Calcium: Different opinions/who is right. And a way to tell if you if you getting enough.
Should you use supplements? Here is the best way to monitor your calcium intake.
This post on calcium is a lineup to tomorrow’s post on bone health and the DEXA scan. I saw that the Unbecoming substack was posted today on bone health and the scan, but I will continue with my post tomorrow. I scanned his post and will not have time to read it until later, but it appears the two posts will complement each other nicely and fill in the gaps of the other post.
Upcoming Posts: I have been asked about the new niacin study. On Monday, I will send out a post you need to read to understand my comments on the Niacin study, which I should have done by Tuesday.
In this post about studies that have stated supplements increase mortality, I mentioned conflicting information about calcium, but the studies did not distinguish whether the calcium was sourced from food or supplements, and the studies used surveys, which can be very unreliable.
A reader in the comment section of a recent post shared a link to Ray Peat on his thoughts on calcium.
Ray Peat’s Calcium Views
Peat believes a calcium deficiency leads to many health issues and that we should consume dairy to meet our calcium needs. But Peat did not state if he meant we should consume dairy at the RDA recommendations daily from food sources or if he meant the RDA amounts are inadequate and we need more. (The RDA amounts for calcium will vary slightly based on age but range from 1000 to 1200 mg for adults).
Based on his article, I was unclear on how much calcium we should consume.
He is a promoter of calcium sourced from dairy.
But there are some issues with dairy
Many people have dairy sensitivity or are lactose intolerant.
Many people do not have access to/or cannot afford raw dairy or grass-fed dairy.
Others argue that we should not consume dairy once we are past infancy.
Some people love dairy so much that they consume it excessively, leading to weight gain and crowding out other nutrient-dense foods.
Dr. Levy’s Calcium Views
Dr. Levy believes we should not supplement with calcium, and atherosclerosis and osteoporosis are caused by high calcium intake.
Levy states that calcium sourced from dairy is just as dangerous as calcium sourced from supplements.
He also does not like raw milk and states we should consume only minimal amounts of dairy.
The Weston Price Foundation states that raw dairy contains built-in protective immunologic systems, enzymes, hormones, mucins, fibronectin, beneficial bacteria, and other healthful substances all in one package.
However, in Levy’s book, he does not cite research indicating that we should not consume milk as a calcium source due to health hazards.
Levy is correct that calcium can relocate to other organs and tissues instead of staying in the bones where it belongs.
Chris Kresser’s Calcium Views
According to Chris Kresser, 44% of the population in the US does not get enough calcium. One of the reasons is due to the bioavailability of calcium from certain foods.
For example, only 5% of calcium from spinach is absorbed. Of the 115 mg of calcium present in a serving of spinach, only 6 mg is absorbed. You’d have to consume 16 cups of spinach to get the same amount of bioavailable calcium in one glass of milk!
Phytates are anti-nutrients found in large amounts in grains and legumes and bind to calcium, iron, and zinc, making them unavailable for absorption.
Proton pump inhibitors (PPIs), prescribed for acid reflux, increase the risk of vitamin and mineral deficiencies—including vitamin B12, C, calcium, iron, and magnesium.
In the video below, Chris Kresser discusses how calcium in supplements can be harmful and increase mortality risk, while calcium from food can be helpful.
Consuming calcium in a supplement affects the body differently than if it came from food. The calcium in a supplement can stay in the arteries and organs rather than go to the bones and teeth, which is associated with increased CVD risk.
Side Note on C. Kresser: I have not followed him since 2020 since this was another person in the health space that I was disappointed by when he completely ignored the cov!d topic and what people can do to support their health. I may be incorrect since I no longer follow him. Like others, he does share some reputable information in the health space.
Kresser, Levy, and Peat agree that calcium is best sourced from food. Even though dairy is the best absorbable calcium source, Levy does not think we should consume dairy.
Kresser and Peat think our intake is too low, and Levy believes it is too high. Based on what I read, I think Kresser thinks we are not meeting the RDA calcium requirements, Peat thinks the RDA is too low, and Levy thinks the RDA is too high, but none specifically stated this, so I may be misinterpreting them.
The Problem with Calcium Absorption and Foods that Contain Oxalates
Oxalates found in plant foods can impact the absorption of the plant's minerals because oxalic acid will bind to calcium in the digestive tract, block its absorption, and increase fecal calcium excretion (Gropper & Smith, 2018).
If an individual consumes a meal high in oxalates, the calcium absorbed is less than 5%. Additionally, unabsorbed oxalates can chelate to magnesium and iron, reducing their bioavailability (Gropper & Smith, 2018).
Plants high in oxalates include spinach, rhubarb, Swiss chard, beets, celery, eggplant, okra, squash, strawberries, blackberries, pecans, peanuts, tea, cocoa, and other whole foods.
Calcium-containing leafy greens that are safe to eat if one is trying to avoid foods high in oxalates include kale, broccoli, mustard greens, turnip greens, and collard greens (Low Oxalate Information, 2012).
Other Factors That Influence Calcium Absorption
What you need for calcium absorption: Protein consumption and some fat. You also need cofactors such as magnesium, boron, silicon, and vitamins D, K, A, and C.
What inhibits Calcium Absorption
Excess phosphorus, magnesium, and zinc
Excess tannins (coffee, tea, nuts some vegetables)
Antacids and proton pump inhibitors (shuts down stomach acid)
Oxalates
Phytates
What Depletes Calcium Absorption
You may be getting enough calcium in your diet, but you may be depleting it by other factors in your diet and lifestyle.
Soda (the high phosphorus content)
Vitamin D deficiency (more on this below)
Excess caffeine
Alcohol
Nicotine
Sugar
Stress
Certain medications
More on the Vitamin D and Calcium Connection
Adequate Vitamin D is needed to help regulate intestinal absorption of calcium from our foods. If you are vitamin D deficient, your calcium absorption will be impaired. Once your vitamin D level is raised to adequate levels and you have absorbed as much calcium to meet your body’s needs, increasing vitamin D intake will not affect calcium absorption because you have reached your plateau.
So vitamin D helps you meet your calcium needs, but vitamin D intake has no effect if you have enough calcium.
As you can see, a system is in place to help regulate the amount of calcium absorbed and utilized from food and prevent excess calcium in the body.
Hence, we can see why it is best to know our vitamin D levels and get calcium from food, not supplements.
How Much Calcium Can You Absorp at One Meal?
Calcium is absorbed via active transport and diffusion (Gropper & Smith, 2018). If the meal contains 400-500 mg of calcium, the active transport system accounts for 50-60% of the total amount of calcium consumed and absorbed via the small intestines (Gropper & Smith, 2018). In diffusion, a passive process, it is estimated that 8-23% of calcium is absorbed; thus, it is not the major calcium absorption pathway (McCormick, 2002).
Generally, it is recommended not to consume more than 400-500 mg of calcium at one time, as more than that will not be utilized.
Depending on the calcium form used in a supplement, absorption can range from 27-39% (Gropper & Smith, 2018).
This is probably why most calcium-containing bone supplements require you to take the tablets three times daily, and each dose equals 500 mg of calcium.
Calcium supplement absorption can be impacted by whether the supplement was taken during a fasted state or with a meal. The absorption rate of calcium supplements increases if taken with food (Gropper & Smith, 2018).
Vegans, Vegetarians, and Higher Fracture Rates
O'Keefe et al. (2016) recommend animal protein sources to support bone density because some plant calcium sources contain oxalates and phytic acid, inhibiting calcium absorption. O'Keefe et al. (2016) base this on studies that showed vegans have higher fracture rates due to low calcium intake and poor absorption of plant-based calcium.
They continue that while high amounts of milk consumption have been shown to increase fracture risk, cheese and fermented dairy products such as yogurt and kefir decreased rates of hip fractures.
However, this study was observational, and firm conclusions should not be drawn from this.
O’Keefe et al. (2016) encouraged sourcing calcium from bones by drinking bone broth or adding bone meal to the diet in supplement form.
Why You Should Avoid Taking a Calcium Supplement
Calcium supplements may be unabsorbable and contain heavy metals such as lead. Some people do not realize they consume over the RDA amounts because their multivitamin/mineral and bone supplements contain calcium and calcium from their diet.
Food Sources of Calcium
Remember that the total milligram amount absorbed will be less from some foods, such as spinach, versus from yogurt.
Dairy Sources of Calcium Include
Yogurt (plain whole milk 6 ounces) 206 mg.
Cow’s milk (whole, grass-fed, 4 ounces) 138 mg.
Parmesan cheese (1 ounce) 331 mg.
Whey protein powder 1 scoop (1 ounce) 200 mg.
Non-Dairy Sources of Calcium
Sardines (whole with bone, canned, 3.5 ounces) 382 mg. (My favorite is Wild Planet Brand)
Sesame seeds (think tahini butter, hummus) 2 T. 176 mg.
Collard Greens Cooked, ½ c. 134 mg.
Spinach cooked, ½ c. 123 mg.
Almonds 1 ounce 76 mg.
Figs, dried, 5 figs 70 mg.
White Beans 1 c. (from can) 191 mg.
Canned Salmon ½ can with bones in 232 mg.
Bok Choy 1 c. 74 mg.
Kale (2 c. raw chopped) 188 mg.
Black eyes peas (canned) ½ c. 185 mg.
Oranges (1 medium) 65 mg.
Turnip Greens (1 c. chopped and cooked) 197 mg.
Firm Tofu ½ c. 861 mg.
Poppy Seeds 1 T. 126 mg.
Amaranth grain 1 c. cooked 116 mg.
Broccoli 2 stalks cooked 250 mg.
Sunflower seeds 3 ½ ounce 110 mg.
Green beans 3 ½ ounce 56 mg.
Walnuts 3 ½ ounce 90 mg.
Tip: Soak almonds, walnuts, and sunflower seeds in filtered water, drain, and put them into the dehydrator to remove phytates. Doing so will increase the calcium absorption from these foods.
How Much Calcium Do You Really Need?
(this is based on the RDA in the U.S)
Ages 1-3 500 mg.
Ages 4-8 800 mg
Ages 9-13 1300 mg
Ages 19-50 1000 mg.
Ages over 50 1200 mg.
Pregnant 1200 mg
Lactating 1200 mg.
Testing, What to Look at on Labs, and What Test to Ask For
A total calcium test is the most common one you will see on your basic metabolic panel, and this test can only look at the calcium in your blood. Too much or too little can indicate bone disease, thyroid disease, parathyroid disorders, kidney disease, and other conditions.
A total calcium test measures the total amount of bound and free calcium in the blood. Bound calcium is attached to proteins in your blood. Only 1% of your total calcium is in your blood. The rest is in your bones and teeth.
If your total calcium test result is low, the low calcium would be secondary to changes in albumin concentration and pH. Fifty percent of calcium is bound to albumin; therefore, it makes sense that when calcium is low, albumin is low, too (Gropper & Smith, 2018; Litchford, 2017).
Therefore, when you have your lab test results, look at the albumin and calcium levels. If albumin is low, this can occur in response to chronic or acute inflammation.
The ionized calcium test measures only “free calcium” in your blood that is not attached to proteins.
The ionized calcium test would be a better choice since it is not affected by changes in serum albumin. This test is more sensitive and reliable in determining an accurate measure of total calcium, but most doctors will not run this test unless you ask (Litchford, 2017).
Bottom Line:
Avoiding calcium supplementation and focusing on calcium from dietary sources may be best. Do not rely on dairy only as your calcium source. Include a variety of sources so that you combine calcium with other needed nutrients. Identify the factors in your life (such as excess alcohol or proton pump inhibitors) that may prevent you from utilizing the calcium you consume. Don't consume large amounts of calcium at one time; take in smaller amounts at each meal. Mix in plant-based and non-vegan calcium sources, including salmon and sardines.
Know your vitamin D levels. www.Omegaquant.com has blood spot vitamin D tests you can do at home. I suggest doing one at least once per year, and if your level is low, test every 6 months.
If you want to know your bone/calcium status, a DEXA scan, the ionized calcium test, or the Spectra Cell micronutrient test may be the best options.
I will write more on the DEXA scan and osteoporosis in another substack.
Show my posts some love, please! It is just me writing, reading, researching, and seeing clients!
I do not use mainstream social media, so please share my posts so that more people can get informed on how to get and stay healthy.
This is NOT information allopathic practitioners will share with you.
Paid subscribers get supplement discounts at my Fullscript online apothecary (if they reside in the US) and consult discounts.
Gropper, S., & Smith, J. (2018). Chapter 11. Major Minerals. In Advanced nutrition and human metabolism (7th ed.). Cengage Learning.
Haas, E. & Levin, B. (2006) Staying healthy with nutrition. The complete guide to diet and nutritional medicine. Celestial Arts.
Murray, M., Pizzorno, J. & Pizzorno, L. (2005) The encyclopedia of healing foods. Atria Books
Litchford, M. (2017). Laboratory assessment of nutritional status: Bridging theory and practice. Case Software.
Low Oxalate Information. (2012, June 7). Guide to low oxalate greens. http://lowoxalteinfo.com/guide-to-low-oxalate-greens/
McCormick, C.C. (2002). Passive diffusion does not play a major role in the absorption of dietary calcium in normal adults. The Journal of Nutrition, (132)11 https://doi.org/10.1093/jn/132.11.3428
O’Keefe, J.H., Bergman, N., Carrera-Bastos, P., Fontes-Villalba, M., DiNicolantonio, J.J., & Cordain, L. (2016). Nutritional strategies for skeletal and cardiovascular health: Hard bones, soft arteries, rather than vice versa. Open Heart, 3, e000325. https://doi.org/10.1136/openhrt-2015-000325
Wood, R. (2010) The new whole foods encyclopedia. Penguin Books
Great summary! Thank you. I think your Bottom Line recommendations are right on target for most people.
A young orthopedic surgeon told me to just up my vitamin d and most likely would never be low on calcium. That was over 6+ years ago and sure enough it's been true. However, prior every year before I was low on Vitamin D and calcium! Now neither is an issue and I usually eat ONCE a day!