Low Vitamin D Linked to Coronary Artery Disease in Blacks With HIV

HIV-positive African Americans with low vitamin D had more than a doubled risk of coronary artery disease in a study of 674 men and women in Baltimore, Maryland.1 Other traditional risk factors also raised the odds of coronary artery disease in these people, including high blood pressure, high low-density lipoprotein (LDL) cholesterol, and cocaine use.

As HIV-positive people live longer thanks to antiretroviral therapy, heart disease -- including coronary artery disease -- has become a more frequent cause of sickness and death. Traditional heart risk factors play a big role in higher heart disease rates among people with HIV. Taking certain antiretrovirals and HIV infection itself have also been linked to a higher risk of heart disease.

Some recent research suggests that low vitamin D levels may raise the risk of coronary artery disease.5 Vitamin D levels are often low in African Americans, partly because dark skin blocks the type of sunlight that helps make vitamin D in the body. Poor diet may also contribute to low vitamin D levels. African Americans have a higher death rate from coronary artery disease than other racial and ethnic groups in the United States.

Researchers in Baltimore planned this study to analyze the impact of vitamin D deficiency (low levels) and other heart risk factors on coronary artery disease in HIVpositive African Americans without known coronary artery disease or physical signs or symptoms of coronary artery disease.

How the Study Worked

The study involved 674 African-American adults in Baltimore who did not have coronary artery disease or symptoms of coronary artery disease. Everyone was 25 years old or older. The study did not include pregnant women or people with poor kidney function indicated by a glomerular filtration rate at or below 60 mL/min/1.73m2.

Study participants were interviewed to determine drug-use behavior, smoking habits, and other factors that may affect risk of coronary artery disease. Researchers measured everyone's lipids (blood fats), blood pressure, and vitamin D levels. Participants underwent computed tomography angiography, a scanning technique that creates a picture of coronary artery narrowing caused by build-up of plaques. The researchers defined significant coronary artery narrowing as 50% or greater narrowing.

The investigators used standard statistical methods to identify factors associated with significant coronary artery narrowing regardless of what other risk factors a person might have.

What the Study Found

The study group included 427 men (63%) and 247 women (37%). Median age was 46 years. Study participants had taken antiretrovirals for a median of 25 months. Median time on protease inhibitors stood at 5.5 months, while few study participants had used nonnucleoside reverse transcriptase inhibitors. The group had a median CD4 count of 329 when the study began.

Median blood pressure stood at 117/73 mm Hg, below a target healthy blood pressure of 120/80 mm Hg. According to the Framingham score, which estimates heart disease risk, 355 of 427 men (83%) and 230 of 247 women (93%) had a low risk of coronary artery disease.

Median vitamin D level in study participants was 17 ng/mL. There were 135 people (20% of the study group) with vitamin D deficiency, defined as a level below 10 ng/mL. Among people whose vitamin D level was above 10 ng/mL, 7.7% had significant coronary artery narrowing. In contrast, 14.9% with a vitamin D level below 10 ng/mL had significant narrowing.

While 5.9% of people taking antiretrovirals for fewer than 6 months had significant coronary artery narrowing, 11.2% of those taking antiretrovirals for more than 6 months had significant narrowing. Rates of significant coronary artery narrowing were 7.7% in those who never used cocaine or used cocaine fewer than 15 years versus 12.5% in those who used cocaine for 15 years or more.

Statistical analysis that considered many coronary artery disease risk factors found seven factors that raised the risk of significant coronary artery narrowing regardless of whatever other risk factors a person had (Figure 1). A vitamin D level below 10 ng/mL more than doubled the odds of significant coronary artery narrowing. Joining the study group in more recent years (after 2005) lowered the risk of significant coronary artery narrowing.

Risk Factors for Coronary Artery Disease in Black With HIV
Figure 1. Low vitamin D levels and other factors shown here independently raised the odds of significant coronary artery narrowing in a study of 674 HIV-positive African Americans. Joining the study group after 2005 lowered the odds of significant coronary artery narrowing (not shown in graph). BP, diastolic blood pressure; LDL, low-density lipoprotein cholesterol; ART, antiretroviral therapy.

What the Results Mean for You

This study found that vitamin D deficiency -- by itself -- raises the odds of significant coronary artery narrowing in African-American men and women with HIV infection.1 Almost 10% of people in this study group had significant coronary artery narrowing (50% or greater narrowing), even though almost 90% of the group had a low heart disease risk determined by a reliable risk score.

Several well-known risk factors also made significant coronary artery narrowing more likely: male gender, high blood pressure, and high "bad" LDL cholesterol. Using cocaine more than 15 years almost doubled the risk of coronary artery narrowing, and taking antiretrovirals for more than 6 months more than doubled the risk of coronary artery narrowing. That last finding does not mean people should stop taking antiretrovirals or delay starting treatment. Numerous studies, including a large randomized trial,6 show that taking antiretrovirals lowers the overall risk of serious heart disease and other non-AIDS diseases.

This study does not prove that low vitamin D levels cause coronary artery narrowing. Low vitamin D may be a signal of other factors that make heart disease more likely, including poverty, poor health care, and poor health habits like smoking. Almost 85% of people in this study smoked cigarettes, and more than 85% drank alcohol.

Because all study participants were African Americans living in a big city, it is unclear whether the findings apply to other groups in the United States or other countries. African Americans and other people with dark skin have a higher risk of low vitamin D because their skin blocks the sun rays that help make vitamin D in the body. However, several other recent studies found high rates of vitamin D deficiency in other HIVpositive groups in the United States and elsewhere.7-10 And these findings add to other evidence suggesting that low vitamin D may raise the risk of coronary artery disease.4,11,12 (See "People with a high risk of low vitamin D" for more information on risk factors.)

People With a High Risk of Low Vitamin D
  • Older adults
  • People with limited sun exposure
  • People with dark skin
  • People who absorb fat poorly
  • People who are obese or who have had gastric bypass surgery
  • Breastfed infants

Source: Office of Dietary Supplements. National Institutes of Health. Dietary supplement factsheet: vitamin D.

Vitamin D is necessary for bone health, for muscle function, and for a healthy immune system.13 Getting as little as 10 minutes of sun exposure daily may help prevent vitamin D deficiency.14 Few foods contain high amounts of vitamin D. Those that do include cod liver oil, swordfish, salmon, tuna, and vitamin D-fortified orange juice, milk, and yoghurt. For a full list of foods rich in vitamin D, use the link at reference 13 below.

The U.S. National Institutes of Health says some people may need vitamin D supplements to maintain healthy levels.13 Your healthcare provider can help determine whether you need vitamin D supplements by measuring your vitamin D level and reviewing your risk for low vitamin D.

For more information on vitamin D, see the National Institutes of Health Fact Sheet linked at reference 15 below. It is also very important for people with HIV to address other heart risk factors like those found in this study (high blood pressure, high LDL cholesterol, and cocaine use) and those established by other research (such as smoking, overweight, obesity, diabetes, and physical inactivity). These are all problems that can be prevented or treated with the help of your HIV provider.

References

  1. Lai H, Gerstenblith G, Fishman EK, et al. Vitamin D deficiency is associated with silent coronary artery disease in cardiovascularly asymptomatic African Americans with HIV infection. Clin Infect Dis. 2012;54:1747-1755.
  2. Camargo CA Jr. Vitamin D and cardiovascular disease: time for large randomized trials. J Am Coll Cardiol. 2011;58:1442-1444.
  3. Lee JH, O'Keefe JH, Bell D, Hensrud DD, Holick MF. Vitamin D deficiency: an important, common, and easily treatable cardiovascular risk factor? J Am Coll Cardiol. 2008;52:1949-1956.
  4. Wang TJ, Pencina MJ, Booth SL, et al. Vitamin D deficiency and risk of cardiovascular disease. Circulation. 2008;117:503-511.
  5. Lai H, Fishman E, Gerstenblith G, et al. Vitamin D deficiency is associated with significant coronary stenoses in asymptomatic African American chronic cocaine users. Int J Cardiol. 2012; 158:211-216.
  6. Strategies for Management of Antiretroviral Therapy (SMART) Study Group, El-Sadr WM, Lundgren JD, Neaton JD, et al. CD4+ count-guided interruption of antiretroviral treatment. N Engl J Med. 2006;355:2283-2296.
  7. Allavena C, Delpierre C, Cuzin L, et al. High frequency of vitamin D deficiency in HIV-infected patients: effects of HIV-related factors and antiretroviral drugs. J Antimicrob Chemother. 2012 May 15. Epub ahead of print.
  8. Adeyemi OM, Agniel D, French AL, et al. Vitamin D deficiency in HIV-infected and HIV-uninfected women in the United States. J Acquir Immune Defic Syndr. 2011;57:197-204.
  9. Cervero M, Agud JL, García-Lacalle C, et al. Prevalence of vitamin D deficiency and its related risk factor in a Spanish cohort of adult HIV-infected patients: effects of antiretroviral therapy. AIDS Res Hum Retroviruses. 2012 Mar 6. Epub ahead of print.
  10. Crutchley RD, Gathe J Jr, Mayberry C, Trieu A, Abughosh S, Garey KW. Risk factors for vitamin D deficiency in HIV-infected patients in the south central United States. AIDS Res Hum Retroviruses. 2012;28:454-459.
  11. Gelfand JM, Cree BA, McElroy J, et al. Vitamin D in African Americans with multiple sclerosis. Neurology. 2011;76:1824-1830.
  12. Kendrick J, Targher G, Smits G, Chonchol M. 25-Hydroxy vitamin D deficiency is independently associated with cardiovascular disease in the Third National Health and Nutrition Examination Survey. Atherosclerosis. 2009;205:255-260.
  13. Office of Dietary Supplements. National Institutes of Health. Dietary supplement fact sheet: vitamin D.
  14. Mayo Clinic Health Information. Vitamin D.
  15. Office of Dietary Supplements. National Institutes of Health. Dietary supplement fact sheet.