Fungi are microorganisms that include many different species, such as mushrooms, yeasts, mildews, and molds. They’re found in almost all environments, including the outdoors (e.g., soil, trees, plants), indoors (e.g., air, household surfaces), and even on and inside people (e.g., toenail fungus, yeast infections).

Some fungi are harmless — think edible mushrooms, which are delicious and nutritious — while others can lead to illness or even death, such as Candida or Aspergillus.

We know that environment and exposure to harmful fungi play a role in fungal sickness, but it’s now believed that lifestyle and diet may play a role, too. In particular, researchers are looking into whether vitamin deficiencies can cause fungal infections.

This article tells you about the current research on vitamin deficiencies and their potential roles in fungal infections.

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Fungal infections can happen to anyone, but they’re especially common in people with compromised immune systems.

Common fungal infections involve nail or skin infections like athlete’s foot and yeast infections (e.g., Candidiasis of the skin, throat, gut, or vagina).

While these infections are usually a low risk for most people and can be treated easily, they can become serious threats to people with compromised immune systems — known as opportunistic infections or opportunistic fungi.

Examples of people who may have weakened immune systems include:

  • pregnant people
  • children and babies
  • older adults
  • those living with autoimmune conditions, such as Crohn’s disease, celiac disease, arthritis, type 1 diabetes, and lupus
  • those living with cancer, HIV, or other immunodeficiencies
  • those living with chronic diseases like type 2 diabetes, heart disease, kidney disease, and obesity
  • people taking immunosuppressants, such as transplant recipients

Nutrient deficiencies can also weaken your immune system, which could potentially increase your risk of developing more severe fungal infections.

To date, little research shows a clear connection between vitamin deficiencies and fungal infections.

There are some small test-tube, animal, and human studies suggesting that certain vitamins, such as B vitamins and vitamin D, may have antifungal effects.

In a 2017 study, mice with vaginal candidiasis were given an oral vitamin B complex, along with a suppository and vaginal cream. They had significantly greater improvements in symptoms compared with those who received the medical treatment but no B vitamins.

While interesting, there’s no research on B vitamin deficiencies and the incidence of candidiasis or other fungal infections in humans. Further research will be needed to learn more.

In a 2019 study on critically ill children taking broad-spectrum antibiotics, researchers found that consuming a yogurt drink with 300 IU of vitamin D resulted in significantly fewer Candida infections compared with the group who consumed the yogurt drink but did not take vitamin D.

Considering that vitamin D deficiency is common in people with critical illness and may also be linked to a greater risk of Candida infections, the authors concluded that vitamin D in conjunction with other standard fungal treatments may reduce the incidence of fungal infections.

It’s important to note that both groups had borderline low (but still within the normal range) vitamin D levels. Thus, research on those with moderate to severe vitamin D deficiency is still needed.

A research review in 2017 also found that a vitamin D deficiency may weaken the body’s immune response, making it more likely to develop infections, including fungal infections.

But the authors cautioned that more research is needed to understand the association between vitamin D deficiency and the incidence of fungal infections.

To date, some research — albeit limited — suggests that vitamin deficiencies may play a role in a weakened immune response, which could increase a person’s risk and severity of fungal infections.

However, it does not appear that having a vitamin deficiency would directly cause a fungal infection.

Due to the limited research available on the topic, it’s unknown if certain vitamin treatments would be effective in treating fungal infections.

However, correcting a vitamin deficiency is important for supporting a healthy immune system and may lower your risk of severe infections.

Further, some nutrients may support a healthy immune system, such as B vitamins, vitamins A, C, D, and E, zinc, iron, selenium, and protein. Often, you can get these nutrients through food alone, but some people may benefit from supplements.

If you think you might have a vitamin deficiency, it’s important to reach out to a doctor so they can order proper bloodwork. Always check in with a healthcare professional before starting any new supplements.

Often, fungal infections are caused by:

  • contact with a fungus from another human or surface, as is the case with athlete’s foot, nail fungus from nail salons, or ringworm
  • skin that’s exposed to warm and moist environments like sweaty gym clothes or shoes, or going barefoot in changing rooms, steam rooms, or swimming areas
  • poor oral hygiene, which can lead to thrush
  • weakened immune systems (e.g., exposure to certain fungi such as Aspergillus, invasive Candidiasis, Pneumocystis jirovecii that causes pneumonia)
  • exposure to fungi via travel, contact with the environment or animals, etc.
  • hormonal changes like alterations to vaginal pH, which can lead to yeast infections

If you think you might have a fungal infection, it’s important to take care of it right away. Some infections can worsen over time and be contagious.

Fungal infections can happen to anyone, but they’re often most dangerous for people with compromised immune systems.

To date, there’s no evidence that vitamin deficiencies directly cause a fungal infection. But some research does suggest that vitamin deficiencies may weaken your immune system, thus making you more likely to develop an infection.

Therefore, correcting any vitamin deficiencies is important, especially if you already have a weaker immune system or have a higher likelihood of developing infections.

If you think you might have a fungal infection, reach out to a healthcare professional as soon as possible to prevent it from worsening.