A multi-millionaire biohacker on a mission to become 18 again has revealed how he reversed his male pattern baldness and returned the colour to his luscious locks in less than a year.

Bryan Johnson, 47, has become known for pursuing an extensive range of therapies and treatments in a bid to reduce his biological age - and he has seemingly turned the clock back on his hair loss too.

Mr Johnson said while he should be "genetically bald" by now, after embracing nutritional, topical and even light treatments, he now has a full head of hair with 70 percent fewer greys.

Taking to Twitter/X to share his impressive results, he said that it is possible for men to keep their hair "well into your 40s and beyond" if they take the right steps.

However, Mr Johnson advised that those wishing to prevent hair loss should begin to act before it even happens. "Many lose up to 50 per cent of their hair before they even realise it," he wrote.

He explained that in his case, taking the right vitamins has been key to getting his hair back, citing the benefits of protein and Omega-3 fatty acids.

Another treatment that helped the issue was topicals, which Mr Johnson, who sold his company Braintree Venmo to PayPal for $800m in 2013, has personalised to his genetics.

His formula contains several ingredients including melatonin, caffeine and Vitamin D3.

Mr Johnson, from Utah, also embraced red light therapy, even wearing a hat to administer it as he went about his day.

The final treatment praised by the biohacker in reversing his hair loss was oral minoxidil - a topical hair loss drug.

However, he stressed that it is only considered safe at low doses as it can lead to unpleasant side effects, including excessive hair growth and headaches.

News of the biohacker's hair loss reversal comes after he recently revealed that he had a "total plasma" exchange in a bid to remove toxins from his body.

Plasma is the part of the blood that carries cells around the body and plays a key role in removing waste from the body.

Mr Johnson's plasma was removed and replaced with albumin, a natural protein-based substance that helps in the growth and repair of tissue, a procedure experts have likened to a human oil change.

"The operator, who's been doing TPE for nine years, said my plasma is the cleanest he's ever seen. By far. He couldn't get over it," the multi-millionaire said.

However, while Mr Johnson now dedicates a significant portion of his time to pursuing health and wellness, he told The Independent that this was not always the case.

"I would routinely commit self-destructive behaviours, and specifically in the evening at seven o'clock, I would try to soothe my stress by eating food," Johnson recalled. "And that caused me to gain a lot of weight, and that caused me to not sleep very well, which then caused me to not feel very well in life."

"I basically removed myself from taking care of myself and built a system in place that takes better care of me than I could of myself," he said.