David Agus strolls down a sunlit Beverly Hills street towards his clinic, palm trees soaring into a cloudless sky, the Hollywood sign glinting in the hills. He bubbles with adjectives such as “amazing” and “wild” and “lucky” for a blessed era – ours. Medical science, he says, can extend and improve human life as never before. The possibilities are limitless.

“We’re at the point where there is a discovery every week that is transformative,” he says. “Our bodies are talking all the time. But now, with technology, for the first time we can listen in. And this is what is going to define these lucky years: listening.”

Agus listens to the human body closely. He is a research scientist, professor of medicine and engineering and a clinician whose patients include billionaires, rock stars and Hollywood royalty. He is also, like his late friend and patient Steve Jobs, an evangeliser for technology-driven progress, a gospel he spreads through mega-selling books and appearances on television and at powwows such as the World Economic Forum in Davos. His focus is not on gadgets but on how scientific breakthroughs can help us “edit our DNA”, adopt healthier lifestyles and customise medical treatment.

“We don’t want people to die young of diseases like Alzheimer’s, heart disease and cancer. We need to delay and prevent them and we now have the technologies to do that. We can live until our ninth or 10th decade and then die of what we call old age, when there is general engineering failure.”

The physician exudes Silicon Valley-style zeal to change the world. Diseases such as pancreatic cancer, which claimed Jobs’s life in 2011 at the age of 56, affront him. “Steve asked me, ‘Why can’t you debug me like I debug a program?’” Agus believes the ability to do that, and much else, is within our grasp. All we need do is collate and heed insights from medical science. It is a heady prospect. Talking with Agus is like floating up into the balmy Los Angeles sky and wondering – hoping – he is right about the azure yonder.

In a crowded field of celebrity doctors and wellness gurus, their advice ranging from common sense to kooky to perilous, the trim 50-year-old is an overachieving hybrid. He combines serious research with patient consultations, TED talks, tech entrepreneurship and spots on CBS with mega-selling books such as The End of Illness and A Short Guide to a Long Life.

His latest, The Lucky Years: How to Thrive in the Brave New World of Health, published this month in the UK, carries endorsements from the likes of Oracle’s Larry Ellison (“an inspiring vision”) and Dell Inc founder Michael Dell (“It sometimes takes a genius to know the difference between what’s good and bad for us amid all the noise in health circles. Thanks, David Agus, for being that genius.”).

The Amazon blurb for The Lucky Years boasts that it gives you “the keys to the new kingdom of wellness”. That’s a stretch. It reviews the latest research into disease and healthcare, taking in genes, drugs, diet, sleep and exercise, and breaks it down into bitesize recommendations. The techno-utopian tone hails a “golden age”, but says patients and physicians need to be savvy and learn how to crunch data, for example, to truly benefit.

The scion of a professor emeritus of medicine and physiology, and a graduate of elite medical schools – Princeton, the University of Pennsylvania, Johns Hopkins – Agus fires out advice in rapid, confident tones. Vitamins, detoxes and juices: bad. Aspirin, statins, earplugs and a Mediterranean diet: good.

Such conclusions, he says, are not his opinion. “It’s the data.” During our interview, Agus cites about a dozen recent, varied studies, all pooling into a knowledge reservoir. In China, for instance, scientists used DNA-editing techniques to alter a gene in human embryos. Changing one letter among the 3bn forming an individual’s DNA code could, for example, stop a breast cancer gene passing on to a child.

Researchers in Princeton and California dusted off a long-neglected, 1950s experiment – a Frankensteinish stitching of young and old rats together – and found that proteins in the blood of young individuals can activate dormant stem cells in older individuals. “The cure for disease is within us,” says Agus. “We now have the ability, through these proteins, once we isolate them, to potentially turn back on these stem cells.”

Citing ethical and safety concerns, a biology summit of international scientists in Washington last month decided it was too soon for clinical use of “germline editing”, but left the door open for later use.

Harnessing healthcare systems’ information troves will mark another huge advance, especially that of the NHS, a repository of centralised, cradle-to-grave knowledge, says Agus. “This is the era of big data and we all have the ability to be part of it.” Protecting patient confidentiality from prying by governments, employers or insurance companies is an issue, he concedes, but he believes the information must be shared. “The solution for many of the diseases we’re talking about is in the databanks of the NHS. It needs to be liberated.”

To illustrate the explosion of data, he takes out his iPhone and opens a free app that measures his heart’s electrical activity through his fingertips. Another app, costing 79p, measures his breathing and pulse by filming his face. “I can build up a record and email it to my doctor,” he says. “It’s a new world.”

Agus was a geek focused solely on science in his youth, but his mentor, Andy Groves, the former CEO of Intel, who has battled prostate cancer, urged him to sharpen his communication skills. Moving to LA in 2000 reinforced the message. A Hollywood friend gave him a “great gift” – a focus group analysis. It taught him to allay suspicion of being a drug industry shill (he doesn’t receive a cent, he says), and to tone down references to high-powered patients, lest ordinary people assume such treatment is beyond humbler means.

Jobs, a marketing savant, changed the original title of Agus’s first book, What Is Health? “He said health is a bad word. It’s like chewing cardboard, people’s eyes glaze over. You need to put something positive, declarative.” The End of Illness duly topped the New York Times bestseller list. The Apple co-founder’s influence is also apparent in Agus’s outfit: black slacks and white dress shirt beneath a black sweater.

Agus treated Jobs after he had abandoned his attempt to fight cancer with a fruitarian diet and embraced, too late, conventional medicine. “He kicked himself that he took things to an extreme. It’s empowering when you go on a diet. You think you’re doing something.” Agus pauses. “I unfortunately have to look people in the eyes several times a week and say I have no more drugs to treat your cancer. I don’t want to do that any more.”

Agus thinks scientific advances have opened the door to a new era. But we’re not stepping through it because medical consensus plods slowly, cautiously, and the internet squawks with cranks and charlatans. So ordinary people hesitate, in want of a reliable guide.

“With enough data, error goes away. But the data needs context. The internet is remarkable but there’s a lot of noise. Everybody’s saying everything. So in order to get normative behaviour change based on data, you need leadership. The reason I write books is to try to provide some of that leadership.”

It’s a bold ambition reflected in his clinic’s wall hangings: quotes from Winston Churchill (“we shall fight on the beaches… we shall never surrender”) and Albert Einstein (“knowledge must continually be renewed by ceaseless effort…”), plus an image of the physician Edward Jenner giving a young boy, reputedly his son, a pioneering smallpox vaccination. “That changed the world,” says Agus.

Not everyone is a fan. Gathering enough data until “error goes away” can sound like hubris. Some critics accuse Agus of getting ahead of the evidence in a media-friendly quest for clarity and directness. When in 2012 he bluntly warned an ABC News reporter, a test subject, that he was at risk of a heart attack, five doctors said he overstated the risk.

Seated in his office, Agus bats away the criticism, saying solid research grounds his conclusions. “I get to cheat. I know many of the studies years before they’re published.” If the data is not definitive, his conclusions reflect that, he says. But some things strike him as clear cut.

“There’s a notion that vitamins mean life, and more is better, but the data don’t support it. In over 60 randomised studies of multivitamin versus placebo, none, zero, ever showed a benefit. Lots of side-effects but no benefits. We spend more on vitamin supplements in the United States than we do on all of medical research. There’s something wrong there.” Slick marketing and a yearning for quick fixes feed the industry, he laments. “It’s a crutch. When I say that, people get pissed off.”

Agus strives to follow his own injunctions. Every day he takes a baby aspirin to lower the risk of cancer and heart disease and a statin to lower cholesterol and block inflammation. Agus shrugs off critiques from colleagues who say healthy people should not take statins. “Look at the data,” he says. He scorns detoxing and juiced fruits and vegetables. “Whenever you put them into a blender, or squeeze them out, they degrade right away because of the oxygen and light. So there is no nutritional value, there’s just sugar.”

Agus says fad diets don’t work. “There’s been a fad diet coming out every year or two for the past 50 years. If one was superior to another, we’d be doing it.” He advocates a Mediterranean diet with regular mealtimes – and moderation. For instance, no more than two glasses of red wine a night to avoid waking up a few hours later with a rebound surge of adrenaline. Three cups of coffee daily can have a health benefit, he says. “So I have two cups. But not after 11am because then I don’t sleep so well.”

He values deep sleep. When watching TV in the evening he wears glasses to filter wavelengths that the brain confuses with sunlight. “It thinks, hey, I’ve got to be awake.” To sleep through his dog’s snoring Agus wears earplugs, a habit based partly on an English study that showed increasing neuron-cognitive decline the closer people lived to airports. “If you live near an airport, or in the middle of a city, it’s not that you’re doomed, it’s that you need to take steps to protect yourself.”

Early to bed, he rises around 4am or 5am and exercises for an hour, alternating yoga, Pilates and tennis. “I don’t love yoga, but it works. My body needs it. When I skip it I feel it.” A tracking device “shocked” him over the daily hours spent sitting. “So I got a treadmill desk and try to do one walking meeting a day.”

Instilling healthy habits in children, he concedes, is challenging. He lectured his kids in vain about chocolate milk affecting levels of insulin and cortisol, a steroid hormone. Then they watched Jamie Oliver fill a bus with sand to show how much sugar in the form of flavoured milk LA children consume weekly. “The next day they stopped drinking chocolate milk,” marvels Agus. “He knew how to speak their language.”

Before the interview, I supplied blood and urine samples so Hollywood’s favourite physician could analyse my results. He scans the pages. Blood counts, sugar levels, electrolytes, all normal. Cholesterol fine. He stops.

“Ah! You do have an abnormality. A cool one.”

A cool one?

“Yes. Do you know you have Gilbert’s syndrome?”

Er, no.

“It’s awesome. It means when you’re stressed you don’t conjugate bilirubin and degrade it well. Classically, people like that, when they have a stressful situation, the whites of their eyes turn yellow.”

This is awesome?

Agus nods and smiles. “There’s no harm to the body.”

I’m not sure about awesome, but sort of fathom his enthusiasm. It is, after all, data.

The Lucky Years: How to Thrive in the Brave New World of Health by David Agus is published by Simon & Schuster on 5 January (£12.99). Click here to order a copy for £10.39

Body talk: David Agus’s way to wellness

In his latest book, David Agus instructs readers to take his “two-week challenge” to plan for optimal health. The key points of this regime are…

■ Measure your blood pressure twice daily using a smartphone device. Make a note of how you are feeling when you take these readings.

■ To understand the genetic risks to your health, investigate your family’s medical history for causes of death. Look for contributory lifestyle factors such as smoking, poor diet, or any mental health problems.

■ In as much detail as possible, make a journal of your eating habits. Record how you feel in the hours immediately after eating.

■ Make a note of any exercise you do.

■ List all the medication and supplements you take and the reasons for doing so.

■ Record any unexplained symptoms you experience.

■ Make a note of how you feel each day – depressed, cheerful, stressed etc.

■ Document your sleep schedule: the quality, the quantity, whether you dream or not, what you do before sleeping.

■ Log the time of your peak and lowest energy levels each day.

■ Overlay all this information and look for patterns. Do certain foods lead to changes in your mood, energy or sleep? Does the time of day that you exercise affect the quality of your sleep? Test these observations by changing your behaviour and noting what the result is.

■ Ask your doctor to test your cholesterol, CRP (C-reactive protein, a measure of inflammation in the body), CMP (comprehensive metabolic panel, a measure of liver and kidney function, as well as conditions such as diabetes) and hemoglobin A1C (your average blood sugar level).

■ Discuss the results with your doctor.