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Vitamin D for Hypertension

Narinder Duggal, MD, FRCPC

Hypertension is one of the most important modifiable risk factors for cardiovascular disease (CVD).^1,2 This article will help you understand the available scientific evidence on how vitamin D sufficiency may help decrease your risk of developing hypertension, further decreasing the risk of cardiovascular events. A 1997 paper by Dr. Rostand  revealed a very interesting fact; the prevalence of hypertension increases in populations as we move away from the equator.³ Similarly, blood pressure is higher in winter than summer. Blood pressure is also affected by variations in skin pigmentation. Within the same geographic area of North America and Europe, people with dark color were found to have higher blood pressure compared to people with lighter skin.

Traditionally, these differences have been associated with several variables.  Dietary variation, particularly sodium and potassium consumption,^4,5 intrinsic racial differences in renal hemodynamics and sodium metabolism,^6-9and  social and economic stresses of industrialization¹⁰ have been indicated as causative factors. However, the difference in vitamin D levels of the populations in different geographic areas should be considered. Reduced formation of vitamin D3 in the skin due to high skin melanin content in darker colored persons and/or decreased UV light intensity at distances away from the equator may explain this observation. This decrease in  vitamin D levels is further augmented with insufficient dietary vitamin D intake.

Vitamin D insufficiency/deficiency leads to increased parathyroid hormone levels which is thought to stimulate the growth of vascular smooth muscle and its contractility to stress referred to as adrenergic responsiveness, and contributing to development of hypertension. Additionally, Vitamin D deficiency activates the renin-angiotensin-aldosterone system, the hormone system that regulates blood pressure and fluid balance, which can lead to hypertension and left ventricular hypertrophy (abnormal thickening of heart muscles).

In the 2008 Framingham Offspring Study, Wang et al studied 1739 participants for over 5 years and found that people with low vitamin D levels and high blood pressure were at a stunning  113 percent increased risk of cardiovascular events when compared to those with normal blood pressure and healthy vitamin D levels.¹¹ Wang reported that their data increases the likelihood that treating vitamin D deficiency, via supplementation or lifestyle measures, could reduce cardiovascular risk.

Scragg et al (2007) and Judd et al (2008) evaluated approximately 13000 subjects of the Third National Health and Nutrition Examination Survey (NHANES III) and found an inverse association between serum 25(OH)vitamin D concentration and blood pressure in non-hypertensive subjects after adjusting for age, gender, ethnicity, and physical activity.^{12 13} Similarly, Martins et al (2008) looked at the association between serum 25(OH)vitamin D and several cardiovascular disease risk factors and found 25(OH)vitamin D levels to be significantly lower in hypertensive patients as well as in participants with obesity and diabetes mellitus.¹⁴

While all the above studies were retrospective studies, Forman and his colleagues (2007) organized two prospective cohort studies including 613 men from the Health Professionals' Follow-Up Study.¹⁵ During 4 years of follow-up, the multivariable risk analysis found that vitamin D deficient men (<15 ng/mL) were over 6 times more likely to develop hypertension compared with those whose levels were at least 30 ng/mL.

Hypertension  is a rapidly growing health problem that is expected to affect 1.6 billion people worldwide by the year 2025.¹⁶ While lifestyle modifications including losing weight, exercising and dieting to maintain the recommended BMI of less than 25 kg/m² may be the foremost goal in your effort to decrease your risk of hypertension, maintaining optimal vitamin D levels could be a significant additional dietary factor in maintaining a healthy blood pressure. Optimal Vitamin D levels are important to our overall physical and mental health. As it may not be possible to spend sufficient amounts of time in the sun to allow endogenous production of vitamin D, Vitamin D10 supplementation from Synergy Therapeutics RX is a logical solution to ensure optimal levels.


References:

1.    http://www.cdc.gov/nchs/data/databriefs/db03.pdf. (Open link)
2.    Lewington S, Clarke R, Qizilbash N, et al. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet 2002;360(9349):1903-13. (PUBMED Abstract)
3.    Rostand SG. Ultraviolet light may contribute to geographic and racial blood pressure differences. Hypertension 1997;30(2 Pt 1):150-6. (PUBMED Abstract)
4.    Weinberger MH. Salt sensitivity of blood pressure in humans. Hypertension 1996;27(3 Pt 2):481-90. (PUBMED Abstract)
5.    Tobian L. The Volhard lecture. Potassium and sodium in hypertension. J Hypertens Suppl 1988;6(4):S12-24. (PUBMED Abstract)
6.    Campese VM, Parise M, Karubian F, Bigazzi R. Abnormal renal hemodynamics in black salt-sensitive patients with hypertension. Hypertension 1991;18(6):805-12. (PUBMED Abstract)
7.    Frohlich ED. Hemodynamic differences between black patients and white patients with essential hypertension. State of the art lecture. Hypertension 1990;15(6 Pt 2):675-80. (PUBMED Abstract)
8.    Luft FC, Grim CE, Fineberg N, Weinberger MC. Effects of volume expansion and contraction in normotensive whites, blacks, and subjects of different ages. Circulation 1979;59(4):643-50. (PUBMED Abstract)
9.    Luft FC, Weinberger MH, Grim CE. Sodium sensitivity and resistance in normotensive humans. Am J Med 1982;72(5):726-36. (PUBMED Abstract)
10.    Anderson NB, Myers HF, Pickering T, Jackson JS. Hypertension in blacks: psychosocial and biological perspectives. J Hypertens 1989;7(3):161-72. (PUBMED Abstract)
11.    Wang TJ, Pencina MJ, Booth SL, et al. Vitamin D deficiency and risk of cardiovascular disease. Circulation 2008;117(4):503-11. (PUBMED Abstract)
12.    Judd SE, Tangpricha V. Vitamin D deficiency and risk for cardiovascular disease. Am J Med Sci 2009;338(1):40-4. (PUBMED Abstract)
13.    Scragg R, Sowers M, Bell C. Serum 25-hydroxyvitamin D, ethnicity, and blood pressure in the Third National Health and Nutrition Examination Survey. Am J Hypertens 2007;20(7):713-9. (PUBMED Abstract)
14.    Martins D, Wolf M, Pan D, et al. Prevalence of cardiovascular risk factors and the serum levels of 25-hydroxyvitamin D in the United States: data from the Third National Health and Nutrition Examination Survey. Arch Intern Med 2007;167(11):1159-65. (PUBMED Abstract)
15.    Forman JP, Giovannucci E, Holmes MD, et al. Plasma 25-hydroxyvitamin D levels and risk of incident hypertension. Hypertension 2007;49(5):1063-9. (PUBMED Abstract)
16.    Martini LA, Wood RJ. Vitamin D and blood pressure connection: update on epidemiologic, clinical, and mechanistic evidence. Nutr Rev 2008;66(5):291-7. (PUBMED Abstract)