Increasing calcium intake at breakfast and lowering it at dinner was linked to a reduction in cardiovascular risk.
- A
new study of more than 36,000 American adults suggests that too much
dietary calcium intake in evening meals could lead to a higher risk of
cardiovascular disease.
- Experts
say that circadian rhythms help regulate the absorption of calcium, and
daylight hours are generally the best for that process.
- But
too much calcium in general, especially from supplements, can lead to
issues that contribute to cardiovascular problems.
Reducing the intake of
dietary calcium at dinner and instead increasing
it at breakfast could lead to a reduced risk of cardiovascular
disease, a new study suggests.
The study, published in
The study participants were
17,456 males, 18,708 females, and 4,040 cardiovascular disease patients; their
calcium intake from morning and evening meals was divided into five different
quadrants.
Excluded from the study
were people under 20 years old, pregnant women, anyone using calcium
supplements, people who consumed more than 4,500 kilocalories (kcal) a day, and
those with incomplete data.
Ultimately, researchers found, spreading the intake
of calcium over the two meals was the best for reducing the risk of
cardiovascular disease. But substituting a 5% calcium intake from dinner with
that at breakfast pulled that risk down 6% overall.
Still, the authors write,
there are other factors that are either unobserved or unknown that could affect
the ultimate results, and that cohorts of other races and countries need to be
examined for any discrepancies or similarities.
“Currently, the evidence
for the relationship between dietary calcium intake and [cardiovascular
disease] risk is insufficient and controversial,” the study authors wrote, while
noting that this was the first such study to examine the links between calcium
consumption at breakfast/dinner and cardiovascular disease.
“Studies have shown that
too much or too little calcium intake has adverse effects on [cardiovascular
disease],” they noted in their paper.
How does
calcium interact with the cardiovascular system?
Calcium’s
role in the body is most notably in the formation and maintenance of bones and
teeth, but it also regulates muscle contraction, helps with blood clotting, and
maintains the muscle processes of the heart.
Cardiovascular disease is
known to be the
Where calcium and cardiovascular disease intersect may
have to do with circadian rhythms, which can also affect the way that nutrients
are absorbed in the body.
As the current study
authors noted in their paper, recently: “[S]ome studies have demonstrated that
the circadian clock system can interact with nutrients to influence bodily
function. In mammals, circadian oscillations in physiology and behavior are
controlled by a master clock located in the suprachiasmatic nucleus of the
hypothalamus.”
Some researchers also
believe that these internal rhythms can regulate the absorption of calcium and
metabolism.
Melanie
Murphy Richter, a registered dietitian nutritionist and the director
of communications for the nutrition company Prolon, who was not involved in the
study, told Medical
News Today that circadian rhythms make a big difference:
“From a circadian pattern
perspective, research suggests that calcium absorption might be slightly higher
during the day because certain hormones that are required for calcium
metabolism like the parathyroid hormone, for instance, tend to also be higher
during daylight hours.”
Richter added that overuse
of calcium supplements in general can also be problematic, given that dietary
calcium can be difficult to consume too much of by itself.
“Most of the issues
relating to calcium intake and cardiovascular health are related to
supplementation, where toxic overloads are more easily achieved. Taking too
much calcium can result in a condition called hypercalcemia,” she said.
“Hypercalcemia can contribute to heart arrhythmias,
heart palpitations, fainting, and sometimes even more severe heart issues.
Additionally, high calcium intake can contribute to the formation of calcium
deposits in our arteries which can decrease blood flow and therefore increase
incidents of stroke, hypertension or heart attack,“ explained Richter.
“Not to mention, excessive
calcium supplementation can increase vascular inflammation and oxidative stress
which can impact the development of more problematic cardiovascular diseases,”
she added.
Who should
take calcium supplements?
Kristin
Kirkpatrick, a registered dietitian at the Cleveland Clinic
Department of Wellness & Preventive Medicine in Cleveland, OH, and a senior
fellow at the Meadows Behavioral Healthcare in Wickenburg, Arizona, who was
also not involved in the study, told MNT that the decision to take a supplement — and
which one to take — all depends on a person’s specific needs.
“Since calcium has other risk factors seen previously
in studies, and since the different types of calcium — for example, citrate vs.
carbonate — act differently in the body and have varying
“I encourage all my
patients to discuss the pros and cons of calcium with their physician first.
Not all calcium supplements are equal – I encourage my patients to check the
latest data and independent lab analyses of certain calcium supplements,” she
told us.
Richter said that
supplementation depends on a lot of factors — age, genetics, overall health —
but that a balanced, healthy diet may eliminate the need to do so.
“Older individuals,
especially peri-menopausal women, for instance, are at higher need of calcium
due to the reduction of estrogen production in the body which can decrease
calcium absorption. To prevent bone loss and diseases like osteoporosis, it is
wise to supplement with calcium and increase calcium-rich foods in the diet,”
she noted.
“Anyone who eats a high
processed foods diet low in leafy greens, nuts, and seeds are also going to be
at higher risk for calcium deficiency, in which case, supplementation might be
beneficial. Anyone who is lactose intolerant and needs to avoid dairy (a high
calcium food) but isn’t also mindful of replacing their foods with vegetables
and seeds may be at higher risk for low calcium levels. Overall, however, if
you are eating a balanced diet rich in plants, nuts, seeds, and occasional
dairy or fortified dairy alternatives, you likely do not need to supplement.”–
Melanie Murphy Richter
Is there an optimal way
to take calcium supplements?
Kirkpatrick
said that the way the body responds to calcium warrants smaller portions.
“Given that vitamin D
enhances calcium absorption, there is a case for taking calcium in the morning.
This allows for exposure to vitamin D throughout the day, primarily through
sunlight,” Kirkpatrick noted.
“However, another approach is to divide the calcium
dose into smaller portions taken with meals. This is beneficial because the
body can only absorb a limited amount of calcium at a time,” she explained.
Richter added that certain
supplements also have combinations of other elements that can be beneficial.
“Calcium supplements can be
combined with magnesium, vitamin D, and zinc. In fact, all three of these
additional nutrients can enhance bone support by increasing calcium
absorption,” Richter said.
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