Staying vital with age: energy, sleep and the blood values to check

Around 50, I keep hearing the same line: "I'm older now, so this is just how it is." Sometimes that's true, but often it isn't, and that gap is what staying vital with age is really about. Part of your energy dip is simply age. Another part is measurable, and you can check it before you accept it.

What strikes me in practice: fatigue after 50 gets waved away as age too easily, while a shortage of ferritin, vitamin B12 or vitamin D sometimes sits underneath.

A thyroid that runs slower can play a part as well.

What does staying vital with age mean?

Staying vital with age means you keep enough energy for the things you want to do while your body slowly changes. It's not about feeling twenty again. It's about function: the stairs without getting out of breath, thinking clearly, and waking up rested in the morning.

Vitality isn't an age. It's a sense of reserve.

Picture two people of 58 on the same walking holiday. One is puffing on a rock after an hour of climbing, the other strolls on. Same age, different stamina.

That gap comes partly from exercise and genes, and partly from things you can measure. It's that measurable part this article is about.

Why do you have less energy as you get older?

Less energy with age comes from a stack of small things. Your mitochondria, the little power plants in your cells, work a little less efficiently. Your sleep gets lighter and shorter. On top of that, shortages of iron, vitamin B12 or vitamin D can play a part, plus a thyroid that runs slower.

The first two are biology. There's little to steer there.

Over the years the number and quality of mitochondria in your muscles gradually fall, and you notice it most during effort that needs stamina.

Your sleep architecture changes too. You spend less time in deep sleep, the stage where your body recovers most, and you wake more often at night.

But watch that third part, because that's where it gets interesting. Fatigue from a shortage looks exactly the same from the outside as fatigue from age. The difference is that you can measure one and not the other.

That's often where it goes wrong. Someone of 55 blames flat energy on age, while a low ferritin has been simmering underneath for months.

Which blood values say something about your energy?

Four blood values come up most around energy: ferritin, vitamin B12, vitamin D and TSH. Ferritin says something about your iron stores, B12 and vitamin D about common shortages, and TSH about how hard your thyroid works. None of these is a diagnosis, but together they give direction.

Ferritin is the storage form of iron, and a low store can go together with fatigue, even when your anaemia value still reads normal. In a trial of 198 menstruating women with a ferritin below 50, fatigue fell more after twelve weeks of iron than with placebo (PMID 22777991).

With ageing, vitamin B12 plays a part of its own. A shortage is relatively common in older people, partly because uptake from food drops over the years (PMID 15289425).

If you want to know what a low ferritin actually means, you can read it back on the marker page about ferritin.

Then the thyroid. In a long-running study, TSH rose on average with age while free T4 didn't change, which suggests a slightly higher TSH later in life doesn't automatically mean disease (PMID 22344200).

Important: this table points to directions, not diagnoses. An off value asks for your GP's explanation, not your own conclusion.

If you want a broader look at vitamin shortages and which ones you can have drawn, read recognising vitamin deficiency symptoms.

What does sleep do to your ageing body?

Sleep is the stage where your body recovers, and that stage changes over the years. You sleep lighter, wake more often and spend less time in deep sleep. Research links poor sleep to more daytime fatigue, though the relationship is complicated and certainly not one-way.

The link between sleep and energy stays underexplained in most lifestyle advice.

What I often see people do: they chase more hours, while quality is the real problem. Six hours of unbroken sleep often feels better than eight with four wake-ups.

Sleep and the values from the previous section are connected too. A thyroid running too fast or too slow can disturb your night's rest, and poor sleep can in turn drag down your energy by day.

This is an area where I stay careful. You don't measure sleep with a tube of blood, and one bad week says little.

How do you stay vital?

Staying vital is linked in large part to moving, enough protein and routine in your sleep. Strength and endurance training keep your muscles and your mitochondria at work. Protein can help you hold on to muscle mass, and that muscle tissue is what keeps your stamina up as you get older.

This is the part you hold most in your own hands.

Movement is the lever you have the most influence over. Two strength sessions a week can help your muscles and your energy, and it's never too late to begin.

The Voedingscentrum, the Dutch nutrition authority, advises extra vitamin D in the winter half-year for people over 70 and for some groups below that, precisely because skin production is low then. Treat that as context, not a personal prescription.

Muscles and bones travel together here. If you want to know which values relate to your bones, read preventing osteoporosis: vitamin D and calcium.

And for the wider picture of ageing, with the values that most often go with it, there's 7 signs of ageing.

Where do you start?

Don't start with everything at once, but with one question: has my energy really changed over the last few months? For a week, write down how you feel in the morning, how you sleep and when you sag. Take that to your GP, or have a few basic values drawn as a starting point.

That little list is worth more than a vague "I'm tired".

If you're persistently tired for no clear reason, persistent fatigue: causes of tiredness covers which values can give insight.

If you want several of these values measured at once, you can look at the extended health checkup, which includes ferritin, vitamin B12, vitamin D and TSH among others.

And for the big line from your 40s on, there's the overview in healthy ageing: which blood values to monitor.

My advice stays plain. Don't accept less energy as age straight away, but check the measurable part first. A value is a starting point for the talk with your GP, not an end point.

References

1. Vaucher P, Druais PL, Waldvogel S, Favrat B. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012;184(11):1247-1254. PMID 22777991.
2. Andres E, Loukili NH, Noel E, et al. Vitamin B12 (cobalamin) deficiency in elderly patients. CMAJ. 2004;171(3):251-259. PMID 15289425.
3. Bremner AP, Feddema P, Leedman PJ, et al. Age-related changes in thyroid function: a longitudinal study of a community-based cohort. J Clin Endocrinol Metab. 2012;97(5):1554-1562. PMID 22344200.
4. Voedingscentrum and Thuisarts. Public information on vitamin D, vitamin B12 and fatigue. Available via voedingscentrum.nl and thuisarts.nl.

Every blood test result at Vitalcheck includes a professional assessment by a BIG-registered doctor. A blood value is not a diagnosis: always discuss treatment decisions with your GP.