Calcium – Making our body stronger by eating seaweed

An old favorite and probably one of the most well-known essential nutrients of all time, calcium is needed to maintain bone strength and carry out many important functions.

And there is a reason for its hype. Many research studies have demonstrated links between low calcium intake and diseases like osteoporosis, arterial hypertension and colon cancer.

 

Recommended Dietary Allowance and Disease Prevention

Happy bones are full of calcium.

This is why the average recommended dietary allowance of calcium is about 900 mg per day for adults, which rises up to 1200 mg a day for adolescents and the elderly (Berkey, et al., 2005).

Osteoporosis, arterial hypertension and colon cancer, as mentioned above, have many causes, but the scientific community now recognizes that eating your daily dose of calcium helps prevent them (Berkey, et al., 2005).

Calcium Intake during Pregnancy

Systematic reviews have looked into calcium supplementation on a daily basis during pregnancy to determine whether it safely improved maternal and infant outcomes.

After a while of looking at the numbers, the findings revealed that this intervention significantly reduced the risk of pre-eclampsia and high blood pressure (WHO, 2013), which means it reduces the risk of women dying during childbirth.

Right now, about 70% of dietary calcium comes from milk and dairy products. In adults, since they pretend to have a finer palate, calcium comes mainly from cheese.

 

Calcium Bioavailability – What Is It and Why Does It Matter?

Now, the bioavailability of calcium refers to the fraction of calcium that is potentially absorbable from food and incorporated into the body.

Regular milk, for example, has a good bioavailability of calcium. It ranges from around 30 to 35%.

To meet calcium recommendations, the bioavailability of calcium is an important factor to consider beyond simply the calcium content of foods (Guéguen & Pointillart, 2005).

Only a few green vegetables and dried fruits are good sources of calcium. In that sense, they facilitate a 16% of calcium intake. However, generally speaking, plant foods contain a considerable amount of inhibitory substances, such as oxalates and phytates, which prevent the body from absorbing the calcium.

On the contrary, bioavailability is not a problem in seaweeds. Calcium in seaweeds is available as calcium phosphate, which is even more bioavailable than the form of calcium in milk, calcium carbonate.

 

Why Do Oxalates and Phytates Matter?

Oxalates and phytates attach themselves to calcium and form salts that the body cannot dissolve, which decreases calcium absorption.

To see how it works, think of cooked spinach. Popeye’s favorite greens contain 115 mg calcium per serving (let’s say ½ cup). However, only an estimated 5% (6 mg in absolute value) of it is actually absorbed. These numbers are very small when you compare them to the 32% (over 101 mg) of milk’s calcium absorption.

Based on the above, one would have to consume about 8 cups of spinach to obtain the same amount of available calcium found in 1 cup of milk (Caroli, 2011), which is virtually insane as eating 8 cups of anything is pretty much impossible.

 

Calcium in Seaweed

But seaweed is here to help!

It is a good source for calcium, especially for people who cannot consume milk due to intolerance, those who are vegan, and/or those under diet regimes or who cannot consume dairy due to any other reason.

Important minerals, such as calcium, accumulate in seaweeds at much higher levels than in terrestrial foodstuffs.

Depending on the species of seaweed, the calcium content of seaweed can range between 100 to 570 mg per gram. Milk, in comparison, has approximately 115 mg per gram.

However, to this day, the position of health agencies such as the World Health Organization remains that milk is the most economical and effective food for human calcium intake. Ironic, is it not?

 

Seaweeds and Calcium Supplements

Seaweeds are an even better option than calcium supplements. Calcium supplements may actually increase the risk of certain illnesses, such as kidney stone and heart disease (Rajapakse, et al., 2011; MacArtain, et al., 2007).

 

Busting Myths on Calcium

As with many other things these days, there are some myths going around the Internet regarding milk.

Some are interested, for example, in phosphatase when discussing calcium intakes for humans.

An existing argument is that milk loses phosphatase when pasteurized, which makes people question if this could potentially affect the bioavailability of calcium.

However, thorough research on our part has not yet located rigorous scientific support for this idea. To us, this notion sounds like more of a myth. Whatever happens, please do not consume unpasteurized milk; there is a reason why we have been pasteurizing it for so long.

 

References

Berkey, C. S., Rockett, H. R., Willett, W. C., & Colditz, G. A. (2005). Milk, dairy fat, dietary calcium, and weight gain: a longitudinal study of adolescents. Archives of pediatrics & adolescent medicine, 159(6), 543-550. https://jamanetwork.com/journals/jamapediatrics/fullarticle/486041

Caroli A et al. Invited review: Dairy intake and bone health: A viewpoint from the state of the art. J Dairy Sci 2011;94(11):5249-62.

Guéguen, L., & Pointillart, A. (2000). The Bioavailability of Dietary Calcium. Journal of the American College of Nutrition, 19(sup2), 119S–136S. doi:10.1080/07315724.2000.10718083

MacArtain, P., Gill, C. I., Brooks, M., Campbell, R., & Rowland, I. R. (2007). Nutritional value of edible seaweeds. Nutrition reviews, 65(12), 535-543.

Rajapakse, N., & Kim, S. K. (2011). Nutritional and digestive health benefits of seaweed. In Advances in food and nutrition research (Vol. 64, pp. 17-28). Academic Press.

WHO. 2013. Guideline: Calcium supplementation in pregnant women. 

Geneva, World Health Organization.