Bones are tissues or a group of cells that make up your skeleton. They support your body and hold you upright. Bones also allow you to move while protecting your organs from injury, for example your ribs protect your heart and lungs, and your skull protects your brain. Furthermore, bones make blood cells called bone marrow, and act as a storehouse for minerals and vitamin D. Some bones even store fat, releasing it when your body needs energy.

Strong bones begin in childhood; however, from the age of 30 your bones gradually decrease in strength and density. Bones can become more prone to facture as we age, and a condition called osteopenia commonly develops in older people. Osteopenia is where the density of the bone decreases but has not become as porous as in osteoporosis. Osteopenia is a warning to take action to improve your bone health as you are at risk of developing osteoporosis. With good habits and awareness, you can maintain strong bones throughout your lives.

How can you keep your bones healthy?

• Avoid bone injuries by wearing the right equipment to protect your bones when doing certain activities. It is important to minimise any risk of fractures, as they can impact on your bone health.
• Exercise is good for bone health as your body respond to exercise by making new bone tissues, which keeps your bones strong. Weightbearing activities such as jogging, dancing, and walking can help.
• Consuming enough vitamin D

Having adequate vitamin D is just as important as having enough calcium because vitamin D helps your body absorb the calcium in the foods you eat. It also plays a role in the growth and maintenance of your skeleton and helps to regulate calcium levels in your blood.

Some foods may contain small amounts of vitamin D, such as oily fish (salmon, tuna, herring, mackerel), liver, egg yolk and selected fortified products such as cereal, yoghurt and milk/milk alternatives. But food alone cannot provide an adequate amount of vitamin D. For Australians, the main source of vitamin D is from exposure to sunlight. Direct sunlight on the skin produces vitamin D. How long you need to spend in the sun is based on the season, your location within Australia, your skin type and the amount of skin exposed. There is a fine line between balancing sun exposure for vitamin D while avoiding damage to your skin and increasing your risk of skin cancer. 

In summer a few minutes mid-morning or mid-afternoon is generally adequate to get vitamin D, while in winter a longer exposure time is needed.

Vitamin D supplements taken over a few months may be advised by your doctor if your levels are low. The dosage will depend on your individual circumstances, such as your level of deficiency and sun exposure. 

Eating well to keep your bones healthy

One of the most important aspects of building and maintaining strong bones is good nutrition. Bones are made of a mineral called calcium phosphate, which is why calcium plays a vital role to keep your bones strong. About 99% of the calcium in the human body is in the bones and teeth. Australian dietary calcium recommendations vary according to age.

Children (1-3 years) – 500mg per day

Children (4-8 years) – 700mg per day

Children (9-11 years) – 1000mg per day

Teenagers (12-18 years) – 1300mg per day

Adults (19 years +) – 1000mg per day

Adults (women 50 years +) – 1300mg per day

Adults (men 70 years +) – 1300mg per day

** Ref Healthy Bone Australia

Calcium-rich foods

• Dairy products such as milk, yoghurt, cheese
• Seafood: oysters, prawns, canned sardines/salmon
• Vegetables: watercress, bok choy, leeks, cucumber, silver beet, Chinese cabbage
• Nuts and seeds: almonds, walnuts, tahini paste, hazelnuts, Brazil nuts
• Fruits: figs, kiwi fruit, dates, orange, strawberries, currant (dried gooseberry), raisins
• Meat: pork chop, chicken
• Others: chickpeas, eggs, calcium set tofu
• Fortified breakfast, milk alternatives (soymilk, almond milk, oat milk, rice milk, etc.)  

Factors that impact on calcium absorption

Not all calcium we consume is absorbed, small amounts are excreted via the body. It is therefore important to consider the following:

Phytates and beans: Although beans are a great source of calcium, magnesium, fibre and other nutrients, they are also high in a substance called phytates. This substance can interfere with the absorption of calcium. Therefore, soaking your beans and draining the water before cooking is important.

Spinach and oxalates: Calcium and oxalates aren’t friends. Spinach is high in both, and the oxalates prevent a lot of the calcium from being absorbed into the body.

Wheat bran: Wheat bran can contain high levels of phytates, which can prevent calcium absorption. However, it is usually only an issue when 100% wheat bran is consumed.

Alcohol: Heavy drinking can lead to bone loss. Follow the Australian alcohol guidelines that specify no more than 10 standard drinks a week, and no more than four standard drinks on any given day (for both healthy men and women).

Caffeine: Caffeine found in coffee, soft drinks, energy drinks, and tea may decrease calcium absorption and contribute to bone loss. Moderation is key!  

Did you know?

• There are 26 bones in the human foot
• The stapes, in the middle ear, is the smallest and lightest bone of the human skeleton
• Bone is a living tissue, where the collagen in bone is constantly renewed and remodel. On average, most of the adult skeleton is replaced around every 10 years.  
• A funny bone is not really a bone. It is actually the ulnar nerve that runs inside of your elbow. Hitting it triggers a tingling, prickly pain.
• Babies have about 300 bones at birth, where they eventually fuse (grow together) to form the 206 bones in adults.  

By Michelle Tong, Accredited Practising Dietitian