Vitamins and Minerals do I need to supplement? Part Two - Calcium
5th April 2011 By: 14310
This nutrition article looks at some of the key minerals of importance for active women, in particular, iron and calcium.

You will remember in our last nutrition article, we discussed the importance of individual vitamins in an active person and whether supplementation is necessary. As promised we will go onto look at some of the key minerals of importance for active women, in particular, iron and calcium. Iron plays an important role in transporting oxygen around the body and iron deficiency can impair performance, and we will focus on this in our next article. In the present article, we will concentrate on the importance of calcium for active women, which plays a critical role in bone formation and maintenance, and inadequate intake can result in conditions such as osteoporosis.

The nuts and bolts: Calcium

Almost all of our body’s calcium is stored in bones (and teeth). The remainder (about 1%), plays a small, yet extremely vital role in our bodies tissues including;

  • Proper muscle function (the heart is a pretty important muscle don’t forget!)
  • Blood clotting
  • Nerve impulse transmission and,
  • Blood pressure regulation

The balance of calcium in the body is kept constant by a symbiotic relationship between the calcium in our bones and bloodstream. Plasma levels of calcium (i.e. the calcium in our blood stream) must remain at the right level for all of those vital functions listed above to occur. If plasma calcium levels drop as a result of not enough being taken from food, the body has no choice but to steal some calcium out of our bones to top up the bloodstream.

Bones are not a fixed entity and daily, they fluctuate between being manufactured and broken down and being remodelled. From the time of birth, in most women, the bone production is greater than the breakdown and peak bone mass is usually reached around the age of 30 years. After this time, generally the breakdown of the bones occurs at a greater rate than its re-formation, and as a result, bones become weaker. If bones are losing additional calcium in order to top up the levels in our bloodstream, this can contribute to osteoporosis. Osteoporosis is a condition where bones become brittle and weak as a result of bones breaking down more quickly than they can be rebuilt. Women who have experienced menopause are also at greater risk of osteoporosis due to the drop in hormones oestrogen and progesterone which prevent bone loss and promote bone production respectively. It is important therefore that calcium intake is adequate to achieve a good peak bone mass up to the age of 30, and then maintained thereafter as the regenerative bone formation slows.

Exercise is also important for maintaining good bone health. Weight bearing exercise such as walking and running and strength training both stimulate bone growth by putting load onto the skeleton which adapts and strengthens bones. Most golfers reading this article are no doubt undertaking ample weight bearing exercise, therefore we will concentrate the remainder of this article on discussing ensuring an adequate intake of calcium in the diet.

Many women don’t consume adequate amounts of calcium due a low intake of calcium containing foods, in particular, dairy foods. For example, in Australia, it is estimated that the diet of 60% of females is inadequate.

In Australia, the estimated average requirements for calcium for women throughout the lifecycle vary and are as follows;

Life stage 

Calcium requirement 

Girls and Adolescents


Women (menstruating)






Women (post menopause)


The best sources of calcium are dairy foods. Not only are dairy foods rich in calcium, but the naturally occurring sugar in milk products, lactose, assists with calcium’s absorption. The table below gives an idea of the calcium content of a range of foods.

Food source 

Approx calcium content/serve 

Serve Size 

Excellent sources 



Milk (regular or reduced fat)



Soy alternative drink






Yoghurt – plain, flavoured, regular or low fat



Good sources 



Cottage cheese



Processed cheese



Ice cream






Salmon (edible bones)



Moderate Sources 






Sesame Seeds



Soy drink (not fortified with calcium



Spinach, Broccoli, cabbage


½ Cup

Dried Figs


2 whole




Some women may avoid dairy due to underlying conditions such as milk protein allergies or lactose intolerance, or due to the belief that dairy foods contribute to weight gain or high cholesterol. For those with allergies and intolerances, calcium fortified milk substitutes are a good option and supplementation may be necessary (more on supplements later). Dairy foods are an excellent source of protein, calcium and low GI carbohydrates. Low fat version contain all of the above, just minus the fat, so can, and should be included as part of any balanced diet and when consumed in the required amount, shouldn’t contribute to weight gain. In many cases the most kilojoule/calorie efficient way to consume the required calcium is in fact via reduced or low fat dairy foods.

Take the milk versus almonds for example;

  • 1 Cup skim milk = 435kJ (100cals) and 0.3g fat to achieve 300mg calcium.
  • 1 Cup (100g) almonds = 2590kJ (616cals) and 55.2g fat to achieve 300mg calcium.

For those who cannot consume these foods regularly and in the required amounts, may need to consider a supplement. Calcium carbonate and calcium citrate are considered superior supplemental forms of calcium. A good idea is to check the “pure” calcium content of your supplement. If in doubt, talk to your Sports Dietitian or Sports Doctor about which supplement might suit your needs best.

Top tips for optimal calcium intake and absorption

  1. Where possible, consume 3 serves of low fat dairy foods daily.
  2. A diet high in salt can make bone loss occur more quickly. The average daily salt intake is 2000mg (although many have many more). Every 2000mg of sodium removed by the kidneys in urine, takes 60mg of calcium with it, so try to minimise your salt intake across the day.
  3. Caffeine acts as a diuretic, and can therefore flush more calcium through the kidneys
  4. Vitamin D is important for the absorption of calcium. 15-20mins of sunshine x 3 days per week should be plenty, so most golfers should have this covered.
  5. Carbonated drinks may play a role in calcium loss from bones, particularly in adolescents, so don’t go overboard with these drinks.
  6. The magnesium and potassium found in fruits and vegetables also contribute to good bone health.
  7. If taking calcium supplements, take them in the evening as uptake peaks at night time.
  8. If you also take an iron supplement, take this at a different time of day as they tend to compete for absorption.

Until next time, keep calcium on your radar and stay tuned - next up, “Iron and the Female Athlete”!

Kellie Hogan 

Dietitian/Nutritionist APD

Accredited Sports Dietitan 

B Hlth Sci. (Nutr&Diet) (Hons)

Grad Dip. Sports Nutrition (IOC)(Hons) 

Article from Ladies European Tour:
Published: 5/04/2011

© 2013 Ladies European Tour