Ding EL. Medicine (Baltimore). 2013;92(3):123-31

4. Association between serum 25(OH)D and death from prostate cancer. Tretli S, Hernes E, Berg JP, Hestvik UE, Robsahm TE. Br. J. Cancer 2009;100(3):450-4.

Marco A. Ramos MD

Who is Obese? 5 Dangers of Obesity

The healthcare community has defined obesity as a body mass index (BMI) of 30 or more. The BMI is the ratio between the weight of a person (in kilograms) and the square of the height (in meters). There are many calculators online that can calculate the BMI using pounds and feet/inches. This is a very inexact way of classifying overweight people because there could be very muscular people that could be obese according to this definition. In addition, it may cause shorter people to be overrepresented in the obese population.  In spite of this, the BMI provides an easy way of classifying people according to weight that can lead to meaningful research and can serve as an effective screening tool.

There are many dangers that originate from being obese. I will list here the five most relevant ones

1. Diabetes mellitus. Having excessive adipose tissue causes insulin resistance and some obese people may become diabetic because of this.

2. Hypertension. Obesity is associated with hormonal variations that may lead to salt and water retention and constriction of small arteries. These changes can elevate the blood pressure.

3. Sleep apnea.  This condition is related to obesity. It causes the breathing to stop many times during the night causing problems with oxygenation and getting rid of carbon dioxide.

4. Osteoarthrosis. The extra weight that the obese person has to carry has an impact on the hip and knee joints. This may lead to incapacitating pain and joint replacement surgeries.

5. Cancer. Breast, colon, gallbladder and endometrial malignancies are more common in overweight individuals than in people with normal weight

Diabetes and hypertension are  significant risk factors for coronary artery disease and stroke. Sleep apnea is directly related to hypertension. This means that obesity may impair a person’s health in multiple ways.

Marco A. Ramos MD

7 Interesting Facts About Vitamin D That You Were Probably Not Aware Of

1. Vitamin D is not a vitamin. It is a hormone. it is structurally related to steroids and has intracellular receptors. It does not function as a cofactor in biochemical reactions like vitamins¹.

2. There is a link between vitamin D deficiency and seasonal affective disorder (SAD), a form of depression which happens more often in winter months². 

3. Vitamin D is produced in the the skin (from the interaction with sunlight) and undergoes 2 modifications, one in the liver and another one in the kidney in order to achieve its full effects.

4. There are receptors for vitamin D, almost in every cellular type of the body. Intestines, bones, brain, kidneys are just examples of organs where vitamin D has an effect.

5. Darker skinned people are more vitamin D deficient than lighter skin people. Also, people living north (or south) of the 30th parallel are more deficient than those who do not.

6. There are significant associations between vitamin D deficiency and cancer, specially colorectal, breast and prostate cancers^3,4,5.

7. There is an association between all-cause mortality and low levels of vitamin D⁶.

References

1. Vitamin D: A Hormone for All Seasons - How much is enough? Understanding the New Pressures. Morris H. The Clinical Biochemist Review. 2005; 26(1): 21–32.

2. Association Between Low Serum 25-Hydroxyvitamin D and Depression in a Large Sample of Healthy Adults: The Cooper Center Longitudinal Study. Hoang, MinhTu T. et al. Mayo Clinic Proceedings. 2011;86(11): 1050-1055

3. Association between vitamin D and risk of colorectal cancer: a systematic review of prospective studies. Ma Y, Zhang P, Wang F, et al. Journal of Clinical Oncology. 2011;29(28): 3775-3782.

4. Vitamin D Deficiency Predicts Prostate Biopsy Outcomes. Murphy AB. Clinical Cancer Research. 2014;20(9): 2289–2299.

5. Vitamin D and Reduced Risk of Breast Cancer: A Population-Based Case-Control Study. Knight JA et al. Cancer Epidemiology Biomarkers Prevention. 2007;16(3):422–429

6. Meta-analysis of All-Cause Mortality According to Serum 25-Hydroxyvitamin D. Garland CF et al. American Journal of Public Health. 2014;104(8): e43-e50.

Marco A. Ramos MD