Calcium is vital for bone health, assisting in bone deposition, thereby preventing osteoporosis. It also plays a role in other bodily functions such as nerve transmission and muscle contraction.
1. How much calcium do I need?
Most South Africans only manage to consume 500–600mg/day, meaning that we are falling short of our recommended daily intake for calcium.
2. Do I need to take a calcium supplement?
Consuming calcium-rich foods is the best way to meet your calcium requirements. Only when you are unable to get sufficient calcium from your diet, should you consider supplementing to make up the difference.
Milk and dairy products are a convenient source of bone-healthy vitamins and minerals (calcium, phosphorous and vitamin D). Calcium is however also found in other food sources.
3. How much calcium am I actually absorbing?
When deciding on your preferred source of calcium, you should consider how well calcium is absorbed as well as how much food you need to eat to ensure an adequate calcium intake.
Foods high in fibre can bind calcium, thus decreasing calcium absorption.
While approximately 32% of calcium is absorbed by the body from milk and dairy sources, only 21% is absorbed from almonds (moderate phytate) and only 5% from spinach (high phytate).
A higher percentage of calcium is absorbed from certain vegetables than is from milk:
- 32% from milk
- 61% from broccoli
- 54% from bok choy
- 49% from kale
- 22% from sweet potato
However, it is important to take note of the ease of consumption of adequate quantities of each of these foods to meet you daily requirement.
4. How can I ensure that I’m getting enough calcium from a dairy-free diet?
Although plant foods, such as those described above, have highly available calcium, it occurs in much lower quantities compared to dairy products.
Top tip: To reach a similar amount of calcium as in a 250ml glass of milk, replace with:
- 2.6 cups broccoli
- 2 cups bok choy
- 2.2 cups kale
- 5.9 cups of sweet potato
5. What is the calcium content of various foods?
While every effort should be made to meet your calcium requirement through food sources, if you find that you are constantly falling short, a supplement can be considered.
6. Which supplement is the best to use?
This varies depending on tolerance, convenience, cost and availability. Calcium carbonate is cost effective but should be taken with meals to assist absorption. Calcium citrate, while more expensive, is well absorbed, regardless of meal timing but has a
lower concentration of elemental calcium and consequently more needs to be taken.
Calcium lactate and calcium gluconate are less concentrated forms of calcium and are generally not used for supplementation. In terms of dosage, choose a supplement providing approximately 500mg elemental calcium (elemental calcium is the
calcium that will actually be absorbed). Higher doses could aggravate gastrointestinal (GI) discomfort and GI complaints are the most common adverse effect of taking calcium supplements.
The body also can’t absorb more than 500-600mg of calcium at a time so taking more would be a waste.
National Osteoporosis Foundation South Africa. 2012 statement on calcium. http://osteoporosis.org.za.
National Osteoporosis Foundation South Africa. Calcium supplements. http://osteoporosis.org.za.
McCance & Widdowson (2002) The Composition of Foods Sixth summary edition. Cambridge: Royal Society of Chemistry USDA National Nutrient Database for Standard Reference. https://ndb.nal.usda.gov/ndb/foods
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