Bone health: Importance of protein for bones

Most of us realise protein is important for strong healthy muscles – after all, athletes and bodybuilders don’t spend all that money on protein bars and shakes for no good reason. Less well known, however, is how important protein is for bone health too.
 
The International Osteoporosis Foundation says adequate dietary protein is essential for optimal bone mass gain during growth and also for preserving bone and muscle mass with ageing (i). Scientists even claim protein is as essential as calcium and vitamin D for bone health as well as for the prevention of osteoporosis, the medical condition that reduces bone density, causing weakened bones and an increased risk of fractures (ii).
 
Protein is thought to be particularly beneficial for older people too. That’s because bone density naturally declines as you get older – yet many older people may be at risk of not getting enough protein in their diet. Indeed, researchers have found people who eat more protein tend to have better bone density as they get older, which means they may also have a lower risk of osteoporosis and fractures (iii). They also found those who eat the least protein had the greatest amount of bone loss.
    

What are bones made of?

It shouldn’t be a surprise that protein is good for bone health since bones are made up of an organic protein matrix, 90 per cent of which is a protein called collagen (iv). This matrix – where collagen fibres twist around each other to provide the internal structure of bones – comprises around 35 per cent of bone tissue. The rest of your bone tissue is made of bone minerals, including calcium and phosphorus. These minerals are deposited on the collagen fibres, providing your bones with strength and hardness.
 
Bones continue to renew themselves throughout life (a process called remodelling), with old bone tissue being broken down and new tissue forming. Three types of bone cells are involved in this process:
 

1. Osteoblasts: these make new bone and help repair bone damage

2. Osteocytes: these are mature bone cells that help with new bone formation

3. Osteoclasts: these cells are involved in breaking down bone, as well as helping to shape and sculpt bone

 
However, as you age, old bone tissue still gets broken down but less new bone is formed to replace it. This is why it’s natural for bones to lose density with ageing, with women losing bone density at a younger age than men thanks to the fact that levels of the bone-protecting hormone oestrogen drop dramatically during the menopause.
 
But there are things you can do to slow down this process and help keep your bones stronger for longer, one of which is to make sure you get plenty of protein in your diet.

 

How does protein affect bone health? 

There are a few different ways in which protein is thought to benefit bone health:
 

• It provides the amino acids your body needs to build and maintain bone tissue

• It increases the production of a hormone called insulin-like growth factor-1 (IGF-1), which promotes bone growth and remodelling as well as increased muscle mass 

• IGF-1 is also thought to boost the absorption of calcium from food and supplements in the gut

• Protein suppresses the production of parathyroid hormone, large levels of which can trigger the release of calcium from bones into the bloodstream (if your parathyroid gland makes too much parathyroid hormone, the condition is called hyperparathyroid disease or hyperparathyroidism)

• It improves muscle strength and mass, which are positively associated with bone density (muscle weakness, on the other hand, has been linked with an increased risk of falling, which can in turn increase the risk of fracture (v))

 

Does a high protein diet have side effects for bones?

Years ago, scientists used to think that high-protein diets – particularly diets high in animal protein – were bad for bone health. The idea behind this thinking has been called the acid-base theory.
 
This is how the theory works: when dietary sulphur amino acids in protein are broken down in the body during digestion they produce acid, which can change the pH of the blood and make it more acidic. The way the body responds when the blood’s pH becomes too acidic is to use calcium to bring the blood pH back to normal, as calcium helps to neutralise excess acid. The body does this by taking calcium from the bones (bones store calcium and release some of it into the bloodstream when it’s needed by other parts of the body). This then increases the amount of calcium excreted in urine (hypercalciuria). So scientists used to think that, over time, this loss of calcium would weaken bones and lead to osteoporosis.
 
However thanks to modern science this idea is now outdated. Instead of being damaging to bone health, high protein diets are now accepted as beneficial to bone. Some scientists now believe the accepted loss of calcium in urine caused by high protein diets may be offset by the increased amount of calcium absorbed. Experts also believe that, instead of advising against eating high levels of protein, the emphasis should be on encouraging people to eat more fruit and vegetables because of their alkalinising effects on the body (vi). 
 

What protein is good for bones?

Meanwhile researchers have also more recently discovered there’s no evidence to suggest protein from animal sources has any more of a detrimental effect on bone health than that from plant sources (vii). Others have suggested cereal foods contain substances that can also lead to increased acidity, and that they may produce just as much acid during digestion as animal proteins – for instance, oatmeal, walnuts and whole wheat may produce more acidity than chicken, beef and cheddar cheese (viii).
 
In more recent years experts have also suggested that the current guidelines on protein intake may need to be higher to take fuller advantage of protein’s effect on bone health, particularly in older people (ix), and that protein intakes above the current recommended daily amount may help prevent hip fractures and bone density loss (x)
 
Plus there’s evidence that while protein-rich diets are now considered beneficial for adult bone health, they may not be effective unless you eat adequate levels of calcium too (xi). On the other hand, scientists from the University of Surrey have discovered increasing the amount of protein you eat may not have any extra benefit for your bones if you’re a healthy adult and you already have good levels of protein in your diet – but any extra protein doesn’t do your bones any harm (xii)
 

How much protein do you need a day?

The current UK reference nutrient intake (RNI) for protein for adults is 0.75g protein per kilogram of body weight per day. For men of average body weight this works out as 56g per day, and for women of average body weight 45g per day. According to the British Nutrition Foundation, average daily intakes of protein in the UK are 76g for adults aged 19 - 64 years, and 67g for adults aged 65 years and older (xiii).
 
NHS experts, meanwhile, say the amount of protein you need changes throughout your life, and that older people may require more protein to reduce their risk of losing muscle mass – as much as 1 - 1.5g of protein per kilogram of body weight each day (xiv). You may also need up to 2g protein per kilogram of body weight per day if you have a severe illness.
 

What are the best sources of protein?

The top sources of protein in the UK are meat and meat products – with chicken and turkey alone contributing 16 per cent to protein intakes – as well as cereals and cereal products and milk and milk products (xiii). Besides these, good sources include fish, eggs, nuts, soya, beans, peas and lentils. Cereals and grains, while they may be popular protein sources, contain smaller amounts.
 
Here’s a quick guide to approximately how much protein can be found in some common foods (xiv):

 

Food	Protein (g)
140g beef mince	28g
180g battered cod	25g
100g drained tinned tuna in oil	25g
100g salmon	23g
Lamb chop (70g)	20g
80g tofu	19g
100g Quorn	13g
50g roasted peanuts	13g
40g chicken breast (one slice)	10.9g
40g Cheddar cheese	10g
Half a pint of cow’s milk	10g
150g baked beans	8g
1 egg	7g
125g yoghurt	7g
25g peanut butter	6g
1 tablespoon green lentils	4g

As a general rule of thumb, to make sure you’re getting enough protein try to fill at least a quarter of your plate with protein foods at every meal. Also choose protein-rich foods as snacks – a palmful of nuts or seeds, for instance, instead of a packet of crisps; or a pot of Greek or Skyr yoghurt instead of a couple of biscuits.
 

Supplements and vitamins for bone health 

As well as protein, it’s important to include other bone-supporting nutrients in your diet, including:
 

Calcium

It’s well known that we need calcium for healthy bones. However many people may not be getting enough calcium in their diets. You need at least 700mg of calcium a day if you’re an adult, which for some people may not be that easy to achieve through food (good sources of calcium include milk and other dairy foods, foods fortified with calcium, fish that includes edible bones and some green leafy vegetables such as kale). Calcium supplements are also widely available, including single supplements, multivitamin and mineral formulas, and multi-nutrient products designed for bone health.
 

Vitamin D

Vitamin D is also important as it helps your body to absorb calcium from your food or supplements. Indeed, studies suggest taking vitamin D with calcium may help prevent bone loss (xv).
 
The problem is that many people living in the UK and other northern hemisphere countries are at risk of vitamin D deficiency during certain times of the year, since skin exposure to sunlight is our main source. This is why the Department of Health and Social Care advises everyone in the UK to consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter months (those who are at high risk of not getting enough vitamin D during the spring and summer are advised to take a supplement all year round too) (xvi).
 
The recommended form of vitamin D is vitamin D3 or cholecalciferol, as it’s the natural form of vitamin D the body makes when it’s exposed to sunlight. Vitamin D3 supplements are available in tablet form, plus you can now get them in veggie-friendly drops too. Most vitamin D3 supplements, however, are made from the fat of lamb’s wool, which means they’re unsuitable for vegans. The good news is that vegan vitamin D3 supplements sourced from lichen are becoming more widely available.
 

Vitamin K

This may not be as well-known as a bone health nutrient as calcium and vitamin D, but vitamin K is also needed for making important bone proteins. Vitamin K also works alongside calcium and vitamin D to keep your bones strong: while vitamin D helps your body absorb calcium, vitamin K helps calcium to get where it’s needed (that is, into your bones and teeth instead of your soft tissues where it can cause problems). Studies that investigate the role of vitamin K in human (rather than animal) bone health are still at a relatively early stage, but some have linked poor bone health with low vitamin K levels (xvii), with others have found the amount of vitamin K in people’s diet and their bone mineral density are related (xviii).
 
A study that looked at some of the data from the large-scale Nurses’ Health Study, meanwhile, suggests women who consume at least 110 micrograms of vitamin K each day are 30 per cent less likely to break their hip than those who eat less (xix). The researchers indeed claim low intakes of vitamin K may increase the risk of hip fracture in women.
 
Scientists analysing information from another large-scale study – the Framingham Heart Study – also found a link between vitamin K intake and the risk of hip fracture, not just in women but in men too (xx).
 
Vitamin K is found in plant foods such as leafy greens as well as in animal-sourced foods and fermented foods. Find out more about vitamin K and the foods that contain it in Bone health: the importance of vitamin K. You can also get vitamin K in supplement form singly or as part of a good multivitamin and mineral supplement or a multi-nutrient bone health supplement.
 

Magnesium for bones

Magnesium is another important nutrient for bone health as it helps keep bones hard and rigid. Indeed, 70 per cent of the body’s magnesium is stored in the bones and teeth. Magnesium also helps convert vitamin D into the form that boosts calcium absorption in the body. Many people, however, may not be getting enough magnesium in their diet (sources include nuts, seeds, green leafy veg, whole grains, beans and lentils).
 
If you’re looking for a magnesium supplement, choose a form of magnesium that’s absorbed more readily than others, such as magnesium citrate.
 

Zinc 

The mineral zinc has also been shown to play an essential role in bone metabolism and mineralisation (xxi), with scientists claiming it’s an essential mineral required for normal skeletal growth and that it may also be able to promote bone regeneration (xxii). Like magnesium, the citrate form of zinc is thought to be better absorbed by the body than other forms. You can also try getting more zinc-rich foods in your diet such as dairy foods, shellfish, meat, bread and wheatgerm.
 

Vitamin C

Vitamin C is important for bones as it contributes to normal collagen formation. More recently, however, researchers have discovered vitamin C has other functions that may help keep bones strong too. Some have claimed the ways in which vitamin C affect how our genes work are central to bone formation, and that it may help prevent common bone-degenerating conditions (xxiii). Vitamin C is found in a wide variety of fruit and vegetables, but a good-quality supplement can help make sure you’re getting your fair share.
 

What is the best exercise for bone health? 

Staying active – especially by taking part in certain types of activities – is another important way of helping prevent or reduce bone density decline. According to the Royal Osteoporosis Society, the most effective way to keep your bones strong through exercise is to combine weight-bearing exercise with impact and muscle strengthening exercise (xxiv).
 

Osteoporosis exercises:

 

• Low-impact activities include walking, marching and stair climbing.

• Moderate-impact activities include skipping, hopping, jogging, running, team and racket sports and Highland dancing.

• High-impact activities – the most effective for improving bone density – include star jumps, tuck jumps, track events, volleyball and basketball.

Meanwhile muscle strengthening exercise includes moves such as squats, lunges, leg presses, chest presses, dead lifts and bicep curls.

Whatever exercise you do, start slowly and build up your fitness levels gradually if you haven’t been very active lately. Always speak to your GP before starting any new exercise regime if you have a medical condition.
 

Want to find out more?

Discover more details of ways to keep your bones healthy by reading some of the other articles in the bone health section of our pharmacy health library. Meanwhile you can also read up about the most common bone health condition – including what you could do to help prevent it – in our guide to osteoporosis
 

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Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.

 

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