Dr Karan Rajan talks about the three supplements he consumes for a healthy life and shares his verdict on popular biohacking methods

Type the words “health tips”, “longevity” or “biohacking” into social media search bars and inevitably you will plunge down a rabbit hole of bad advice, weirdness, and lies. But if you’re lucky you’ll land on the account of NHS doctor Karan Rajan. He’s one of the good guys, with over 10 million followers who watch his videos for no-nonsense, science-backed advice on everything from endometriosis to chia seeds.

We’re all looking to find ways to live a longer, healthier life, – but Dr Rajan says there’s no point spending a fortune on new-age tech or handfuls of supplements if you don’t get the basics right.

“Biohacking and longevity lend themselves to the idea that there is some secret recipe, or a single tablet, or one intervention that you can do which will unlock this new evolution for humans,” he says. “But the unsexy truth is that you have to have the basics dialled in before you start exploring these fringe benefits. Essentially, you can take all these weird supplements, but if you’re not sleeping well, if you’re not getting enough fibre, if you’re not moving and strength training, then these other things won’t paper over the cracks.”

To prove his point, he tells how in 2018 he was diagnosed with high cholesterol and mild fatty liver disease, despite going to the gym regularly and leading what he assumed was a healthy lifestyle.

A look at his diet showed the problem. He was eating almost 200g of protein a day (the recommended amount for men is 55g), with a high-saturated fat intake, and just 10g a day of fibre.

“The high-saturated fat and low fibre was a cocktail that was causing metabolic dysfunction, which manifested as high cholesterol,” he says.

Now Dr Rajan consumes 30-plus grams of fibre a day and has reversed his cholesterol markers.

But he admits that even some of the more fringe supplements popular with online influencers, such as NAD+ (nicotinamide adenine dinucleotide, a coenzyme found in every living cell) and NMN (Nicotinamide mononucleotide, a form of vitamin B3 taken to boost levels of NAD+), which are supposed to boost cellular health, may be worth investigating.

“Whenever I look at fringe products I think about the risk-benefit ratio. What is the benefit that you could achieve from this and what is your risk? Overall, things like NMN or NAD+ are well tolerated. Mechanistic data exists for them. There are some animal studies that suggest they may be robust for longevity. However, in humans the data is lacking.”

Here he offers his expert opinion on the health trends that really will extend your life – and those not worth bothering with.

The three supplements I take

Famous biohacker Brian Johnson reportedly gulps up to 111 supplements a day. Dr Rajan recommends a much more sensible approach.

“Based on meta-analysis, randomised control trials and my own body, I take Vitamin D, algae omega three, and sometimes when my sleep isn’t quite dialled in, I like to take magnesium,” he says.

Fibremaxxing

This viral wellness trend involves people loading meals and snacks with high-fibre foods such as chia seeds, lentils, whole grains, vegetables, and seeds to maximise daily fibre intake.

“That’s probably the safest and most beneficial trend I’ve seen on social media,” says Rajan. And although 30g of fibre a day is a target, it shouldn’t stop there.

“If you increase your fibre intake by just ten grams a day, you already lower your all-cause mortality risk by 10%,” he continues. “The Hadza tribe in Tanzania eat upwards of 100g of fibre a day, and they have some of the lowest chronic disease risk profiles that we see in any cohorts across the world.”

A plant-based diet

“Most studies done over several years, looking at huge cohorts of people, point to a diet high in plant-rich foods as being most associated with longevity,” says Rajan. Mediterranean-style diets seem particularly beneficial.

“You don’t have to eat like a Sicilian uncle,” he continues. “Incorporating things like olive oil and plants high in antioxidants and polyphenols, like berries or darker fruits, and vegetables like beetroot, can maximize chronic disease reduction.”

(He adds that for extra longevity, focus on reducing ultra processed foods, increasing fibre and reducing saturated fat.)

Checking your gut health

Actively taking steps to improve gut health is another easy longevity win.

“Are you eating a wide diverse range of foods? Are you eating enough fibre? Are you eating enough prebiotics?” says Rajan.

He also advises self-monitoring gut health by checking your poo for any significant changes.

“One way to look at how you’re doing is to check your stool every time you go. It’s free data,” he says.

Social interaction

“A lot of longevity data and research suggests that for brain health, for reducing the risk of mental health conditions such as dementia, and for general wellness, connecting with other people and going out in nature are important,” says Rajan.

Sleep

“Make sure that you’ve got some consistency in your sleep. You don’t need to obsess over it, however,” advises Rajan.

Walking – 7,000 steps a day

While 10,000 steps a day is commonly held as the goal to aim for, Dr Rajan suggests that even lower levels of activity will be beneficial.

“We don’t have to aim for that target. There are newer studies suggesting that you get most of the benefits of 10,000 steps at 7,000 steps a day. So, 7,000 seems to be the sweet spot, and any more movement that you’re doing now if you’re not moving much is good.”

Red light therapy

This uses low-level wavelengths of red or near-infrared light to supposedly stimulate cellular activity, promoting healing, reducing inflammation, and improving skin health.

“Good evidence for tissue repair, locally. Ongoing research and trials for systemic effects for longevity are needed however.”

Cryogenic preservation

This involves freezing a person’s body or brain at ultra-low temperatures after death in the speculative hope that future technology may one day revive and cure them.

“This is a weird, wild, and wacky concept. There is no evidence that we can safely reverse a human or any mammal from a cryo-preserved state. Cryopreservation is a complete gimmick at this current stage of science.”

Hyperbaric oxygen therapy

This involves breathing pure oxygen in a pressurized chamber to increase oxygen levels in the blood and tissues, which may promote cellular repair.

“There’s some good data to show it can help in specific use cases, such as severe anaemia, wound recovery, and diabetic foot. But for longevity we need ongoing research and trials.”

I.V. vitamin drips

This involves administering cocktails of vitamins intravenously.

“In someone who is deficient in certain vitamins they can help. However, there is no equivocal data to suggest that they can help someone who is non-deficient in those vitamins or minerals.”

Faecal microbiome/faecal microbiota transplants/poop transplants

This involves transferring stool from a healthy donor into the gut of a recipient to restore a balanced microbiome. It is being explored for its ability to rejuvenate the gut ecosystem, possibly improving metabolic health, reducing age-related inflammation, and enhancing overall resilience.

“This is grounded in science. We know it works for specific cases. If someone has a clostridium difficile infection, which is a nasty bacterial infection of the colon, and if it’s resistant to traditional medical therapies, we can give them a poop transplant, and they can see a reversal and regression of symptoms. It can be very effective at modulating someone’s gut microbiome. Some people have experimented with DIY poop transplants and taken poop transplants from close family members, and anecdotally, it seemed to have worked.”

Parasite cleanses

This practice uses herbs, supplements, or diets to try to eliminate intestinal parasites from the body.

“This is probably the worst social media trend I’ve seen. These are often just a high-dose laxative or a cleanse with various herbal supplements and can be dangerous for gut microbiome health and health in general. In the Western world, unless you are consistently eating undercooked or rotten meat, or you’re drinking well water, or you’re constantly eating food from the soil, it’s very unlikely that you’ll have a parasitic infection. And certainly, being asymptomatic for a long period of time with a parasitic infection is also not very common.”

This weekend, Dr Karan Rajan appears at the Health Optimisation Summit in London, the UK’s biggest event for biohacking, longevity, nutrition and functional and preventative medicine