CALCIUM: HOW MUCH DO YOU NEED AND WHERE DOES IT COME FROM?
Calcium is important in the human body for development of the skeleton. Calcium is stored in the teeth and bones, where it provides strength and structure. It is especially important for children, because their teeth and bones are forming, developing and growing.
Sufficient calcium is vital in order for a person to reach their peak bone mass. This is the maximum ‘strength’ of their bones. It usually peaks at around 25-30 years old and then begins to slowly decline after this. Peak bone mass is determined by genetic factors, but sufficient calcium, vitamin D and physical activity help ensure that it can be reached.
If blood calcium levels fall, the body begins to break down bone to release calcium and ensure blood calcium levels remain steady. Low intakes of calcium and Vitamin D in children can lead to a disease called rickets, where the bones become soft and bendy, and growth can be stunted. In New Zealand, we are seeing increased rates of rickets. Those at higher risk of having children with rickets are those who do not consume dairy products, those who do not have much sun exposure (e.g. housebound or those that cover their skin) and those individuals with darker skin. Low calcium intakes in adults can lead to decreased bone density, increased risk of fractures and falls, as well as osteoporosis. This occurs when the bones become brittle and can break easily. Osteoporosis is one of the major causes of disease among older New Zealanders.
It is important children have adequate calcium intakes because they only have one chance to form their bones and adult teeth. During the growth spurt in adolescent years, calcium requirements are increased to keep up with the rapid bone growth. Postmenopausal women are especially at risk of osteoporosis because less calcium is absorbed due to lower oestrogen levels in the body.
Many individuals are unable to meet their requirements for calcium. A study by the Ministry of Health and the University of Otago study done in 2011 found that as many as 88% of adolescent females and 58% of adolescent males do not meet their respective guidelines for calcium intake.
Calcium is mainly found in milk or milk-based foods, such as cheese, cottage cheese and yogurt. Bread and bread-based dishes can also contribute to the calcium intakes of New Zealand children and adolescents as they are consumed frequently and contain small amounts of calcium through fortification. Smaller amounts of calcium are found in some fish, legumes, nuts and some vegetables such as zucchini or kale. If you cannot tolerate dairy, plant-based sources may be more appropriate.
An adequate intake of Vitamin D is needed to maintain calcium levels in the body. Vitamin D helps the absorption of calcium in the small intestine. Vitamin D levels in New Zealand tend to be lower during the winter and higher in the summer, as majority of Vitamin D comes from the sun. It is found in small amounts in the diet from fish such as tuna, eggs and breakfast cereals with added vitamins, but these levels are quite low. It is important to get out in the sunshine, especially in the winter time. In the summer months, expose your skin to sunlight at the very beginning or the end of the day to avoid burning. Physical activity and weight-bearing exercise, such as running, jumping and changing directions, also helps children and teenagers to develop strong bones for life.
So, to ensure you and your child meet your respective calcium requirements, eat plenty of green vegetables, such as broccoli, have milk or other dairy products such as yoghurt if you can tolerate them and get outside for some exercise or playtime to expose your skin to the sun. This will help ensure your bones become as strong as they can be and reduce the risk of developing osteoporosis later in life.
Ministry of Health, 2006. Nutrient Reference Values for Australia and New Zealand Including Recommended Dietary Intakes. Canberra: National Health and Medical Research Council.
University of Otago and Ministry of Health. 2011. A Focus on Nutrition: Key findings of the 2008/09 New Zealand Adult Nutrition Survey. Wellington: Ministry of Health
Original content from: www.jumpstartnutrition.co.nz