Calcium, vitamin D and strong bones: what every woman over 45 should know

Arriving at 60, 70, and 80 in good shape isn't a matter of luck. It depends largely on how you treat your bones today. It's easy to go at that question with half the information, especially if you're a woman past 45. You've been told to take calcium and you've been told to take vitamin D, but the third leg of the stool gets far less airtime, and it happens to be the most important of the three: mechanical loading. Without it, calcium and vitamin D deliver far less than they promise.

This article is for you if you're in the 45-65 range, if your mother had osteoporosis, if you're a woman going through menopause, or if you're a man in your 60s who has started to notice that your bones aren't what they were. You'll come away knowing how much calcium you actually need, how to get it from food, and how much vitamin D you need month by month at your latitude. You'll also know which exercises really build bone and when it makes sense to supplement.

What osteoporosis is and why it almost never hurts

Osteoporosis is a silent disease. It doesn't hurt, it doesn't warn you, and from the outside there's nothing to see. It shows up once your bones have lost enough mineral density to turn fragile. You may not notice a thing until the first fracture arrives: a wrist caught while breaking a fall, a hip after a trip, a vertebra that collapses with no obvious trauma.

Bone isn't dead material, it's living tissue that keeps renewing itself. Two kinds of cells work inside it: osteoclasts, which break down old bone, and osteoblasts, which build new bone. When you're young the osteoblasts win, and past 35 the osteoclasts start winning instead, quietly enough that nothing feels different. Menopause turns that slow drift into a spike, because there's no longer enough estrogen around to hold osteoclast activity back. In the years after your last period you can lose a sizeable share of your bone density if you do nothing about it.

The catch is that bones don't hurt while they're losing density, they hurt once they're already broken. By the time you notice the first symptom, prevention is behind you. That's why the only strategy that works is acting long before any symptom shows up.

The three levers: calcium, vitamin D, mechanical loading

Three main factors determine your bone density, and you need all three of them. One or two won't do the job.

Calcium is the raw material: without enough of it in your blood, your body has no blocks to build bone with. And if you don't supply it through food, it takes what it needs out of your own bones, which is a bad trade.

Vitamin D is the transport. You can eat all the calcium in the world and it won't matter much, because with low vitamin D your gut absorbs only a fraction of that calcium, while with vitamin D in range you absorb a good deal more.

Mechanical loading is the construction engineer, the one that tells your osteoblasts to build right here. Without it, all the calcium and all the vitamin D in your system leave the bone with no idea where to put any of it. Mechanical loading means strength training with real weights.

Think of it as building a house: calcium is the bricks, vitamin D is the truck that hauls them to the site, and strength is the architect who decides where to build, and without all three the site doesn't move forward.

How much calcium you need (and why it is not just milk)

Official recommendations for healthy adults run between 1,000 and 1,200 mg of calcium a day, and for postmenopausal women and men over 70 the figure is 1,200 mg. You don't have to obsess over the exact number, but you do need to know whether you're anywhere near it or nowhere close.

Milk and dairy are the famous source, and they earn the reputation. A glass of milk (250 ml) gives you around 300 mg, a plain yogurt gives you 200 mg, and a 30 g piece of aged cheese gives you 250 mg. Three servings of dairy a day already put you at 800-900 mg. The rest you fill in with calcium from other foods.

But if you don't do dairy, whether from intolerance, preference, or veganism, you can hit the target without any trouble, and these are the most efficient non-dairy sources:

Canned sardines with bones (100 g) carry 380 mg, which makes them the most underrated source on the list.

Almonds (30 g): 80 mg.

Cooked broccoli (200 g): 140 mg.

Cooked chickpeas (200 g): 100 mg.

Kale (100 g): 150 mg.

Tofu set with calcium sulfate (100 g): 350 mg, though you'll want to read the label, because not every tofu is rich in calcium.

Fortified plant milks (250 ml): 300 mg. Almost all the good ones are fortified, and homemade versions without fortification don't carry enough calcium to count.

Sesame seeds (30 g): 280 mg.

Dried figs (100 g): 160 mg.

Three canned sardines, a handful of almonds, a portion of chickpeas, and half a head of broccoli add up to 800 mg of calcium. Not a drop of dairy in sight.

The myth of the daily glass of milk

There's a lot of noise about whether milk is the best source of calcium or not. The truth is duller than either camp would like: milk isn't mandatory, but it is conveniently rich in calcium and easy to work into a day. If it agrees with you, keep it, and if it doesn't, there are equivalent alternatives, because the fanaticism for or against dairy usually traces back to commercial interests rather than to the science.

Vitamin D: yes, you are probably low

One of the most widespread myths holds that vitamin D deficiency can't happen where there is plenty of sun. It can, and it does. Living in a sunny Mediterranean region is no guarantee that your levels sit in the optimal range. The reason isn't mysterious: we spend the day indoors, we work inside, we put on sunscreen when we go out, and in winter the sun is weak even at the sunniest latitudes.

Your body makes vitamin D in the skin, and only when direct sun reaches it. No cream, no clothing in the way. The factory is your skin, not your plate, though a few foods do contribute a little.

Here is how much sun you need month by month at around 36 to 40 degrees north. The figures assume a light-to-medium-skinned person outdoors with arms and legs exposed:

May to August: 10-15 minutes between 11 a.m. and 4 p.m., two or three times a week, and that is enough. Past that window, UV radiation does more damage than good and you should be protecting yourself.

September and April: 15-20 minutes a day in the central hours, two or three times a week.

October to March: the sun is weaker, and even an hour outside at midday leaves your skin producing very little vitamin D. For most people over 50, supplementation across these months is close to mandatory.

If your skin is dark, double those times, because melanin shields you from radiation: good news for skin cancer risk, bad news for vitamin D synthesis. That's why people with dark skin living at high latitudes so often carry a chronic deficiency.

To find out where you stand, ask for blood work that includes 25-hydroxyvitamin D, ideally landing between 30 and 50 ng/ml. Below 20 counts as clinical deficiency, and 20 to 30 counts as insufficiency. Plenty of routine panels leave the test out, so you have to request it by name.

Mechanical loading: the exercise that actually builds bone

This is the leg of osteoporosis prevention that gets forgotten most often. Calcium and vitamin D are essential, no argument there, but without specific mechanical loading your bone has no reason to believe it's being used for anything. Bone that isn't used gets recycled.

That said, the claim shouldn't be inflated. Researchers reviewing 8 trials with 379 participants, women both before and after menopause, found small but significant improvements at the femoral neck and the lumbar spine, and only in the postmenopausal ones, while the authors themselves warn about methodological limits in the studies they pooled. Loading is still the lever that moves bone the most, but the effect is modest rather than spectacular.

Not all exercise builds bone equally: walking helps a little, running helps more. The strongest stimulus of all is loading with high impact or high mechanical tension, and that means things like these:

Squats with weight. Holding load over your spine and legs tells the femur, the tibia, and the vertebrae "there is work here, reinforce", and it is the exercise with the most evidence behind it for building hip and spine bone.

Deadlifts cover much the same territory, loading spine, hip, and legs, with dumbbells or a barbell depending on your level.

Loaded pushes and pulls: chest press, shoulder press, row, lat pulldown. They load shoulders, wrists, and the upper spine, all of them frequent sites of osteoporotic fracture.

Controlled jumps deserve a line of their own. Three sets of 10 jumps a day, landing softly, are one of the most efficient stimuli there is for the hip. The caveat matters: do them only if your body tolerates them and you don't already have established osteoporosis.

Unilateral work, meaning lunges, step-ups, and the Bulgarian split squat, loads one leg at a time, which stresses the bone asymmetrically and forces it to adapt.

What doesn't build bone in any meaningful way: cycling, swimming, gentle Pilates, mat yoga. None of them are bad exercises and they carry other benefits, cardiovascular fitness, mobility, flexibility, but for bone they're worth little, which is why professional cyclists paradoxically tend to have lower bone density than the general population: hours of pedaling, and no impact reaching the bone.

How many times per week

Two well-planned strength sessions a week are enough to hold and gain bone, as long as you stay consistent over months. Three sessions speed things up slightly, while four or more doesn't multiply the result, it only piles on fatigue and risk.

What makes the difference is progression. Train two days a week with the same 3 kg dumbbell forever and the bone gets used to it, then stops responding. Add a little weight every two weeks or every month and the bone keeps getting the "build more" signal, which is why progression isn't optional.

What your DEXA (bone density scan) says

If you're over 50, if your mother had osteoporosis, or if you've broken something from minor trauma, it's a good idea to get a DEXA scan, a quick and painless test with very little radiation that measures the mineral density of your bones.

The result comes back as two numbers. One is the T-score, the other is the Z-score.

T-score compares your density with that of a healthy young adult. Between 0 and -1 you're fine, and between -1 and -2.5 you're in osteopenia, which means low density that isn't pathological yet. Below -2.5 is clinical osteoporosis, and that's the point to act with a medical plan.

Z-score compares your density with people of your own age and sex, and a Z-score that sits very low for your age group points to specific factors that need investigating.

If there's reason for concern, the DEXA gets repeated every 1-2 years, and it's the most serious way to find out whether your plan of calcium, vitamin D, and strength is working at all. A measurable change in density usually shows up at 12-18 months of serious training.

Supplements: when yes, when no

The golden rule runs in order. Food first, sun second, supplement third.

And here you deserve honesty about what has actually been measured. Researchers pooling 33 randomized trials with 51,145 adults over 50 who lived in their own homes found no association between taking calcium, vitamin D, or both and suffering fewer fractures: not hip, not non-vertebral, not vertebral, not total. Dose made no difference, and neither did sex, nor having already broken something, nor the calcium the diet carried, nor the vitamin D level at the start. The authors conclude that the findings don't support routine use of these supplements in older people living in the community.

Translated: covering your calcium and your vitamin D still makes sense, so that you never drop below what your body needs. What you can't expect is for pills stacked on top of a diet that already gets there to save you from a fracture, because that hasn't been shown. What does move bone density is mechanical loading.

Calcium supplement. This one is for you only if food doesn't get you to 1,000 mg per day. The typical dose is 500 mg of calcium citrate a day, split into two intakes, and while carbonate is cheaper it absorbs worse, so citrate wins. One caution: the review that raised the alarm pooled 15 trials in participants averaging over 40 years of age, using calcium supplements of 500 mg per day or more, and that's exactly where the higher cardiovascular risk turned up. The ideal is calcium through food, with a supplement covering nothing but the gap.

Vitamin D supplement. Common, and at our latitude very advisable, with a typical maintenance dose of 1,000-2,000 IU of vitamin D3 per day. If you have documented deficiency, meaning below 20 ng/ml, your doctor may prescribe higher doses for a few months to bring the level back up. Don't experiment with very high doses on your own: vitamin D is fat-soluble, and chronic excess accumulates.

Vitamin K2. It helps calcium land in bone rather than in your arteries, which is why it's considered good company for vitamin D. The typical dose is 100-200 micrograms per day of K2 MK-7. It replaces nothing, but it does help.

Magnesium. An important cofactor in calcium and vitamin D metabolism, and it's easy to run low without noticing. Aim for 300-400 mg per day of magnesium glycinate or citrate. Magnesium oxide is cheap and poorly absorbed.

Protein. With age it's easy to fall short on it, and bone pays for that too, because bone is a collagen matrix, collagen being protein, onto which calcium gets deposited. Without enough protein, bone doesn't build well. The base to aim for is 1.4-1.7 g of protein per kilo of body weight.

Osteoporosis medication

If you already carry an osteoporosis diagnosis, meaning a T-score below -2.5 or a fragility fracture, your doctor will probably propose medication in addition to diet and exercise. The most common drugs are bisphosphonates such as alendronate and risedronate, which slow bone destruction, and in more severe cases there are anabolic drugs like teriparatide that build bone directly.

These drugs are useful rather than perfect, and they carry side effects worth keeping in mind. If they're prescribed, it's because the risk-benefit balance justifies it. The point to hold onto is that medication doesn't replace exercise: medication and strength together work better than either one alone.

How to fit all this into a real-life routine

The typical problem after reading an article like this one is that the information is clear while the application isn't, so here is a sample week that folds calcium, vitamin D, and strength together without adding extra hours to your day.

Monday. Breakfast is plain Greek yogurt with almonds and honey, 300 mg of calcium. At midday, a 20-minute walk in the sun before lunch covers vitamin D synthesis, and lunch itself is a salad with canned sardines with bones, another 380 mg of calcium. The afternoon holds a 50-minute strength session, and dinner is eggs with steamed broccoli and fresh cheese, 200 mg more. Total for the day: approximately 1,000 mg of calcium.

Tuesday. No strength work today. A 45-minute walk in the sun instead. Any day with dairy in it, a glass of kefir at breakfast, aged cheese at lunch, yogurt for dessert, adds 900-1,000 mg.

Wednesday. Breakfast is a fortified oat milk, 300 mg, and lunch is sautéed tofu or legumes. The strength session goes in the afternoon, and dinner is baked salmon. Add it all up and the day's calcium hovers around 1,000 mg.

That's a full week, and it isn't a diet. It's a way of eating and moving that, kept up for years, hands you bone density and muscle and sharply lowers your fracture risk by the time you reach 70.

Myths worth burying

"Calcium gives me kidney stones." It's the reverse: very low-calcium diets raise the risk of oxalate stones, while adequate calcium from food protects you. Very high supplemental doses can raise the risk in people who are predisposed, which is one more reason food-based calcium is preferred.

"Dairy makes me gain weight." Whole or skim, dairy shows no robust correlation with weight gain in adults. A 150 g Greek yogurt carries 150 kcal, so it is neither the cause of your weight nor the solution to it.

"The sun causes cancer, so I always avoid it." Prolonged sun radiation and repeated burns do raise skin cancer risk, but 10-20 minutes of brief exposure without sunscreen, several times per week, do not. What raises a risk of its own is the chronic vitamin D deficiency that comes from dodging the sun all year: this is a matter of dose, not of complete avoidance.

"Exercise will break my already weak bones." Well-progressed exercise does exactly the opposite: it's the stimulus that makes bone rebuild itself. What breaks fragile bones are falls with no muscle to brake them, which is why more strength = fewer falls = fewer fractures.

Warning signs to see the doctor

If you're over 50 and any of these things happen, make an appointment: a fracture from very minor trauma, say you fall at home and break your wrist, height loss of 2 cm or more compared with your young-adult height, or back pain that appears without a clear reason and doesn't go away in weeks. A recent diagnosis of chronic inflammatory disease or a stretch of prolonged corticosteroid use belongs on the same list, since both are major risk factors.

None of this is cause for panic, but it is cause to act early. Osteoporosis treated in time gets stopped and, with exercise, even partially reversed, while osteoporosis treated late is much harder to handle.

Questions I hear every week

"Can I take calcium and vitamin D at the same time?" Yes, and in fact many supplements combine the two in a single pill. If you take them separately, put the calcium with a main meal, since stomach acid helps absorption. Vitamin D goes with a meal that contains some fat, because it is fat-soluble.

"Are jumps dangerous with already-diagnosed osteoporosis?" With established osteoporosis, jumping without supervision isn't recommended, so go for movements with firm weight on the ground instead: squat, deadlift with dumbbells, press, row. The bone responds just as well and the risk is far lower.

"How long does it take to notice a density change?" Between 12 and 18 months of serious training and correct nutrition. Before that, the scan won't show it. Other things will, though: less lower-back pain, fewer joint cracks, better balance, more grip strength.

"Do I have to take vitamin D every day or can I do weekly megadoses?" Both systems work if the total comes out similar, and what matters is consistency. For most people, a daily dose of 1,000-2,000 IU is comfortable and effective.

If you only do three things

One: train strength twice a week with progressive loads, and pink 500 g bands don't count. Dumbbells, machines, barbells, weight that represents real effort.

Two: eat at least 1,000 mg of calcium per day, preferably from varied food, dairy, fish with bones, nuts, leafy greens. From October through March, add 1,000-2,000 IU of vitamin D per day.

Three: if you carry risk factors, whether menopause, family history, low weight, smoking, or prolonged corticosteroid use, ask your doctor for a DEXA, because early prevention is far more effective than late treatment.

Strong bones matter most when you never hit the floor in the first place. More on that here: Balance and ageing well: why strength helps in your next decades.

Hold those three things for years and you arrive at 70 with bones that can take a fall on the sidewalk without breaking. Over time, that's the difference between staying autonomous and depending on other people. It sounds dramatic, and it is exactly what happens: hip fractures after 75 are one of the main causes of lost autonomy and early mortality. They get prevented with things within anyone's reach, food, sun, and gym.

You can put all of this into practice on your own. But if you have been circling the same point for a while, a personal trainer on the Costa del Sol can spare you a lot of trial and error. You will know if that is your case.