Our Bone Health
With the popularity of celebrity and social media fuelled diets, a worrying byproduct is that eating patterns may lead to a decrease in the intake of some essential nutrients, which in turn impacts our bone health. One of these nutients, essential to bone health, is calcium. Studies have shown that less than half Australian women meet the daily recommended requirement of calcium.
There is a common misconception that eliminating the dairy food group can assist with weight loss. If there are no medical reasons for doing so, the reality of this is that deficiencies in nutrients such as calcium can lead to a compromise in bone health both now and into the future.
Osteoporosis is a condition in which the bones become brittle and can lead to an increased likelihood of bone fractures. It refers to a loss of bone density where there has been a steady loss of calcium from the bones over a long period of time.
Osteoporosis affects 60% of women over the age of 60 and is a major public health problem.
Laying the foundations
Age related diseases like osteoporosis can be avoided if we lay good foundations early in life and continue them well into our later years.
Our adolescent years are massively important in laying down adequate bone density that will serve us well into our later years. During this time bone is continually resorbing and forming. The rate of formation is greater than resorption which means we need to maximize this process by making sure calcium intake is adequate.
Up to 40% of peak bone mass is laid down in the teenage years so it’s vital that our young people get adequate calcium and vitamin D and engage themselves in activities that will assist with bone building.
By our 20’s the body has achieved peak bone mass and by the age of about 35 we gradually start to lose bone density so if we don’t invest early (into the bone bank) we will be living a large portion of our lives with poor bone density and at greater risk of developing osteoporosis.
Calcium is an essential nutrient. It’s role extends beyond formation of bones and teeth. It is also essential for muscle contraction and other metabolic processes. If calcium is in short supply for these processes your body will withdraw calcium from your ‘bone bank’ for use where it is needed.
Calcium requirements are highest during the teenage years, pregnancy, lactating and elderly women.
Calcium consumption has been shown to be low in teenage girls with the worry being that popular diets tend to eliminate the dairy food group altogether.
One of the trends girls are experimenting with is “going vegan”. While a vegan diet can be a very healthy one, its important to know how to substitute foods that may omit essential nutrients by avoiding food groups such as dairy.
Pregnancy and lactation
Calcium absorption increases during pregnancy so there is no dramatic increase in the requirement for calcium during this time.
Women also produce more oestrogen during pregnancy which helps protect bones.
Any bone mass lost during pregnancy and lactation is usually restored within the months following birth or weaning of baby.
From about 45 years of age bone loss increases to 1 – 2% per year and up to 2 – 4% at the onset of menopause. This is due to the decrease in oestrogen which is a bone protective hormone. Post-menopausal women therefore have a greater need for calcium.
1 – 3 500mg/day
4 – 8 700 mg/day
9 – 11 1000mg.day
12 – 18 1300mg/day
19 – 50 1000mg/day
Women 50+ 1300mg/day
It is recommended to have 3 serves per day of foods that contain easily absorbed calcium.
Where to get Calcium
The best sources of calcium come from dairy foods as these are the most easily absorbed. Good sources:
- Milk, cheese and yoghurt
- Bones of fish eg. tinned sardines and salmon.
- Green leafy vegetables eg. Broccoli, bok choy (absorption from these sources is poor)
- Nuts, seeds.
For those who are lactose intolerant or vegan there are replacement options available in the form of fortified milk alternatives and cereals.
Some factors are also known to inhibit calcium absorption:
- foods high in phytates, eg. Cereals
- Foods containing oxalates, eg spinach
- Low vitamin D
- High sodium intake
- Certain medical conditions and medications.
Role of Vitamin D (Calcium’s BFF!)
Vitamin D is essential for the effective absorption of calcium from the small intestine.
The main form of vitamin D comes from sunlight and a much smaller portion from some foods. Once metabolized into an active form it can aid in the formation of bone.
Vitamin D is particularly important during pregnancy and in menopausal women. Deficiency during pregnancy can leave newborn babies deficient due to lack exposure to sunlight in the early postnatal period.
The elderly may need extra vitamin D in the form of supplements to aid calcium absorption and maintain bone mass that can deteriorate during menopause.
Dietary sources of vitamin D include salmon, tuna, eggs, mushrooms that have been exposed to UV light and foods fortified with vitamin D eg. Margarine.
Role of exercise in preventing osteoporosis
Regular physical activity can play an important role in maintaining healthy bones. Exercise exerts stress on the bone to generate small electrical currents which stimulate mineralization of bone.
Exercise is important at all stages of life but research has shown that children who participate in weight bearing exercise that is medium to high impact have higher bone density compared to less active children. Maximising bone strength early in life can minimize the effects of bone loss later in life where maintenance then becomes important.
There are specific types of exercise that have a positive effect on bone health:
- Weight bearing: brisk walking, jogging, hiking, stair climbing, basketball etc.
- Resistance training: Lifting weights that are progressively more challenging over time. (Australia’s physical activity guidelines recommend muscle strengthening activities on at least 2 days each week.) Moderate to high impact activities, especially short bursts of high intensity movements are highly beneficial: eg. Dancing, basketball/netball, tennis, skipping.
- Variety: Engaging in a variety of exercises will help to challenge bones and muscles on a different level.
- Balance and Mobility: Exercises that improve balance and mobility are also important as they can help prevent falls that can lead to fractures later in life.
As for the weight loss theory, studies have shown that dairy is not the bad guy. With it’s high protein content dairy foods can keep you feeling fuller for longer and therefore keeping the munchies at bay. The protein also helps to build and maintain muscle while the calcium can help reduce the amount of fat absorbed by the body.
There is so much to love about dairy foods for good health. So unless you are unable to consume it due to medical reasons don’t be afraid to include it in a balanced diet.
Wishing you great health and strong bones!
Donna is a trained Nutritionist who runs and owns mishfit Geelong
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