What functions do bones serve?
- As a structural framework for tendons to attach to and provide support for soft tissue.
- To protect internal organs from injury e.g. the ribs protect the heart and lungs.
- To assist in movement. The tendons from muscles are attached to the skeleton so movement of the muscle results in movement of the bone and hence movement of the body.
- As a storage depot for many vital minerals the body needs in everyday activities e.g. calcium.
- To produce blood cells. The red bone marrow found in the connective tissue of certain bones is the site of blood cell production.
- As an energy storage site in children. Triglycerides which are a source of energy are stored in the yellow bone marrow
Bones play an important role in our wellbeing and we need to ensure we build strong healthy bones early on in life in order to avoid developing certain disorders, including osteoporosis.
What is osteoporosis?
Osteoporosis is a disease characterised by a thinning and weakening of the bones due to the loss of calcium containing material. This causes the bones to become fragile and be more likely to break from a fall or an injury. The most common fractures are the spine, hip and wrist. There are two major factors that influence the development of osteoporosis.
- Peak bone mass levels that are obtained in early life
- The amount of bone mass lost later in life
Bone mass slowly decreases as we get older. Women are at a greater risk because they have lighter bones and they also experience a drop in oestrogen levels after menopause, which quickens the loss of bone.
What is peak bone mass?
Bone mass is the term used to describe the amount of bone tissue and density that is in a bone. Peak bone mass refers to the highest level of bone mass an individual has at a particular point in their life. Peak bone mass is usually achieved at around age 25 – 30 years. It is therefore important that as much bone mass as possible is laid down before this age so you have as high a bone mass as possible. It is after this age that we begin to lose bone mass at a rate of 1% per year. For women this increases even more once menopause occurs due to the reduction in estrogen.
Why is calcium important?
99% of our body’s calcium is stored in the bones and teeth and 1% is used throughout the body. Calcium is involved in many functions in the body, including; assisting with blood clotting, muscle function, nerve impulses and fluid balance. When the calcium levels in the body drop and not enough is available from food, calcium is taken from the bones.
Good sources of calcium
Good sources of calcium are dairy foods such as milk, yoghurt and cheese. Calcium fortified soymilks are a suitable dairy alterative. Calcium is also found in nuts (particularly almonds, Brazil and hazelnuts), sesame seeds, whole canned fish with edible bones, tofu set with calcium, dried figs and apricots, green vegetables (like bok choy, spinach, broccoli) and dried beans.
To maximise your calcium uptake, try to limit food components that can inhibit calcium absorption such as salty foods (processed meats, crisps, salted nuts and foods preserved in brine or high salt sauces), and caffeine (from tea, cola drinks, coffee and high energy drinks) which will cause more calcium to be lost from the urine. Also be aware that animal protein found in foods such as cheese and milk can cause more calcium to be lost from the body via urine. Try instead to include more plant proteins in your meals (soymilk, legumes and nuts).
What are other things I can do to build strong bones?
Exercise - The best types of exercise for bone strength are weight bearing and strength training. Examples include walking, jogging, tennis, dancing, golf, Pilates and exercises using weights or elastic bands for resistance. Swimming and cycling won’t directly increase your bone strength, as they are examples of non-weight bearing exercises, because your weight is supported (by the bike or the water).
Avoid smoking and alcohol – they are risk factors for developing osteoporosis.
Include foods that contain other bone nutrients - Calcium and vitamin D are important nutrients for bone health but there are some other nutrients that protect the bone also – vitamin K, B, A, magnesium and zinc. To ensure you have a healthy diet with all the nutrients you need base your meals on whole grain breads and cereals, vegetables, legumes (peas, beans and lentils) and fruits. Include some reduced fat dairy products or soy alternatives, eggs, lean meat, skinless chicken, fish, nuts and seeds.
Regular intake of soy foods has been shown to promote healthy bones.
Eat soy – Soy foods are a source of calcium in the diet. Research shows that soy protein can help to conserve calcium levels in the body. Isoflavones, found naturally in soy foods, have been shown to help maintain strong bones through preventing bone loss, stimulating new bone formation and increasing bone mineral density. The combination of soy protein and isoflavones, found in all soy foods, help to maintain healthy bones.