Nutrient Spotlight: Calcium
Calcium is the most abundant mineral in the human body. Contrary to popular belief, calcium is used in many ways beyond bone health. This mineral plays a key role in helping with muscle contraction, nerve function, transporting messages within our body, helping with blood transport, maintaining body pH, and releasing enzymes and hormones (10). While a majority of your calcium is located in your teeth and bones (around 99%), the other 1% is found in your blood, extracellular fluids, and cell tissues (10).
Best Sources
We promote a ‘food-first’ approach in The 131 Method, which means we prefer calcium come from food and not supplements. In fact, supplementation is quite controversial. Though it’s become quite routine in older populations (especially women), you may want to pause before jumping on that bandwagon. Recent scientific evidence suggests calcium supplementation can result in an increased heart disease and heart risk (1-6). Researchers believe the burst of calcium intake above a normal dietary intake is not absorbed by bones and may facilitate calcification in the arteries and kidneys (leading to kidney stones) (7-8). On the other hand, some evidence indicates supplements are effective (9). To add to the confusion, calcium intake and absorption are two different things. What we consume in milligrams does not necessarily translate to the amount the body uses. We’ll discuss this more below.
We must remember food and supplements are not equal. Taking an isolated nutrient is not the same thing as eating whole foods that contain many nutrients. An example of the synergistic work of nutrients is vitamin K2 and calcium. Vitamin K2 optimizes calcium’s use in the body. It ensures it goes to the right place (bones) versus arteries and kidneys. Two other nutrients that work with calcium include Magnesium and Vitamin D.
Tricky Tricky
As you can see, calcium supplementation is tricky; there’s conflicting evidence on the various forms and proper dosing. Why? For one, we’re all individuals with different gut functions, DNA, and metabolic rates. We may absorb and use calcium at different rates. This makes it hard to catch data in a 1000+ person study. You simply can’t control for all of those factors.
The take-home message is that science is not clear on whether calcium supplements are helpful or dangerous. The smart move is to focus on dietary calcium intake and avoid supplementation until further research is done. You can also work with a provider who specializes in nutrition specific to your needs. Once again, food first! It’s nearly impossible to consume too much calcium from food sources.
Can I get calcium without dairy?
Dairy is a common inflammatory food and many people feel better without it. This is due to the casein (protein) or the lactose (sugar). However, if dairy is eliminated, so too are the other nutrients that come with it, like calcium. Rest assured, there are plenty of ways to get adequate calcium without dairy. The government’s Recommended Dietary Allowances (RDA) for calcium intake is listed below. But some experts believe we need far less to maintain healthy bones. Most non-dairy milks contain MORE calcium than cow’s milk.
How much do I need per day?
The amount of calcium you need daily is generally based upon your age and gender. See the chart below for the RDAs (10). Absorption increases during pregnancy, breast feeding, growth spurts, and with certain types of exercise (11-12).
| Life Stage | Recommended Dietary Allowance |
| Males | |
| 19-50 years of age | 1000 mg |
| 51-70 years of age | 1000 mg |
| >70 years of age | 1200 mg |
| Females | |
| 19-50 years of age | 1000 mg |
| 51-70 years of age | 1200 mg |
| >70 years of age | 1200 mg |
| Pregnancy | |
| 19-50 years of age | 1000 mg |
| Lactation | |
| 19-50 years of age | 1000 mg |
In addition to the amount of calcium in food, you want to consider the absorption rate. Foods like collard greens and kale have a high absorption rate (65% and 49%, respectively.) However, milk and most dairy products only have a 32% absorption rate. To simplify this, let’s compare 1 cup of collard greens with 1 cup of milk (12-15).
- 1 cup of milk = about 300 mg
- 1 cup of collard greens = 266 mg
- Absorption rate of milk = 32%
- Absorption rate of collard greens = 65%
- Calcium absorbed from 1 cup of milk = 96 mg
- Calcium absorbed from 1 cup of collard greens = 173 mg
See why dairy removal isn’t a concern as long as you consume a diet rich in plant sources?! In fact, plants trump milk when it comes to the amount of calcium absorbed.
Below are some great calcium-containing foods (listed in general order of highest to lowest absorption rates) (12, 16).
- Collard greens
- Broccoli
- Bok choy
- Turnip greens
- Kale
- Mustard greens
- Yogurt
- Kefir
- Cheese
- Milk
- Sardines (with bones)
- Salmon (with bones)
- Spinach
- Swiss chard*
- Dried seaweed*
- Chinese cabbage*
- Watercress*
- Okra*
- Almonds*
- Bone broth*
- Sesame seeds*
- Tahini* (ground sesame seeds)
*absorption rate unknown
Factors that slow calcium absorption
There are many factors that can affect calcium absorption(10-11).
- Spinach, rhubarb, chard, and beet greens contain oxalic acid, which interfere with absorption
- Phytic acid found in cereal grain husks prohibit calcium absorption
- Dietary fiber can also interfere with absorption, but this is with very high fiber diets of >30 grams of fiber/day
- Fat malabsorption lowers absorption
- Calcium absorption declines with age
- Inadequate vitamin D can also decrease absorption in the body
Whoa, we covered a lot there! Our hope was to shed some light on a topic that is tough to understand. Mostly because it’s not fully understood in research yet. The best thing you can do for yourself, for your growing kids and your aging parents, is to eat real food. Load up on those green, veggies, and be cautious of supplements.
Resources:
- https://www.ncbi.nlm.nih.gov/pubmed/23381719
- https://www.ncbi.nlm.nih.gov/pubmed/15514282
- https://www.ncbi.nlm.nih.gov/pubmed/22626900
- https://academic.oup.com/jcem/article/97/12/4531/2536513
- http://www.bmj.com/content/341/bmj.c3691
- http://heart.bmj.com/content/98/12/920.full
- http://heart.bmj.com/content/98/12/895?sid=d8a426b8-b2d6-4119-91ac-b3eaa2e7c337
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566462/
- https://www.ncbi.nlm.nih.gov/pubmed/17720017
- Mahan, L. Kathleen, and Sylvia Escott-Stump. Krause’s Food & Nutrition Therapy. 12th ed., Saunders Elsevier, 2008.
- “Calcium.” NIH Office of Dietary Supplements, U.S. Department of Health and Human Services, 17 Nov. 2016, ods.od.nih.gov/factsheets/Calcium-Consumer/.
- https://www.sciencedirect.com/science/article/pii/S0889157506001062
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3448090/
- https://www.ncbi.nlm.nih.gov/pubmed/21310303
- https://academic.oup.com/jn/article/113/2/388/4755200
- https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/
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