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A Key Nutrient Endurance Athletes Need Every Day: Calcium

May 06, 2022

A Key Nutrient Endurance Athletes Need Every Day: Calcium

Most people understand that we need calcium for building and maintaining strong bones and strong teeth. But we also need calcium for:

  • Healthy muscle contraction, including the heart
  • Nerve impulses and transmission of messages
  • enzyme function
  • blood clotting

Where does the body get Calcium from?

Our body has two main sources of calcium – the food we eat and our bones.

99% of the body’s calcium is found in the bones, while a small amount is dissolved in the blood.

This blood calcium is essential for the healthy functioning of the heart, muscles, blood and nerves and is tightly regulated.

Bones act like a calcium bank. When we don't get enough calcium from our food, our body withdraws from that calcium bank (held in our bones) to keep our blood level within a certain tight control. If the balance gets tipped too far in the direction where we're withdrawing more calcium from our bones than we are depositing through our diet, over the long term, bone density gradually declines, increasing the risk of osteoporosis and fractures.  

The importance of strong bones in Triathlon

We reach our peak bone mass in our early 20s. After that, it maintains itself until we hit menopause age as a female, and around 70 our fracture risk increases as a male. It's not a slow, steady decline as we get older because we can't build them up any stronger than when it peaks in our early 20s.  

Having really strong bones is super important as a triathlete when we're pounding the pavement – to avoid breaks and stress fractures.  So we need to make sure from our early 20s that we are maintaining our bones - every single day!

On our recent Triathlon Nutrition Academy Podcast Episode 40 - A Key Nutrient Endurance Athletes Need Every Day – Calcium, we covered all things Calcium.

How much Calcium do I need? 

Calcium requirements vary throughout different life stages. Requirements are higher in the following groups: 

  • Teenagers, pregnant and breastfeeding individuals to support increased growth
  • A woman going through menopause where there is more rapid bone loss
  • Older adults - as calcium is not as absorbed as effectively in the intestine and more can be lost through the kidneys.

Adults 19-50 years need ~1000mg/day 
Unless you’re older or younger and still growing

Where do you get Calcium from in your diet?

  • Dairy
  • Green leafy vegetables
  • Soy and tofu
  • Fish (particularly the bones e.g. tinned tuna)
  • Nuts & seeds
  • Calcium-fortified foods

Not all of the Calcium we consume is absorbed

Blockers/inhibitors include:

  • Caffeine intake can increase calcium excretion. Avoid excessive intake of > 4 caffeine drinks per day
  • Alcohol intake and smoking can lower calcium absorption
  • Vitamin D deficiency or low levels can limit calcium absorption
  • Calcium and vitamin D work together to protect your bones—calcium helps build and maintain bones, while vitamin D helps your body effectively absorb calcium in the gut.  We need the Hormone Calcitriol (active Vitamin D) 
  • So even if you're taking in enough calcium, it could be going to waste if you're deficient in vitamin D
  • Calcium consumed at the same time as iron-rich foods are less absorbed - mechanism in the gut and something in the bloodstream that blocks absorption. Small amounts of 50mg seem OK, larger amounts of 300-600ml are more inhibitory
  • High salt (sodium) intake can increase calcium excretion. Aim to have <2300mg sodium or 1 tsp salt per day

As a triathlete who needs strong bones – Calcium is an important nutrient to keep on top of - particularly if you don’t consume normal dairy – which has the highest sources of Calcium.

There is a range of other foods that do contain calcium – but you need to make sure you’re getting enough every day. And if taking milk substitutes, make sure they contain the right amount of calcium.

Reading labels is one of the things that we go through inside the Triathlon Nutrition Academy - so you know exactly what you're looking for. We also cover on all the essential minerals as well as your nutritional needs throughout the program so you know how to make sure you’re getting exactly what you need as a triathlete to become supercharged!

Make sure you take a listen to our podcast episode on the importance of calcium, check out the Triathlon Nutrition Academy and join the waitlist for the next intake in September.

And between now and then, think about how much calcium you're getting in your diet every day. Even keep a checklist and start to tally up how much you're getting compared to how much you need. Because it's so important that, as an endurance athlete, you do that. 


If you’re interested in joining the Triathlon Nutrition Academy, pop your name on the waitlist NOW | Join the TNA Waitlist

If you are looking for a Sports Dietitian and want to learn more about working with me, click HERE to see what I offer for private, 1 on 1 consultation.




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