Jenny McCarthy says going vegan nearly killed her: What to know about the popular diet

"The Masked Singer" judge Jenny McCarthy recently said she "almost died" after trying a vegan diet. The 52-year-old actress, television personality and wife of actor Donnie Wahlberg shared on the "Heal Squad" podcast that she became very ill after following the popular diet.

"I tried vegan and I almost died. I literally almost died," McCarthy told podcast host Maria Menounos.

The vegan diet eliminates all animal products, including meat, eggs, seafood, poultry, dairy products, honey, eggs and other animal derivatives like gelatin. 

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The diet consists mainly of vegetables, fruits, whole grains, legumes, nuts and seeds, according to Jamie Mok, a Los Angeles-based registered dietitian and spokesperson for the Academy of Nutrition and Dietetics.

"Research indicates that a well-balanced vegan diet can offer numerous health benefits, such as reducing the risk of chronic diseases like heart disease, cancer and diabetes," Mok told Fox News Digital.

Jenny McCarthy said she "almost died" after trying a vegan diet. (Gilbert Flores/Billboard via Getty Images)

There are potential downsides to this diet, however, that need to be discussed with a registered dietitian or physician before someone "goes vegan," especially if the person has certain medical conditions or food allergies, nutrition experts told Fox News Digital. 

"A poorly planned vegan diet can lead to deficiencies in essential nutrients like vitamin B12, vitamin D, calcium, iron, omega-3 fatty acids, iodine and protein, potentially resulting in conditions like anemia and osteoporosis," Mok said.

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In McCarthy's case, the vegan diet did not agree with her food allergies (soy) and an underlying medical condition called celiac disease — meaning her body does not tolerate gluten. She said she was unable to get enough nutrients while following a vegan diet plan.

"The vegan diet was the cherry on top – the perfect storm for malnutrition/nutritional deficiencies, in my opinion," Deborah Salvatore, a registered dietitian and director of graduate nutrition programs at Long Island University in Brookville, New York, told Fox News Digital.

Jenny McCarthy's food allergies combined with celiac disease adversely impacted her vegan diet, a food expert told Fox News Digital. (Jeff Kravitz/FilmMagic; iStock)

Salvatore has an extensive background in celiac disease but was not involved in McCarthy's case. She said it was likely that "her body was under a continuous immune response that was damaging her small intestine, which led to decreased surface area within the small intestine, causing malabsorption of both macro- and micronutrients."

A vegan diet can be a "healthful and realistic diet," Salvatore said — but individuals need to be vigilant that the body's nutritional needs are being met.

Those making drastic diet changes need to monitor their body for reactions, experts say.

"When we pair veganism with a gluten-free diet, we must exchange the whole-grain products with gluten-free whole grains like amaranth, buckwheat, gluten-free oats, millet, brown rice and quinoa," Salvatore said.

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Nutrition experts also said that anyone making drastic diet changes needs to monitor their body for reactions.

"Persistent fatigue, weakness or muscle loss, hair thinning, brittle nails, mood changes, digestive issues, frequent illnesses, skin problems, unintended weight fluctuations and intense cravings can all signal that your diet might require adjustments," Mok told Fox News Digital. 

Gluten-free options for vegans include whole grains, flours, pasta and bread. (iStock)

Although a vegan diet has fewer saturated fats, a meat-based diet also has benefits, said Laura Feldman, a registered dietitian and director of the undergraduate Didactic Program in Dietetics at Long Island University.

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"Animal foods such as meat, dairy, eggs and fish are an excellent way to get essential nutrients such as protein, iron, calcium and zinc," Feldman told Fox News Digital. 

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"Often, a person would have to eat a larger portion of food to get the same amount of many of these nutrients from plant-based sources."

When it comes to deciding if you should follow a restrictive diet of any kind, it is best to do so under the guidance of a healthcare professional, several dietitians told Fox News Digital.

Steak and eggs are "an excellent way" to get essential nutrients like protein, a dietitian told Fox News Digital. (iStock)

"Jenny's story demonstrates the challenges many Americans face due to food allergies and food sensitivities," said Vanessa King, a registered dietitian nutritionist in Hawaii.

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To help ensure adequate nutrition, registered dietitian nutritionists can help with meal planning, finding food substitutes and label reading, said King.