Newton, entering his 10th NFL season and first as the Patriots’ starting quarterback, said he has seen a “remarkable change” in the way his body has responded to his vegan diet.

“God has given me this body and this talent, but at the same time, I have to recover, and staying hydrated and things like that,” said Newton, 31, who was the face of PETA’s “Built like a Vegan” campaign in July. “So [I’m] not trying to eat foods that will inflame my joints. You cannot eat enough green veggies.”

But injuries have mounted the last two years, and Newton is now at a career crossroads, playing on a one-year, minimum-salary contract. There are questions about whether his vegan diet and slimmed-down physique have done him more harm than good.

Newton is hardly unique in adopting a plant-based diet. Tom Brady, Aaron Rodgers, Russell Wilson, Marcus Mariota, Matthew Stafford, Andrew Luck, and Colin Kaepernick are just some of the quarterbacks who have gone vegan or near-vegan in recent years.

The difference is that a big part of Newton’s game is his physical dominance. Newton, listed at 6 feet 5 inches and 245 pounds, takes and delivers a lot of hits.

Newton has averaged 7.5 carries per game over his career, the most in NFL history by a quarterback. His game is running through 230-pound linebackers, and bouncing back up when pass rushers flatten him in the pocket. Over the last decade, no quarterback has taken more hits than Newton, and it’s not close.

Some nutrition experts say that by cutting out all animal products — eggs and dairy in addition to meat — it can be challenging for Newton to consume the protein and amino acids needed for injury recovery. Newton had a slow recovery from shoulder surgery in the spring of 2019, then missed 14 games last fall with a foot injury. The Panthers released him in March.

“I have never once recommended an athlete of mine change over to a vegan diet,” said Laura Moretti, a registered sports dietician with offices in Somerville and Newton. “When we’re looking at the gold standard for recovery, we’re always coming back to those essential amino acids. We’re getting all nine of those in animal-based foods. For an athlete like Cam to keep up with his needs, I would think it is hard to do on a vegan diet.”

Newton’s combination of size and speed has been a major weapon. He has 4,806 rushing yards in his career, third-most of any QB in NFL history, with 1,621 of them (33.7 percent) coming after first contact.

Though listed at 245 pounds since entering the NFL in 2011, Newton actually played in the 260-265-pound range.

Former Panthers teammate Roman Harper remembered a 2-yard touchdown run by Newton in 2015 in which he fought through five Titans defenders.

“They hit him at the 1- or 2-yard line, and he just kept stretching it and stretching it until it was a touchdown,” Harper said. “How many other quarterbacks can do that?”

But 934 rushing attempts, 291 sacks, and hundreds of other hits over nine NFL seasons have begun to take their toll. A 2016 ESPN study found that Newton took more than 10 hits per game over his career, which was about 20 percent more than any other quarterback in the league during the same time period. Newton suffered a concussion in 2016, a shoulder injury in 2018, then a foot injury in 2019.

So Newton decided he was going to cut weight. In 2017, he said he reached his listed weight of 245 pounds for the first time. In 2019 training camp, he said his goal was 235-238 pounds.

“During the offseason, honestly, I really try to get as small as I can,” Newton said last year.

Staying lean and reducing inflammation with a plant-based diet has helped Brady stay on top of the NFL into his 40s. But it may not be the right answer for Newton.

“I don’t think he is Superman anymore,” an anonymous NFL coach told The Athletic this summer. “Remember when Kaepernick became vegan, changed his body, and he just wasn’t as dynamic of an athlete anymore? Cam was 265 and bigger than everybody. He looks skinny now, like he is 235 and wants to have ripped abs, and that’s his choice. Is he going to have that power running element?”

Coming off his second straight injury-marred season, Newton himself doesn’t know how his body will hold up this year.

“We’re just going to have to see,” he said. “Nothing that I say right now would make sense until we see it.”

His Patriots coaches are going to treat Newton like the player of old until he proves otherwise.

“You have to assume that he’s healthy Cam, which is what we’ve seen since we started working with him,” quarterbacks coach Jedd Fisch said. “That’s the assumption we are going to work off of until he’s unable to do the things he has shown he’s able to do.”

In a video last year, Newton and comedian Hannibal Buress went to a vegan restaurant for barbecue jackfruit carnitas tacos and fried cauliflower in a cashew cheese sauce.

“I don’t want people to think that you can’t love food being vegan or there’s not good-tasting food that’s vegan,” Newton said. “I feel good. I recover well. And that’s pretty much what it’s all about.”

A vegan diet can certainly be healthy and fulfilling. The problem with cutting out all animal-sourced foods, however, is it becomes tougher for an athlete to consume the calories, protein, and amino acids he needs to fuel his body and recover.

“There’s nothing magical about a vegan diet. It’s an excellent diet,” said Boston-area sports nutritionist Nancy Clark, who has worked with the Celtics and Red Sox. “But performance is really based on getting all the nutrients, so you can’t say a vegan athlete will perform better than someone who is eating a different diet.”

Cutting out meat and dairy can lead to deficiencies in B12, which affects energy levels; in iron, which delivers oxygen to your muscles; and in leucine, the amino acid connected to muscle-building.

These deficiencies can lead to increased fatigue, decreased endurance, and longer recovery times. Vegan athletes usually have to take several vitamin supplements.

“When someone is eating animal protein, they’re able to obtain all nine essential amino acids, whereas vegetarian or vegan protein sources might contain seven of them, but not all of them,” said Moretti, who is also the sports dietician at Boston Children’s Hospital. “It’s a very labor-intensive diet. I usually caution people, more about going on it, because of the amount of planning and the amount of risk for these deficiencies.”

Newton certainly has the means and resources to execute a carefully curated diet of vegan food and supplements. But another issue is simple calorie ingestion. It is a lot harder for someone of Newton’s size to get enough calories in a day from eating beans, lentils, and vegetables.

Hall of Fame tight end Tony Gonzalez went vegan in 2007, immediately lost 10 pounds, and found himself significantly weaker in the weight room. He decided the vegan diet wasn’t for him.

“Vegan diets are high fiber and high volume,” Moretti said. “You might be feeling fuller at a meal, but the actual calorie amount that you’re taking in would be less than after a meal of chicken and rice. A lot of times people go into a vegan diet and they under-fuel, so just taking in too few calories will lead to relative energy deficiency in sports.”

Moretti said Newton may be better off with a more cyclical diet — going vegan for a few weeks, then eating some animal proteins for a few weeks.

“I’m more of a fan [of the diet] that he was on prior, the pescatarian diet,” she said. “I do think there is a lot of benefits of eating vegetables in the diet, but maybe on your heavier training days you’re incorporating lean protein sources like fish, and I have no issue with chicken and beef in moderation. I think our animal source proteins are still the gold standard for recovery.”

Ben Volin can be reached at ben.volin@globe.com.