Doctor, is it true that

Is swimming in the sea good for your bones? Here’s what the science says

The team of doctors and fact-checking experts from the National Medical Association addresses the main health concerns

24 June 2026

Italy, Apulia, Mattinata, Mattinatella beach Valletta Vittorio / AGF

4' min read

Translated by AI

Versione italiana

Key points

Is it true that the sun is good for your bones?
Is swimming in the sea good exercise for your bones?
What specific steps should I take to protect my bones?

4' min read

Translated by AI

Versione italiana

Summer takes many of us to the seaside in the hope of a bit of relaxation, and often with the belief that the sun, salt and sea water are good for ‘our bones’. There is some truth in this belief, but the reality, as always, is far more complex than one might think. Whilst moderate sun exposure, exercise and a balanced diet are definite allies of bone health, none of these factors on its own is sufficient to protect bones over the long term. So let’s find out together what the science has to say.

Is it true that the sun is good for your bones?

Yes, but with some important clarifications. When the skin is exposed to the sun’s ultraviolet B rays, it produces vitamin D, a substance essential for absorbing calcium in the gut and incorporating it into the bones. Vitamin D is, in fact, the main way in which our body obtains this nutrient: diet alone covers only a small proportion of our requirements. The International Osteoporosis Foundation recommends daily exposure of the hands, face and arms for around 10–15 minutes, which is sufficient for most people during non-peak daylight hours. However, many factors influence the amount of vitamin D produced: the time of day, the season, latitude, age, the area of skin exposed, and skin type. Older people, for example, produce less vitamin D than younger people for the same level of exposure.

It should be emphasised that vitamin D supplementation alone is not sufficient to prevent fractures. A systematic review from the Cochrane Library, which analysed 53 clinical trials involving around 92,000 people, concluded that it is the combination of vitamin D and calcium, not vitamin D alone, that modestly reduces the risk of hip fractures and other types of fractures in older people. The evidence regarding vitamin D supplementation in the absence of adequate calcium is, however, far less convincing. This is an issue worth clarifying: we have also discussed it in the factsheet ‘Does vitamin D help prevent fractures?’, in which we explain why vitamin D supplementation on its own has much weaker evidence of effectiveness than is commonly thought, and why lifestyle and a varied diet remain the most robust strategy.

What about sea water? Does it have any direct effect on the bones?

There is no robust scientific evidence that bathing in seawater has a direct effect on bone density or on the prevention of osteoporosis. Thalassotherapy – that is, the therapeutic use of the marine environment – has been studied primarily for its potential applications in treating certain skin conditions such as psoriasis and rheumatic disorders such as fibromyalgia. A narrative review from 2025 published in the International Journal of Biometeorology analysed 14 studies on the subject and concluded that the evidence remains limited and that higher-quality research is needed, particularly to assess the effects on the musculoskeletal system.

There is therefore currently no controlled study of sufficient quality to demonstrate that swimming in the sea or bathing in salt water directly improves bone health. Seawater does not contain minerals in quantities sufficient to affect bone metabolism in a way that can be measured simply through bathing.

Is swimming in the sea good exercise for your bones?

Swimming is an excellent form of exercise for the heart and muscles, but it is not the best way to strengthen bones. The reason is physical: in water, the body is supported by buoyancy and does not have to work against the force of gravity. It is precisely this mechanical load that stimulates the bones to become denser and stronger.

A 2023 meta-analysis published in Frontiers in Physiology analysed studies on aquatic exercise and found positive effects on bone mineral density in the lumbar spine and the femoral neck compared with those who do not engage in any physical activity. However, these effects are less pronounced than those achieved through land-based exercises that involve actual weight-bearing, such as walking, climbing stairs, running or dancing. Swimming should therefore ideally be combined with land-based physical activities to protect bones effectively.

That said, exercising in water remains a valid option for those with joint problems, balance issues or a fear of falling – conditions in which the risk of fractures is already high. In such cases, moving in water is certainly better than not moving at all, and can help to maintain bone mass and muscle strength.

What specific steps should I take to protect my bones?

Bone health is built up over time through a combination of factors. The Istituto Superiore di Sanità points out that regular exercise is essential, and that adults should engage in at least 150 minutes of moderate-intensity aerobic activity per week. To be effective for bone health, however, exercise must involve a mechanical load – in other words, the body must work against gravity. Brisk walking, climbing stairs, dancing or doing gymnastics are more beneficial for the bones than swimming.

When it comes to diet, calcium and vitamin D are the key nutrients. Calcium is found mainly in dairy products, green leafy vegetables and fish with bones, such as sardines. Vitamin D is found in significant quantities in only a few foods – such as oily fish and egg yolks – but the main source remains moderate exposure to sunlight. Smoking and excessive alcohol consumption, on the other hand, damage the bones and should be avoided.

It is worth noting that the osteoporosis is not harmful in itself: the real problem is fractures, and these almost always occur as a result of a fall. We discussed this in the factsheet ‘Do we all have a bit of osteoporosis?’, which explains why preventing falls – through simple precautions at home, regular exercise and eye tests – is often more important than medication.

If you have any concerns about your bone health or belong to a high-risk group – such as post-menopausal women, older people or those with a family history of osteoporosis – it is important to discuss this with your GP.

Read the full article on the dottoremaeveroche website, run by Fnomceo