Calcium & Health
What is Calcium & What Does it Do?
Calcium is the most abundant mineral in our body. We store most (~99%) of it in our bones and teeth as hydroxyapatite, a large molecule that combines calcium, phosphorus, and oxygen.
The remaining small amount circulates through our body. This circulating calcium plays many important roles, including constricting or relaxing our blood vessels, sending nerve impulses, contracting and relaxing our muscles, and releasing hormones like insulin when they are needed. Calcium even plays several key roles in our blood clotting along with Vitamin K! (1)
Unfortunately, calcium is a nutrient of concern with a significant portion of our population not eating enough.
Calcium Deficiency:
One way we can appreciate how important calcium is for our function is to see what happens when we consume a low calcium diet: our body will take it right out of our bones. We see situations of low calcium in parathyroid disease, chronic kidney disease, low vitamin D, and in alcoholism when the normal absorption and elimination of calcium are no longer working in balance.
“Symptoms of hypocalcemia most commonly include paresthesia, muscle spasms, cramps, tetany [sustained muscle spasms], circumoral [around the mouth] numbness, and seizures.” (2)
A Side-Note on Bone Density:
During the first 30 years of our life, our bodies are busy growing and storing calcium in our bones. By the time we end the third decade of our life, we will have reached our maximum bone density. From this point on, the balance between bone building and breakdown shifts away from building. This is a normal function of our bodies and our bones are constantly changing in response to the physical stressors that are or are not put upon them. This is why exercise, especially weight bearing exercise, is so important to our bone health.
This is also why, when it comes to our bone health, our diet during our youth is even more important than as we age. How much calcium we add to our bones during these earlier building years will determine how well we are set up for our more advanced years. After the age of 30, we can make conscious efforts to maintain our bone density and slow its loss, but we cannot increase that density!
Prevention of Disease:
Osteoporosis:
As you can see from our discussion of bone density, calcium can play a major role in the prevention of osteoporosis when adequate levels are consumed, especially at an early age. This will prevent the reabsorption of stored calcium from the bones in order to keep the body functioning.
Osteoporosis is a major medical issue affecting a significant portion of our population, and is especially prevalent in post-menopausal women. Often there are no preceding symptoms before a bone fracture. Anything we can do to prevent this is important.
If you are over the age of 30, there are actions you can take in addition to maintaining a good diet and adding exercise. I encourage you to visit the NIH overview of osteoporosis (3) to learn more and talk with your doctor about prevention, especially if you have a family history of osteoporosis.
Kidney Stones:
Most kidney stones contain calcium, and it was once thought that reducing calcium in the diet was one way to prevent kidney stones. We now know better. It isn’t the calcium we consume that is the problem with kidney stones, it is the calcium we eliminate through our kidneys, and there are things we can do to reduce this.
Dietarily, we can opt for a low sodium diet, avoid cola and food preservatives, and keep our caffeine intake at 400 mg or less daily, as high levels of each of these substances increase our calcium excretion. Keeping an eye on our kidney health is also important if we are prone to or have a family history of kidney stones, as increased calcium in the urine can be a sign of failing kidney health. (1)
Hypertension is Pregnancy:
Pre-eclampsia and eclampsia are dangerous conditions associated with pregnancy, which can result in maternal and fetal death. Calcium supplementation--or preferably a calcium-rich diet when available--may reduce the incidence of these diseases in pregnancy. (4)
Colorectal Cancer:
Colorectal cancer is cancer found anywhere along the large intestine or rectum. It is the third leading cause of cancer death in the United States. (5) While there isn’t a consensus on how diet can be used to reduce the risk of this cancer specifically, we can work to reduce our oxidative stress, support our methylation pathways, keep our microbiome happy with plenty of fiber, and it appears a diet high in calcium may also be protective. (6)
Lead toxicity:
Lead exposure from gasoline and lead-based paint is becoming less common due to changes in the industries. However, lead exposure from aging pipes remains a real problem, with the EPA estimating around 6-10 million homes in the US remaining at risk. (7) With the current COVID-19 crisis, the CDC believes the problem may be increasing due to fewer children receiving lead screening. (8) News articles seem to pop up regularly showing elevated lead levels in our drinking water. Just today, I needed to edit this article to include a new report on lead contaminated water in my home area. (9)
Lead exposure can lead to long-term, irreversible neurological damage, anemia, kidney disease, damage to reproductive systems, and more. (10)
While not a treatment, calcium can decrease the absorption of lead and reduce the amount of lead stored in the skeleton from circulating. This is in no way a solution to the problem of lead exposure - that is a systemic, infrastructure-level problem - but ensuring adequate levels of calcium in the diet may give some protection.
Calcium Toxicity:
As we have seen in the past, too much of a good thing isn't a good thing. Outside of cancer or hyperparathyroidism, it is difficult to raise blood levels of calcium to dangerous levels, but it is possible. Hypercalcemia is a life threatening condition with symptoms ranging from loss of appetite to coma and death. To avoid reaching these levels, an upper limit (UL) of 2,500mg for adults has been established.
Where to Find Calcium:
Outside of supplements, calcium can be found in many different foods. Some foods are better sources of calcium than others, due to the presence of oxalates or phytates which can interfere with absorption; however, fermentation of these foods breaks down those pesky chemicals and increases the bioavailability of calcium.
Foods particularly rich in calcium include:
Milk and milk-based products
Tofu
Sardines
Beans
Figs
Oranges
If one is going to add a calcium supplement, which may be a good idea if you do not eat dairy products, calcium citrate seems to be the easiest form to absorb and is the best choice for those with low stomach acid.
Applications:
Our takeaways this week are:
Calcium is a very important mineral for our body’s health, and if we don’t eat enough, it will get pulled from our bones, leading to an increased risk of osteoporosis.
Our bone density reaches its peak at age 30, so we need to do all we can to build our bones before this!
Adequate calcium intake is preventative for several different diseases.
Calcium toxicity is a thing, and adults should keep their intake below 2500mg daily to avoid hypercalcemia.
Daily Intake:
The RDA for calcium is 1000 - 1200mg for adults. Older children and adolescents need a bit more at 1300 mg daily. (1)
Medication and Nutrient Interactions:
Calcium interacts with many different substances, so it is often taken away from many medications or supplements including:
Iron
Levothyroxine
Bisphosphonate
Tetracycline
Antiretroviral therapies
And others
Calcium supplementation paired with digoxin may result in increased cardiac arrhythmias. (1)
Acid blocking therapies such as proton pump inhibitors or histamine antagonists can decrease calcium absorption.
Next week:
Next week we will look at our second mineral, Chromium.
To our health!
References:
Higdon, J, “Calcium” Linus Pauling Institute, 2000; last update: 2017; accessed November 22, 2021; https://lpi.oregonstate.edu/mic/minerals/calcium
Fong J, Khan A. Hypocalcemia: updates in diagnosis and management for primary care. Can Fam Physician. 2012;58(2):158-162.
National Institutes of Health, Osteoporosis Overview, accessed November 22, 2021 https://www.bones.nih.gov/health-info/bone/osteoporosis/overview
Sun X, Li H, He X, Li M, Yan P, Xun Y, Lu C, Yang K, Zhang X. The association between calcium supplement and preeclampsia and gestational hypertension: a systematic review and meta-analysis of randomized trials. Hypertens Pregnancy. 2019 May;38(2):129-139. doi: 10.1080/10641955.2019.1593445. Epub 2019 Apr 2. PMID: 30935246.
CDC, “Colorectal Cancer Statistics” accessed November 22, 2021, https://www.cdc.gov/cancer/colorectal/statistics/index.htm
Azeem S, Gillani SW, Siddiqui A, Jandrajupalli SB, Poh V, Syed Sulaiman SA. Diet and Colorectal Cancer Risk in Asia--a Systematic Review. Asian Pac J Cancer Prev. 2015;16(13):5389-96. doi: 10.7314/apjcp.2015.16.13.5389. PMID: 26225683.
US Environmental Protection Agency, Office of Water, “Lead and Copper Rule Revisions White Paper”, October 2016, accessed, Nov 22, 2021https://www.epa.gov/sites/default/files/2016-10/documents/508_lcr_revisions_white_paper_final_10.26.16.pdf
Courtney JG, Chuke SO, Dyke K, et al. Decreases in Young Children Who Received Blood Lead Level Testing During COVID-19 — 34 Jurisdictions, January–May 2020. MMWR Morb Mortal Wkly Rep 2021;70:155–161. DOI: http://dx.doi.org/10.15585/mmwr.mm7005a2
Parks, B, “Testing shows elevated lead levels in some Portland drinking water” OPB, November 30, 2021 accessed December 1, 2021 https://www.opb.org/article/2021/11/30/lead-portland-oregon-drinking-water/
Wani AL, Ara A, Usmani JA. Lead toxicity: a review. Interdiscip Toxicol. 2015;8(2):55-64. doi:10.1515/intox-2015-0009