It was a sensational, X-rated confession that made jaws drop.

Yet Christina Aguilera’s revelation — that she thinks swallowing is good because it has ‘a lot of protein’ — is merely an old wives’ tale.

That is according to doctors, who rebuffed the Dirrty hitmaker’s claim on Call Her Daddy podcast.

Someone would need to consume two gallons of sperm to meet the recommended daily dietary protein requirement, they estimated.  

The whites of one large egg contain around 3.6g of protein, on average.

The whites of one large egg contain 3.6g of protein, while experts say an average load of sperm (5ml) has just 0.25g

Speaking on the Call Her Daddy podcast, Aguilera made clear her stance on the age-old debate of whether to spit or swallow

Meanwhile, studies have suggested an average load of sperm (5ml) has just 0.25g. 

That means, in theory, you would have to ingest 14 ejaculates to match the protein-count. 

During her frank chat, Aguilera, 42, made clear her stance on the age-old debate of whether to spit or swallow. 

She said: ‘I think there’s something to be said after you put in the hard work. I think swallowing is really like a good thing. 

‘And it’s got a lot of protein, I have to say. I’m a promoter of the swallow.’

On whether sperm could be a good protein source, Dr Danae Maragouthakis, a sexual health expert at Oxford-based clinic Yoxly, told Metro: ‘You would need to drink a couple of gallons of sperm to meet the recommended daily dietary protein requirement.’

The recommended amount of protein per kilo of body weight is 0.75g, according to the British Nutrition Foundation — which works out as around 56g a day for men and 45g for women. 

And Dr Maragouthakis said protein levels in sperm can differ between men as the components of semen change with age and health. 

‘The volume of ejaculate, will depend on the last time he masturbated, sometimes it’ll be a little bit more sometimes it’ll be a little bit less,’ she added.

Dr Maragouthakis confirmed that semen could not act a substitute for other protein sources as part of a healthy balanced diet. 

For comparison, a serving of chicken has 25.6g of protein, while a portion of cod has 6.6g.

One food with a low protein content is porridge oats, as an 80g serving has just 1.5g of protein in it – just six times that of an ejaculate. 

Sperm does contain many other nutrients, Dr Maragouthakis added, including citric acid, vitamin B12 and zinc.

And in another video she discussed whether it is safe to swallow sperm.   

She said: ‘Swallowing semen can transmit certain types of infections like chlamydia and gonorrhoea. If you don’t know your partner’s STI status, it’s probably best not to swallow their semen.’

However, if your partner doesn’t have an STI, Dr Maragouthakis insisted there are no known health complications from swallowing.