Food sources, not supplements, ideal for calcium, vitamin D

Key points to remember:

• Vitamin D and calcium supplements are probably not beneficial for heart health.
• Food sources are the perfect way to increase calcium and vitamin D intake.

PHILADELPHIA — Several studies report associations between low blood vitamin D levels and poorer CV health, but supplements probably aren’t the answer for many patients, according to a speaker.

Similarly, patients who need to increase their calcium intake should watch diet not calcium supplementation, which studies show may even increase CV risk for some, Healio | Member of the editorial board of Cardiology Today Erin D. Michos, MD, MHS, FACC, FAHA, FASE, FASPCassociate professor of medicine and director of women’s cardiovascular health at the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease, said during a presentation at the Heart in Diabetes CME conference.

Clinicians should advise patients to obtain vitamin D through an adequate diet and moderate exposure to sunlight. Consider vitamin D supplementation only if a person is vitamin D insufficient or deficient; however, any effects of supplementation on bone health are likely modest, Michos said.

To improve bone health, patients should also increase physical activity and calcium intake from the diet. Common dietary sources of calcium include yogurt, low-fat milk, and cheeses; non-dairy sources of calcium include white beans, fish, soy, kale, and almonds.

If calcium supplements are being considered, clinicians should incorporate potential CVD risks into the clinician-patient discussion, Michos said. Mega-dosing of any supplement should also be avoided, she noted.

Erin D. Michos

“More is not necessarily better,” Michos said. “You can do too much.”

Vitamin D, biomarker or therapeutic target?

It is estimated that more than one billion people worldwide have insufficient vitamin D levels when using the Endocrine Society criteria of a serum 25-hydroxyvitamin D level below 30 ng/mL, a Michos said, which has implications for bone health. The Institute of Medicine’s recommended daily intake is 600 IU per day of vitamin D and 1,000 IU of calcium per day for adults under 50. About 10 to 15 minutes of maximum sun exposure per day, depending on the season, is equivalent to the vitamin D content of about 30 glasses of milk, Michos said.

Whether vitamin D supplementation improves health is still a hotly debated topic.

“The question is whether the treatment can actually improve outcomes,” Michos said. “There are clearly many studies that suggest that low blood levels of vitamin D are associated with risk of cardiovascular disease and mortality. But is it causal or is it confounding? People with low vitamin D blood levels may be less healthy for other reasons. It could be a marker for someone who is less healthy.

The data so far suggests vitamin D supplementation does not improve health outcomes, Michos said. The big scale VITAL study, one of the largest randomized controlled trials of vitamin D supplementation, showed that vitamin D supplements for primary prevention did not reduce major CV events or the development of invasive cancers compared to placebo over 5 years of followed, although some secondary parameters showed promising signals. A major CV event occurred in 396 patients who received omega-3 fatty acid supplementation versus 409 who received placebo (HR=0.97; 95% CI, 0.85-1.12) and invasive cancer a was diagnosed in 793 patients who received omega-3 fatty acid supplementation versus 824 who received placebo (HR=0.96; 95% CI, 0.88-1.06). Subgroup analyzes in VITAL assessing people with vitamin D deficiency also showed no CV benefit, Michos said.

What’s more, the data “isn’t as strong as you might think” for vitamin D for fracture prevention, Michos said, with many studies showing no benefit for fractures, falls or mortality with supplementation. .

The U.S. Task Force on Preventive Services concludes that current evidence for vitamin D supplementation is “insufficient” to assess the balance between benefits and harms of screening for vitamin D deficiency in asymptomatic adults, and states that more research is needed, Michos said.

Calcium supplements and CVD

Calcium plays an important role in skeletal muscle function, heart and blood vessel contractility, muscle contraction, nerve impulse transmission, coagulation and other body systems. About 40% of American adults report taking calcium supplements, spending more than $1 billion a year, Michos said.

However, clinicians should be careful when discussing calcium supplementation with patients. Unlike vitamin D studies, which were mostly CV neutral, some calcium studies suggest increased CV risk with supplements.

“In randomized clinical trials, there has been a signal of increased risk of coronary events with calcium supplements — not dietary calcium,” Michos said.

Data from the Multiethnic Observational Atherosclerosis Study (MESA) showed that high total calcium intake was associated with a decreased risk of incident atherosclerosis during long-term follow-up, particularly if it was obtained without the use of supplements. However, the use of calcium supplements may increase the risk of incident calcium in the coronary arteries.

“Even the highest quintile of high calcium from the diet was actually associated with a lower [CV] incident coronary calcium risk,” Michos said.

Large bolus doses of calcium have also been shown to transiently increase serum calcium in the body, potentially triggering the coagulation cascade and leading to vascular events, Michos said. In addition to increased vascular calcification, other unintended consequences of too much calcium supplementation can include the development of kidney stones.

“That’s why the diet may be more beneficial,” she said.

The references:

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