A cardiologist takes 3 supplements every day that can help prevent fatigue and boost immune function

• Danielle Belardo has spent decades studying heart health.
• She takes three supplements regularly: folic acid, vitamin B12, and vitamin D.

Danielle Belardo has dedicated her career to studying the heart, and helping her patients and the general public live healthier lives.

A cardiologist based out of Los Angeles, Belardo sees patients and also hosts a podcast educating the public on how to reduce the risk of cardiovascular disease and debunking wellness trends.

One question people frequently ask her, Belardo said, is about supplements. People want to know if they should be taking supplements, and if so, what type.

While Belardo said that most supplements aren't necessary unless you have a deficiency, there are a few that can be helpful depending on your specific circumstances, like where you live and your personal diet.

Here are the three that Belardo herself takes every day.

Folic acid

Folic acid is the synthetic form of folate or vitamin B9.

It is recommended for all women of child bearing age, Belardo said. Belardo, who is in her 30s, said she takes a multivitamin that has folic acid every day.

The U.S. Centers for Disease Control and Prevention recommends that women consume 400 micrograms of folic acid daily.

Although most people get enough folate through their diet, the CDC recommends that anyone who is capable of becoming pregnant take folic acid, because about half of pregnancies in the US are unplanned and folic acid can prevent major birth defects.

Vitamin B12

Belardo is a vegan, a diet that is considered healthy for your heart. And for many vegans, vitamin B12 can be hard to come by because it is naturally found in foods like meat, dairy, eggs, and fish — but not plants.

It's still necessary to get vitamin B12, however, because it is essential in the formation of red blood cells and DNA.

Vegans and vegetarians are at greater risk of vitamin B12 deficiency, which can lead to symptoms like pins and needles in your hands and feet and feeling very tired.

Although vegans and vegetarians can get B12 through fortified foods, like milk and cereal, ensuring that you're meeting the small but necessary daily dose of 2.4 micrograms "may take a lot of planning," Belardo said.

As a result, she said she recommends that "anyone that is exclusively plant based either vegan or vegetarian just supplement with B12 just to be safe."

Vitamin D

Like biohacker Bryan Johnson and immunologist Dr. Anthony Fauci, Belardo also takes a vitamin D supplement.

Vitamin D helps with calcium absorption, and may also help prevent muscle cramps, reduce inflammation, and improve immune function.

Like vitamin B12, it can be tricky for vegans to get Vitamin D through diet alone, Belardo said, "since it is found in significant amounts primarily in animal products."

Your environment and genetics might put you at risk of a vitamin D deficiency too, Belardo said. "Vitamin D depends on where you live, how much sun exposure you have, and different genetic factors, and how much of fortified foods you're eating with vitamin D as well."

While sun exposure can increase your vitamin D levels, Belardo notes that the American Academy of Dermatology does not recommend sun exposure because it can increase risk of skin cancer. "I take a vitamin D supplement because I avoid getting sunburned at all costs," Belardo said.

Before taking any of these supplements, Belardo said that it's important to talk with a doctor to determine the proper dose and frequency of a supplement to meet your individual health needs.

That's because medical professionals don't broadly recommend supplements unless there's a specific need for one. And if you do have a deficiency, Belardo said, "that is a problem that needs to be investigated."