Study Finds Link Between Low Vitamin D and Inflammation—Here’s How to Boost Your Levels

• Older people with vitamin D deficiency may have more inflammation in their bodies, according to a new study.
• It's not yet clear whether the lack of vitamin D was causing the additional inflammation, rather, the research simply found an association.
• Supplements or dietary changes can help boost vitamin D levels, though a host of individual factors can determine how much a person might need, experts said.

Older adults who are deficient in vitamin D may be more likely to experience chronic inflammation, new research suggests. 

The study, recently published in PLoS ONE, found an association among a group of older Irish people between low vitamin D levels and high levels of a protein that denotes inflammation in the body.

The link between the two held up even after adjusting for behavioral and lifestyle factors that might otherwise put someone at risk for more inflammation, explained study author Eamon Laird, PhD, a research fellow at the University of Limerick and Trinity College, Dublin.

It’s not yet clear, however, whether low vitamin D levels are driving chronic inflammation. But if researchers find causation, the implications could be significant for helping people avoid dementia, heart disease, cancers, and other chronic diseases as they age.

“As people get older, our immune system goes from a balanced to a more proinflammatory profile. We think this is something called inflammaging,” Laird told Health. “The more chronic inflammation you have over your lifespan, the higher your risk of chronic disease later in life.”

A recent study estimated that 22% of Americans have moderate vitamin D deficiency, and an additional 2.6% have a severe deficiency. Those who are younger, have lower education levels, have lower socioeconomic status, or are non-white are more likely to be deficient.

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Finding an Association Between Vitamin D and Inflammation

The new research builds off of a 2014 study in which Laird and his team found an association between vitamin D deficiency and inflammation in nearly 1,000 adults over the age of 60.

Drawing from the Irish Longitudinal Study on Ageing, the new study includes a broader population—more than 5,300 Irish adults over 50 with an average age of about 63.

Researchers used participant blood samples to measure vitamin D levels and concentrations of C-reactive protein (CRP), an indicator of inflammation.

They then grouped participants based on their vitamin D levels. Concentrations of 50 nanomoles (nmol) per liter (L) or higher were deemed sufficient, while concentrations between 30 and 50 nmol/L were defined as insufficient. Deficiency was defined as a vitamin D concentration of less than 30 nmol/L.

To see the specific connection between inflammation and vitamin D levels in each group, the study authors discounted lifestyle factors that may have played a role—such as obesity, education, disease, and tobacco and alcohol use—in the analysis, Laird said.

“We looked at vitamin D levels and measured inflammation,” he explained. “[People who] were more deficient—[who had] less than 30 nmol/L—had a much higher CRP level, a much higher indication of inflammation.”

This link indicates that raising vitamin D levels could work to control inflammation among older adults with a deficiency.

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How Could Vitamin D Influence Inflammation?

It’s important to note that the study did not find that vitamin D deficiency caused the inflammation that researchers noticed, said Marilyn Tan, MD, chief of the endocrine clinic at Stanford Health Care. 

“Association does not establish causation,” Tan told Health in an email. “It’s possible that the subjects had other chronic medical conditions that were associated with higher [inflammation] levels, and these conditions led to lower vitamin D levels (rather than low vitamin D levels leading to higher CRP).”

Genetics, additional lifestyle factors, or other elements not measured in the study could also explain the link between vitamin D deficiency and inflammation, added Laird.

But there are a few different theories as to how sufficient vitamin D levels may keep inflammation at bay, he explained.

There’s some evidence that vitamin D helps regulate inflammatory cytokines, which are proteins that signal immune cells to fight threats such as viruses and bacteria. They also help decrease the body’s inflammatory response when it’s no longer needed.

“When the vitamin D levels are out of whack, it leads to a bit of immune dysregulation,” said Laird, adding that it’s important to remember that factors such as diet, smoking habits, physical activity levels, and obesity also play a role in inflammation levels.

Having adequate vitamin D levels also has benefits beyond managing inflammation and the immune system.

The vitamin plays a vital role in bone health and regulates calcium and phosphorus balance, Tan said.

However, she noted that despite interest in vitamin D as a health promoter, research hasn’t substantiated links between vitamin D and conditions such as heart disease, cancer, and COVID. In fact, other research “did not show efficacy of vitamin D in preventing fractures, falls, cancer, cardiovascular diseases, type 2 diabetes, asthma, and respiratory infections,” she added.

It would be helpful to have a “randomized controlled trial to see what is the true link between vitamin D and inflammation,” Laird said.

How to Get Enough Vitamin D

The National Institutes of Health (NIH) recommends that people maintain sufficient concentrations of vitamin D to maintain bone and overall health. According to the NIH, people in the U.S. should have at least 50 nmol/L of vitamin (the level deemed “sufficient” in the study).

Although the NIH recommends that people between the ages of 1 and 70 consume 15 micrograms or 600 IU of vitamin D daily, Tan said this may not be sufficient for many people.

“How much vitamin D replacement one needs depends on their baseline levels and other factors such as sun exposure, diet, natural skin color, kidney function, and other health conditions,” she said.

Unfortunately, it’s challenging to determine if a person is deficient or sufficient without a blood test. “There are no real symptoms,” Laird said.

But, added Laird, a person who doesn’t spend much time in the sun or eat enough oily fish or fortified foods may not have sufficient vitamin D levels.

While you can increase vitamin D levels by making foods such as trout, salmon, mushrooms, fortified milk or plant-based milk, and eggs a regular part of your diet, Laird said it’s “very difficult” to get sufficient levels from food alone.

Supplements can be a cheap and effective way to add vitamin D to the body, Laird said. He warned, however, that it’s possible to take too much vitamin D to the point that it becomes toxic (the upper limit is around 375 nmol/L), so he recommended sticking to a low dose—10 to 20 micrograms daily, for example.

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