Calcium is an important issue in women’s health. This vital mineral has been linked to low bone density and osteoporosis in women as they age due to declining hormone levels. Low bone density can increase the risk of fracture, disability and mortality in senior women. The truth is, calcium is important throughout life and is readily available in abundant numbers through food. This article will help you understand why calcium is important, where to find calcium in food, and how to supplement calcium if needed.
Calcium is one of the most abundant minerals in the body. The majority of calcium is found in the bones and teeth while the rest is found in other tissues and in general circulation. Calcium metabolism is dependent on other nutrients and hormones for absorption including Vitamin D, parathyroid hormone and calcitonin. When it comes to bone health, calcium works in combination with other important nutrients including the fat soluble vitamins, phosphorous, magnesium, silicon, strontium, and boron to lay bone matrix. But there is so much more to calcium than bone health!
Calcium plays the following essential roles in the body:
Formation of the structure of bones and teeth
Muscle contraction
Nerve signaling
Blood vessel contraction and expansion
Perhaps most importantly, calcium works in combination with magnesium, sodium and potassium to regulate the blood, nerves, muscles - particularly the heart muscle.
From a survival perspective, regulation of the heart muscle is much more important than bone formation and so it takes physiological priority. Meaning that if the body detects low blood calcium the body will stimulate the release of calcium from the bones. This is why, in calcium deficient diets, such as the Standard North American Diet, osteoporosis is such as problem. The body is busy protecting the heart by taking from the bones.
In addition, numerous early studies showed that calcium intake was positively related to a reduced risk of hip fracture and a reduced risk of heart disease. For example, individuals with higher calcium consumption had lower blood pressure and cholesterol. Based upon this research and the incidence of osteoporosis it became standard practice to recommend calcium supplementation, particularly in post menopausal women who were prone to lower bone density due to dropping estrogen. Typical dosages of calcium supplements recommended to women were in the 1000-1200mg range per day.
Recommended Daily Allowances acknowledge that calcium absorption changes as we age:
Infants 0-6months: 200mg
Children 7-12 months: 260mg
Children 1-3 years: 700mg
Children 4-8 years: 1000mg
Children 9-18 years: 1300mg
Men and women 19 - 50 years: 1000mg per day; upper limit 2500mg
Women 51 - 70 years: 1200mg per day; upper limit 2000mg
Men 50 and 70 years: 1000mg per day; upper limit 2000mg
Men over 71 years: 1200mg per day; upper limit 2000mg
Pregnancy & Breastfeeding: Although the general recommendation remains at 1000mg per day women should aim for an additional 200-400mg to make up for increased demand.
Individuals who are consuming calcium from foods high in oxalic acid (ex. spinach, chard, kale, beets) and phytic acid (whole grains, seeds, nuts, beans) should aim for an additional 200-400mg per day to make up for more limited bioavailability of calcium.
More recent studies including the Women’s Health Initiative found that women with an elevated intake of calcium (greater than 1000mg), particularly those individuals taking calcium supplements were at greater risk of cardiovascular events by 15-22%. They demonstrated elevated lipid levels related to blood clotting and increased calcium deposits in the arteries. In addition, high supplemental doses of calcium was associated with increased risk of kidney stones.
Science has interpreted these more recent findings with a theory that higher dose supplemental calcium, greater than 500mg per sitting, is not well broken down by the body. It is too large a quantity for the body to utilize at once and so the excess calcium ends up circulating in the blood leading to the circulatory issues described above. This evidence lead to the general recommendation that:
Calcium be consumed from dietary sources
Calcium be consumed slowly throughout the day so as to not overwhelm the system.
Where needed, much smaller dosage of supplemental calcium (150-500mg) can be added (ex. pregnancy, lactation, menopause, osteoporosis).
Finally, when it comes to bone health, we now know there is so much more than meets the eye. Here are just a few factors that can affect calcium absorption and bone density:
Poor absorption from certain foods
Age
Low stomach acid
Low dietary fat
Low dietary protein
A diet high in oxalic acids or phytic acids
Vitamin D deficiency (needed for calcium absorption and metabolism)
Vitamin K deficiency (reduces calcification caused by calcium)
Vitamin E deficiency (associated with lower bone density)
Phosphorous in excess of calcium (reduced calcium absorption)
Magnesium deficiency (reduces calcification caused by calcium)
Strontium and Boron are additional nutrients that play a role
Therefore, if you are working on increasing bone density, taking high dose calcium supplements is not a solution. A bone mineral support should be well rounded and include Calcium, Magnesium, Vitamin D at the very least. Research has demonstrated that the ideal ratio of calcium-to-magnesium is 2:1. In addition, Vitamin D should be 600-1000IU. A well-rounded bones support will include the nutrients listed above. The daily dose of supplemental calcium should be less than 500mg.
A better solution for the general population is to get calcium from food where possible! Below is a list of foods that contain calcium. At first glance, it is true that dairy contains the highest concentration of calcium. You could have 1 cup of yogurt, 2 large slices of cheese and have achieved 80% of your daily calcium goal. However, dairy is not an ideal source for all people with close to 20% of the population reacting poorly to cow dairy.. Individuals who are lactose intolerant and other people with food sensitivities or allergies do not absorb dairy well and therefore, will not absorb the calcium. These individuals need to choose non-dairy sources.
The list below is meant to provide you with a guide to obtain 1000mg of calcium per day with or without dairy. Remember, if you are older than 50, post-menopausal or on an estrogen inhibitor, you may need an additional 200-400mg. If you are pregnant or breastfeeding you may need an additional 200-400mg.
References:
1. Anderson, J. et al. Calcium Intake From Diet and Supplements and the Risk of Coronary Artery Calcification and its Progression Among Older Adults: 10‐Year Follow‐up of the Multi‐Ethnic Study of Atherosclerosis (MESA)Journal of the American Heart Association. 2016;5
2. Bolland MJ, Grey A, Reid IR. Calcium supplements and cardiovascular risk: 5 years on. Therapeutic Advances in Drug Safety. 2013;4(5):199-210. doi:10.1177/2042098613499790
3. Maresz K. Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health. Integrative Medicine: A Clinician’s Journal. 2015;14(1):34-39.
4. Wawrzyniak A, Klimczyk P, Woźniak A, Anyżewska A, Leonkiewicz M. Assessment of differences in nutrients consumption in women diagnosed with osteoporosis as compared to a healthy control group. Rocz Panstw Zakl Hig. 2017;68(2):143-149.
