Calcium Absorption

Confused About Calcium?

Individual Calcium Needs

When it comes to calcium, many people believe if a little bit is good, more must be better. But, what if it is really an issue of absorption and preventing calcium loss, rather than consuming more and more calcium? Actually, much research is finding exactly that – age-related bone loss may be more attributable to reduced absorption and excessive calcium loss than to inadequate calcium intake.[1] Some health professionals believe we need only 500 mg of calcium per day for proper body and bone health. Nancy Appleton, Ph.D., author of Healthy Bones: What You Should Know About Osteoporosis, believes this to be enough calcium IF the body is in homeostasis (balance). She goes on to explain that if the body is not in homeostasis, even the 1,000 mg to 1,200 mg governmental calcium recommendation will not be properly utilized and absorbed.[2],[3]

Consider the factors presented below that impede proper calcium absorption, influence its excretion, and impact overall body homeostasis. Next, look for bodily signs of calcium deficiency, such as joint pain, nervousness or irritability, twitching muscles, loose teeth, tendency to form cavities, brittle nails, spastic stomach, muscular tension, soft teeth, and vertically ridged nails.[4] After deciding on the amount of calcium that is right for you, estimate the amount being consumed through food and then supplement with the difference to bring it up to the desired amount.[5] Keep in mind, taking in over 2000 mg per day can upset your body chemistry, interfere with zinc absorption, deposit calcium in soft tissues, and promote arthritis and arteriosclerosis.[6]

Absorption Factors and Homeostasis

  • Gastrointestinal health and Stomach Acid: The integrity of one’s intestines has profound effects upon the absorption of nutrients.[7] Adequate stomach acid levels are necessary for many forms of minerals to be properly broken down and absorbed.[8],[9],[10],[11]
  • Exercise: Physical activity can actually improve bone uptake of calcium and other minerals.[12] However, excessive physical activity can have the opposite effect.[13]  Remember, balance is the key.
  • Stress: Mental or physical stress can result in the loss of calcium and other nutrients from the body. For example, the stress hormone cortisol mobilizes calcium from bones and increases its excretion through the urine.[14] A net loss of as much as 900 mg of calcium can occur each day during times of worry and tension.[15]
  • Dietary Factors: Calcium absorption requires the presence of healthy dietary fats, such as those found in olive oil, fish oils, coconut oil, and butter. These fats have been shown to actually preserve bone; however, damaged fats, found in fried foods, partially hydrogenated fats, and poorly processed oils, have the opposite effect.[16],[17] Urinary excretion of calcium and magnesium increases after sugar [18],[19]  Caffeine and alcohol literally drain your body of calcium due to their diuretic effect.[20],[21] An excess of salt can result in urinary calcium loss.[22],[23],[24] Adequate protein is also a critical factor in bone health; it makes up collagen and reinforces bone. Calcium and protein appear to work together to preserve bone health.[25]
  • Prescription drugs: Many drugs can interfere with the storage of calcium. For example, corticosteroids and[26] antibiotics increase calcium excretion.[27]
  • Heavy metal toxicity: These substances can draw calcium out of bones as a buffering agent. Some examples include cadmium found in cigarette smoke[28] and aluminum found in anti-acids, processed cheese, deodorant, and pots and pans.[29]
  • Calcium’s Nutrient Partners: Many nutrients work synergistically to support bone. Without its nutrient partners, calcium is not able to be properly incorporated into the bone matrix and may actually lead to hardening of soft tissues, such as the arteries and kidneys. Vitamin D is not only required for calcium absorption, but it also plays a critical role in regulating calcium metabolism and ensuring that once calcium is delivered to the bone, it stays there.[30] Vitamin K, and especially the K2 form, is necessary for delivering calcium to the bones and then for keeping it there. Magnesium is part of the bone matrix and is also necessary for the absorption of calcium. Boron is involved in calcium metabolism and also activates certain important bone-building hormones.[31] Simply put, a well-rounded balance of nutrients is essential for calcium utilization and absorption.
  • Amount Consumed: The body can absorb only so much elemental calcium at one time. Generally speaking 500 mg is the maximum amount that can be absorbed at one time.[32] It is important to divide your calcium intake (both from supplements and from foods) throughout the day to optimize absorption.

The bottom line is that there are numerous factors that play into calcium absorption, utilization, and excretion; optimal calcium status is not achieved merely by consuming as much of this mineral as possible.

Calcium Supplementation

Taking a regular calcium supplement to fill in the holes from your diet will help insure that you get adequate calcium each day. Supplementation of this mineral is particularly important for those with low appetites, poor dietary habits, low tolerance for calcium-rich foods, inadequate digestive health, as well as those on medications and who have an increased risk of bone loss.[33]

What is Elemental Calcium? The term elemental calcium refers to calcium in its most elemental state. In food and supplements, calcium usually comes to us bound to another compound that acts as a transporter (such as citrate or carbonate). In order for the calcium to be absorbed in the small intestine the transporter must first be “cleaved” from the calcium. This usually happens with the help of hydrochloric acid (stomach acid) in the stomach. When choosing a supplement it is important to know the amount of “elemental” calcium each pill contains, not just the weight of the pill, which would also include the weight of the carrier. The Supplemental Facts Panel should provide this information. Depending on the form, elemental calcium can range from 9-50% of the complex. This is why it is necessary to take more than one pill to get the Recommended Daily Allowance and also one reason why you may have to take more of one form versus another to get the same amount.

Besides whole food and bone-building supplements, there are herbal tea recipes that can be incorporated to boost calcium and bone nutrient intake. For example, the herbalist Susan Weed in her book New Menopausal Ways, The Wise Woman Way recommends one ounce nettles, one tablespoon horsetail (shave grass), and one tablespoon sage. To make this nourishing herbal infusion, crush the sage between palms and drop into a quart container with the other two herbs. Pour one quart boiling water over the herbs, covering it tightly, and letting it brew for four hours or more (overnight will work).[34],[35] In the morning, strain out the mineral-rich liquid and drink it over ice or heated, or any other way you enjoy it. Each cup of this infusion not only contains approximately as much calcium as a cup of milk, but also many of the other partners to this important bone mineral.

How do you decide what calcium supplement is best for you? Ask these questions:

  • Considering the information presented, what feels right to me?
  • How is my digestive system functioning?
  • How many pills do I want to take?
  • What form will I take regularly – tablet, chewable, liquid, powder?
  • Where am I getting the nutrient partners for calcium?
  • Do I need to include these extra nutrients in my calcium supplement?

The chart on the next page will help you to further determine which calcium supplement is right for you.

Form What You Need to Know
InorganicCalcium CarbonateCalcium Phosphate

Calcium Oxide

These forms tend to be more compact so fewer pills are necessary to achieve desired amounts, however their absorption is more strongly dependent on the presence of stomach acid. This form may not be well absorbed by those taking acid-reducing medication or those with low-stomach acid (hypochlorhydria). In general absorption is enhanced when taken with a meal.
Amino Acid Chelate[36]Calcium AspartateCalcium Lysinate

Calcium Glycinate

Calcium Histidinate

Calcium is easily freed in this form and absorption is generally high, regardless of stomach acid. Plus, the body is able to use the amino acid that was previously bound to the calcium for other bodily functions. Calcium contributes a smaller fraction of the weight of an amino acid chelate than of other supplemental forms, so more pills are necessary to achieve desired amounts.
Organic[37]Calcium CitrateCalcium Gluconate

Calcium Lactate

These forms of calcium are often recommended because in general they are absorbed better than the inorganic forms (such as carbonate) regardless of stomach acid output, and are not as bulky as the amino acid chelates.
Microcrystalline Calcium Hydroxyapatite (MCHC) MCHC is the form in which calcium is stored in our bones. In addition to calcium, supplemental MCHC also contains phosphorus, collagen and bone-specific growth peptides. There are limited studies on supplemental MCHC, although some have shown it to be more effective at slowing bone loss than other forms such as calcium carbonate.[38]  Supplemental MCHC is bovine sourced.
Calcium Citrate Malate (CCM)[39],[40] A mixture of calcium, citric acid and malic acid make up this form of calcium. Regardless of stomach acid output, it is slightly better absorbed than other forms of calcium, particularly calcium carbonate. It tends to be more expensive and is bulky, so more pills will be needed to achieve a desired dose.
Algae Derived These products rely on a mineral rich sea plant to supply a whole-food plant source of calcium. Along with calcium, these sea plants also contain magnesium and at least 70 other trace minerals. In a small number of both animal and human studies, use of algae-based calcium showed improvements in bone mineral density.[41],[42],[43] It should be noted that in the human studies, bone co-factors such as vitamin D, vitamin K and strontium were usually added. Further research is needed to evaluate absorption of these forms of calcium.
Coral Calcium/Bone Meal/Oyster Shell These forms are natural sources of calcium carbonate and as such have similar absorption issues. In the past there was concern about contaminants such as lead in these forms, but today’s Good Manufacturing Practices (GMP) require manufacturers to test for such contaminants. In the case of coral calcium some concern has been raised about the environmental impact of harvesting from the world’s coral reefs.

References

[1] Nordin BEC, Polley KJ, Need AG, Morris HA, Marshall D. The problem of calcium requirement. Am J Clin Nutr 1987;45:1295–304

[2] Appleton, Nancy, Ph.D. Healthy Bones What you Should Know About Osteoporosis. Avery Publishing Group, Inc.Garden City Park, NY. 1991.

[3] Spiller, Gene Ph.D., Bruce, Bonnie, DPH, R.D. Calcium Nature’s Versatile Mineral. Avery. New York. 2000.

[4] Igram, Cass, Dr. Self Test Nutrition Guide. Knowledge House. Buffalo Grove, Ill. 1994.

[5] Appleton, Jeremy. N.D. Calcium Supplements for Bone Strength. Healthnotes Newswier. 9/01. Found at http://www.healthwell.com/news/index.cfm?news=1038.

[6] Appleton, Nancy, Ph.D. Healthy Bones What you Should Know About Osteoporosis. Avery Publishing Group, Inc.Garden City Park, NY. 1991.

[7] Whiting, Steven, PhD. Osteoporosis: A Factor of Aging. Found at www.healingwithnutrition.com on Jan 9th 2001.

[8] Ivanovich P, Fellows H, Rich C. The absorption of calcium carbonate. Ann Intern Med 1967;9:271–85.

[9] Bo-Linn GW, Davis GR, Buddrus DH, et al. An evaluation of the importance of gastric acid secretion in the absorption of dietary calcium. J Clin Invest 1984;73:640–7.

[10] Serfaty-Lacrosniere C, Woods RJ, Voytko D, et al. Hypochlorhydria from short-term omeprazole treatment does not inhibit intestinal absorption of calcium, phosphorus, magnesium or zinc from food in humans. J Am Coll Nutr 1995;14:364–8.

[11] Heaney RP, Smith KT, Recker RR, Hinders SM. Meal effects on calcium absorption. Am J Clin Nutr 1989;49:372–76.

[12] Hass, Elson, MD. Staying Healthy with Nutrition. Celestial Arts, Berkeley, CA. 1992.

[13] American Journal of Clinical Nutrition. August 2000; 72: 466-471.

[14] Brown SE. Better Bones, Better Bodies. New Canaan, CT: Keats Publishing; 1996.

[15] Garrison, Robert, M.A., R. Ph. and Elizabeth Somer, M.D., R.D. The Nutrition Desk Reference. Second Edition. Keats Publishing, Inc. New Canaan, Connecticut. 1990.

[16] BA Watkins et al, “Importance of Vitamin E in Bone Formation and in Chondrocyte Function” Purdue University, W. Lafayette, IN 47907

[17] Germano, Carl, RD, CNS, LDN. The Osteoporosis Solution. Kensington Books. 1999.

[18] Murray, Michael, N.D. Encyclopedia of Nutritional Supplements. Prima Publishing, Rocklin, CA. 1996.

[19] Germano, Carl, RD, CNS, LDN. The Osteoporosis Solution. Kensington Books. 1999.

[20] Appleton, Nancy, Ph.D. Healthy Bones What you Should Know About Osteoporosis. Avery Publishing Group, Inc.Garden City Park, NY. 1991.

[21] Germano, Carl, RD, CNS, LDN. The Osteoporosis Solution. Kensington Books. 1999.

[22] Evans CEL, Chughtai AY, Blumsohn A, et at. The Effect of Dietary Sodium on Calcium Metabolism in premenopausal and postmenopausal women. Eur J Clin Nutr 1997; 51:394-99.

[23]Zarkadas M, Geougeon-Reyburn R, Marliss EB, et al. Sodium chloride supplementation and urinary calcium excretion in postmenopausal women. Am J Clin Nutr 1989;50:1088–94.

[24] Spiller, Gene Ph.D., Bruce, Bonnie, DPH, R.D. Calcium Nature’s Versatile Mineral. Avery. New York. 2000.

[25] Calcium intake influences the association of protein intake with rates of bone loss in elderly men and women. Dawson-Hughes, B., Harris, S. S., American Journal of Clinical Nutrition 2002 Apr;75(4):773-779.

[26] Igram, Cass, DR. Self-test Nutrition Guide. Hiawatha, Iowa. 1994.

[27] Appleton, Nancy, Ph.D. Healthy Bones What you Should Know About Osteoporosis. Avery Publishing Group, Inc.Garden City Park, NY. 1991.

[28] Kessler, George, D.O, P.C., The Bone Density Diet. Ballantine Books. 2000.

[29] Appleton, Nancy, Ph.D. Healthy Bones What you Should Know About Osteoporosis. Avery Publishing Group, Inc.Garden City Park, NY. 1991.

[30] Nutrition and Bone Health. Natural Grocers Coaching Document. August 2012.

[31] Nutrition and Bone Health. Natural Grocers Coaching Document. August 2012.

[32] Calcium quick facts. Office of Dietary Supplements. http://ods.od.nih.gov/pdf/factsheets/Calcium-QuickFacts.pdf. Accessed June 17, 2013.

[33] Spiller, Gene Ph.D., Bruce, Bonnie, DPH, R.D. Calcium Nature’s Versatile Mineral. Avery. New York. 2000.

[34] Lieberman, Shari, PhD. The Real Vitamin and Mineral Book. Avery Publishing Group. New York. 1997

[35] Ley, Beth. Ph.D. Calcium: The Facts. BL Publications. Detroit Lakes, MN. 2001.

[36] Heaney RP, Recker RR, Weaver CM. Absorbability of calcium sources: the limited role of solubility. Calcif Tissue Int 1990;46:300–4.

[37] Murray M. Encyclopedia of Nutritional Supplements. Rocklin, CA: Prima Publishing; 1996.

[38] Straub DA. Calcium supplementation in clinical practice: A review of forms, doses and indications. Nutr Clin Pract. 2007;22:286-296.

[39] Miller J, Smith D, Flora L, et al. Calcium absorption from calcium carbonate and a new form of calcium (CCM) in healthy male and female adolescents. Am J Clin Nutr 1988;48:1291–4.

[40] Smith KT, Heaney RP, Flora L, Hinders SM. “Calcium Absorption from a New Calcium Delivery System (CCM). Calcif Tissue Int. 1987;41:351-52.

[41] Kaats GR, Preuss HG, Croft HA, Keith SC, Keith PL. A comparative effectiveness study of bone density changes in women over 40 following three bone health plans contains variations of the same novel plant-sourced calcium. Int J Med Sci. 2011; 8(3):180-191.

[42] Michalek JE, Preuss HG, Crotf HA, Keith PL, Keith SC, Dapilmoto M, et al. Changes in total body bone mineral density following a common bone health plan with two versions of a unique bone health supplement: a comparative effectiveness research study. Nutr J. 22011; 10(32). doi: 10.1186/1475-2891-10-32.

[43] Aslam MN, Kreider JM, Paruchuri T, Bhagavathula N, DaSilva M, Zernicke RF, et al. A mineral-rich extract from the red marine algae Lithothamnion calcareum preserves bone structure and function in female mice on a Western-Style diet. Calcif Tissue Int. 2010; 86(4):313-324.