Hi everyone,
Longevity is having a moment. There was a conference in London last weekend — celebrities, clinicians, biohackers, the lot — and I'll be honest, I found myself reading the recap with one hand hovering over my credit card. The peptides, the panels, the wearables. It's genuinely fascinating territory, and I'm not dismissing any of it.
But I keep coming back to the same thought: most of us haven't yet mastered the basics. Sleep, sunlight, meals that actually nourish us, time with people we love and a nervous system that isn't running on alert. If those foundations are solid, then yes, explore further — go for it. If they're not, as the guests on The Health Review podcast often tell me, no gadget is going to paper over the cracks.
Emily x
☀️ A study challenges the idea that summer sun gives you all the vitamin D you need
A study by the University of Surrey of nearly 300 people across northern Britain found that vitamin D levels often stay low all year in groups most at risk — and surprisingly, summer sunshine did not significantly boost vitamin D levels in these groups.
🧬 Scientists pinpoint why our waistlines change with age, even when our weight doesn't
manufacturing entirely new ones
🧠 Fish oil supplements might not protect the ageing brain
two-year placebo-controlled trial
🦴 Osteopenia is silently weakening bones in millions of people
Research suggests Osteopenia affects around 40% of adults, and postmenopausal women are particularly vulnerable — one in two women over 50 will suffer a fragility fracture. The condition rarely announces itself before a bone breaks. Oestrogen helps slow natural bone breakdown, so its decline after menopause accelerates the process considerably. The practical levers are more straightforward than you might expect: weight-bearing movement (walking, dancing, jogging), resistance training, and enough calcium and vitamin D in your diet.
🪑 Your cells feel the effects of sitting
If you're healthy but not especially active, your mitochondria — the tiny structures inside cells that convert food into energy — may already be working less efficiently than they should. Researchers at the University of Colorado Anschutz found that sedentary men had a fat-burning enzyme that was roughly half as active as in regularly active men, and a sugar-processing protein that was nearly 50% lower. The lead researcher describes this as an early warning sign that could, over 10 to 15 years, contribute to conditions like insulin resistance, diabetes, or worse. The study was small — 19 men — and a women's study hasn't happened yet. But it's a compelling nudge to keep moving.
Today's issue is supported by SONA
Today's newsletter is supported by SONA, an AI-powered vagus nerve stimulator that sits comfortably inside your ear. Earlier this year I had SONA's founder, Jane Ollis, on the podcast for a proper deep dive into the nervous system — one of my favourite conversations on the show, and well worth a listen if you haven't already. The device itself targets the auricular branch of the vagus nerve via the ear and adapts its stimulation in real time to your body, rather than using a fixed setting — built by a genuinely brilliant team of neuroscientists, astrophysicists, researchers and engineers. The Health Review readers get 15% off with code THR at checkout.
The 29-year-old with the body of a 78-year-old: what biological age testing actually reveals
A 29-year-old walks into a longevity clinic and leaves with a biological age of 78. It's a real case from Dr Alka Patel, a GP and longevity doctor I sat down with this week. The biggest factor she identified was stress. So before you order one of the at-home kits currently advertised on social media, it's worth understanding what the number is, and what it isn't.
Why clinics use biological age tests — and what they're actually measuring
Your chronological age is just how long you've been alive. Your biological age is an attempt to measure how much your cells and tissues have aged in that time — and the two can diverge significantly. Longevity clinics use biological age testing because it gives patients a concrete, personal number that a conversation about "lifestyle risk factors" rarely does. For many people, seeing a figure that's 10, 20, or in Dr Patel’s patient’s case nearly 50 years above their actual age is the first thing that cuts through.
Most tests do this by reading chemical tags on your DNA — a method called epigenetic clocking. These tags shift predictably as we age, and the pattern they form can be used to estimate biological age. The original version of this approach, published in 2013, was a genuine scientific leap. The at-home kits sold today are descendants of that work, with varying degrees of rigour. Different providers use different algorithms and different sample types — saliva, blood, cheek swabs — and can produce different numbers for the same person on the same day. A 2022 reproducibility analysis found some commercial clocks varied by several years on repeat samples from the same individual. So when Patel's patient registered as 78, the figure is striking, but it's a signal, not a verdict.
Cortisol is the more useful number
The test that changes how Dr Patel treats people isn't the biological age score. It's the cortisol curve.
Cortisol typically rises within roughly 30 minutes of waking — the cortisol awakening response — then declines across the day. A single blood draw at the GP tells you almost nothing about whether that rhythm is intact. A diurnal profile, usually four or five saliva samples across one day, shows whether your curve is flattened, inverted, or stuck on high in the evening. Each pattern carries different downstream effects on sleep, immunity, and metabolism. Diurnal cortisol profiling isn't available on the NHS; private testing runs from £100 to £250 depending on the provider, and interpretation isn't always included in that price.
How stress ages you faster
Patel says cortisol testing is particularly popular with executives and high performers. The concept of allostatic load — the cumulative wear-and-tear of chronic stress on the body — was first described by Bruce McEwen and helps explain how someone can feel entirely functional while their physiology is quietly out of rhythm.
One of the clearest mechanisms behind this is what chronic stress does to telomeres — the protective caps at the ends of your chromosomes. Each time a cell divides, telomeres shorten slightly; when they become too short, the cell can no longer replicate. Sustained high cortisol accelerates that process. Studies of caregivers, people in high-pressure jobs, and those who experienced early-life adversity consistently show shorter telomeres than age-matched peers. In other words, stress doesn't just feel ageing — it drives the biology of it.
Uncertainty isn't a reason to wait
When it comes to genetics versus lifestyle, nobody knows the exact split. What twin and cohort studies do suggest is that lifestyle accounts for a meaningful share of how we age. The levers are real even if the maths is fuzzy, which makes the case for acting now.
The cortisol curve responds, slowly, to lifestyle architecture: sleep consistency, morning daylight, when you train, when you stop caffeine, how you wind down. A flat curve and a spiked curve need different support, though, which is why testing without interpretation tends to waste money.
How to use this, this week
Audit your last 24 hours before booking any test: what time did you wake, get daylight, finish caffeine, finish eating, and fall asleep? Inconsistency here is the most common driver of a dysregulated curve, and it costs nothing to check first.
If you're going to test, ask specifically for a four-point diurnal salivary cortisol profile with clinical interpretation included. A one-off blood cortisol from your GP won't answer the question.
Treat any biological age result as a conversation-starter, not a diagnosis. Ask which clock the provider uses, whether results are reproducible on repeat testing, and what the confidence interval is on your number.
This feature is for educational purposes only and does not constitute medical advice. Always consult your own doctor before making changes to your health.
How to Live to 114 in Great Health | Longevity Doctor Alka Patel
