This vitamin may protect you from the flu

2026-02-04 07:47:00, Shëndeti CNA

After recent heavy snowstorms, freezing temperatures continue to sweep across much of the United States. The cold, dry, rainy weather could significantly increase flu transmission. More than 15 million flu cases have already been reported as of the start of the 2026 season.

The virus survives longer in low humidity and cold conditions, while rapid weather changes and increased indoor gatherings further increase infection rates. Studies show that flu activity often peaks about a month after colder, drier or wetter, rainier periods.

New research suggests that people with low levels of vitamin D may be more likely to develop severe flu infections. The study, published in The American Journal of Clinical Nutrition, analyzed health data from 36,258 participants in the UK Biobank, a large, long-term research database.

The researchers found that individuals with severe vitamin D deficiency, defined as blood levels of 15 nmol/L, had a 33% higher risk of being hospitalized for a respiratory tract infection compared to those whose vitamin D levels were 75 nmol/L or higher. For every 10 nmol/L increase in vitamin D levels, the risk of hospitalization decreased by 4%.

The Food and Drug Administration of the National Academies of Sciences, Engineering, and Medicine states that vitamin D levels of 50 nmol/L (20 ng/mL) or higher are sufficient for most people, while the risk of deficiency increases at levels below 30 nmol/L (12 ng/mL). To convert nmol/L to ng/mL, divide by 2.5.

Infectious disease experts note that vitamin D plays a role in supporting both innate immunity, the body's first line of defense, and adaptive immunity, which helps the immune system learn to fight specific pathogens.

However, they also point out that the study focused on people with very low vitamin D levels and found an association, not proof of causation, between deficiency and serious infection.

The National Institutes of Health (NIH) recommends a daily intake of vitamin D of 600 IU (15 mcg) for people ages 1 to 70, including pregnant and breastfeeding women, and 800 IU (20 mcg) for adults over age 70. These amounts are designed to maintain healthy blood levels and support overall immune function. For most people, this intake is sufficient to achieve blood levels above 50 nmol/L (20 ng/mL), which is considered sufficient for bone and overall health.

Symptoms of vitamin D deficiency can be subtle and easily overlooked. Common signs include fatigue, frequent infections, muscle weakness, bone or back pain, and mood swings such as depression. In more severe cases, deficiency can contribute to poor wound healing, hair loss, bone loss, or an increased risk of fractures. Anyone concerned about a deficiency should consult a healthcare provider for appropriate testing and guidance.

Vitamin D levels can be increased through sun exposure and diet. Foods rich in vitamin D include cod liver oil, trout, salmon, mushrooms, milk, and fortified cereals. Experts recommend getting a blood test for vitamin D levels before starting supplements, as vitamin D is fat-soluble and can accumulate in the body. Taking too much can increase calcium levels in the blood, leading to health problems.

Dr. Thomas Russo, chief of infectious diseases at the University at Buffalo School of Medicine in New York, says the best flu prevention strategy starts with proven measures.

"The ideal flu prevention program is getting the flu vaccine, yes, even now, because the flu season doesn't end until April or May — and wearing a mask indoors with lots of people," says Russo.

“A vitamin D supplement is one of the things that can help,” he adds. “There’s little harm as long as you don’t overdo it.”/ CNA