Our bodies require more calcium than any other mineral. Our bones contain 98% of our calcium stores, our teeth 1% and the remaining 1% is a vital element in blood clotting, neurotransmission, digestive enzyme activity, insulin secretion, regulating heartbeat and muscle contraction. It is an essential ‘macromineral’ – required in large quantities – and a critical nutrient during pre conception, pregnancy and breastfeeding.
The importance of calcium absorption factors
There are two aspects affecting your body’s calcium levels. First is calcium intake and second is how well your body can absorb this calcium. Calcium absorption is the most important consideration, because this governs the amount of calcium available to the body for bone mineralisation and other key functions. For this reason it can be counterproductive to simply take a high dose calcium supplement. There are health risks associated with elevated blood calcium levels, so it’s important not to over-supplement.
If your calcium absorption is poor, random self-prescribing of calcium supplements may lead to significant amounts calcifying out of solution and forming deposits in the wrong places, such as kidney stones, arthritic plaques accumulating in heart valves and restricting blood flow, or bony spurs. These can be painful and they are symptomatic of a biochemical imbalance in the body, and particularly of low levels of absorbed calcium. They can indicate underlying problems with heart and bone health due to inadequate calcium being absorbed where it’s most needed.
Muscle spasms and cramping, eyelid twitching, menstrual cramps, backaches, migraines, constipation and heart flutters may all be symptomatic of calcium overload, particularly in ratio to magnesium.
Calcium needs other nutrients to metabolise it effectively, and any form of calcium supplement needs to provide these metabolic co-factors for optimum absorption.
What happens if I don’t absorb enough calcium?
Osteoporosis is the condition most people associate with poor calcium absorption. It’s a condition where bone density decreases and the spaces within the bone increase. This weakens the bones and this fragility is more likely to lead to their collapse or fracture.
Post menopausal women and elderly people are the population groups generally linked with osteoporosis, but they’re not the only ones at risk. Other factors that increase your risk of having osteoporotic bones are:
- If your alcohol intake is high or you’re a smoker
- if you have a high caffeine intake
- if you don’t eat much protein
- if you don’t get much exercise or have limited exposure to sunlight (for vitamin D)
- Estrogen deficiency and hyperthyroidism can accelerate osteoporosis
- Some medications also increase the risk.
During pregnancy if your body doesn’t absorb enough calcium to provide for both your needs and the developing baby, the needs of the baby take precedence. Calcium will be leached from your bones to strengthen baby’s growing bones and teeth, heart, muscles and nervous system. Calcium deficiency during pregnancy can cause heart defects in the baby and increase the risk of preeclampsia, preterm delivery and low birth weight.
Other symptoms of calcium deficiency can include:
- muscle spasm
- weak bones and teeth
- menstrual pain
- delayed growth in children or delayed puberty
- unhealthy skin, hair and nails
- becoming easily fatigued
Maximising calcium absorption for optimal health
Too much dietary fibre, sodium, and caffeine can reduce calcium absorption. Essential to correct calcium absorption are adequate levels of:
- hydrochloric acid production in the stomach
- dietary intake of healthy fats
- vitamin D
Hydrochloric acid production in the stomach is the first influential factor on calcium absorption. If there is too little (a condition common to people eating modern diets) the calcium remains out of solution and cannot be assimilated into the intestines for absorption. This is such an important and prevalent factor in developed countries that it can result in up to 80% loss of available calcium absorption. Excess dietary sodium also inhibits calcium absorption.
Studies have found that when your food intake has a higher ratio of healthy fats to dietary fibre your calcium absorption rate increases.
Vitamin D (as calcitriol, regulated by the parathyroid hormone) regulates intestinal calcium absorption, controlling how much is converted into bone. Our bones are the body’s reservoir of calcium stores. If dietary calcium intake is inadequate then Vitamin D signals the body to increase calcium absorption from the small intestine and to release calcium from bone to maintain blood calcium levels.
Osteoporosis may develop if bone loss is accelerated.
Research indicates that getting the calcium and vitamin D balance right can boost male fertility, an important factor in preconception health. Recent studies reveal up to 40% of the New Zealand population gets insufficient levels of vitamin D, indicating supplementation may be required.
Read more about Vitamin D – here.
The balance of magnesium to calcium is vital for healthy function and particularly to prevent calcification and calcium deposits forming everywhere from the microcellular level through to tissues and organs. A ratio of no more than 2:1 calcium to magnesium is needed by the body for optimal functioning. Although a 2:1 ratio is the conventional standard used for mineral supplements, the ideal ratio for the human body is closer to 1:1 calcium to magnesium.
Read more about Magnesium – here.
Adequate levels of the trace mineral boron (found in fruits, vegetables and nuts) have been shown in a study of post menopausal women to prevent calcium loss and bone demineralisation.
Silica is important because it enhances absorption of all other minerals in the body, particularly remineralisation of bones and all structural tissues in the case of calcium. As we age our silica levels decline. Good food sources of silica include raw oats, oatstraw tea, horsetail tea, beetroot and alfalfa. Women having babies at a later age may need to supplement silica as part of their nutrition plan.
Low Vitamin K intake is linked to increased risk of osteoporotic fracture. Vitamin K is required for formation of osteocalcin, the calcium-binding bone matrix protein.
What is the recommended total daily calcium intake?
These figures are the NZ minimum recommendations for total calcium intake from all sources. Children need plenty of calcium rich food in their daily diet to provide for a growing skeleton, especially through their teenage years. Children’s recommended daily intake guidelines are 500 mg from 1 – 3 yrs, 700 mg from 4 – 8 yrs, 1000 mg from 9 – 11 yrs and teenagers 1300 mg from 12 – 18 yrs. 1000 mg per day is generally recommended for adult women up to menopause, and men up to age 70.
Calcium intake in pregnancy is most important for teenage mums – because their bones are still growing they have a high need for calcium and so does the baby’s developing skeletal system. For women over 19 years if your calcium intake is already adequate it needn’t increase during pregnancy as your body will naturally absorb and retain more to meet the baby’s needs during pregnancy and breastfeeding. The NZ RDI is therefore 1300 mg per day for adolescent mums and 1000 mg per day for those 19 yrs and over.
Increasing the daily intake to 1300 mg is the official recommendation for women after menopause and men over age 70 because the general view is that calcium needs increase for these population groups due to reduced bone density. However, be cautious about this approach. Some studies show bone calcium loss in these groups is caused by postmenopausal estrogen deficiency, or vitamin D deficiency due to parathyroid over-activity in later life. The issue is not low calcium intake, but instead a change in calcium metabolism. With less estrogen in the body to influence bone calcium retention, or too much parathyroid hormone retaining serum calcium, bone calcium is lost into the bloodstream and deposited as calcium plaques in arteries and soft tissue. Increasing your calcium intake as you age may just increase the tendency to form plaques, because there is already excess calcium in the blood.
Are you getting adequate bioavailable calcium from your regular dietary intake?
If you need more calcium food is definitely your best source and the recommended way to increase your intake. The range of foods containing good bioavailable sources of calcium is not as limited as you might think.
Excellent calcium rich foods include bony fish, figs, dates, beans and other legumes, nuts (esp. walnuts, pecans, hazelnuts, brazils, almonds), seeds (sesame, chia, sunflower), carob, green leafy vegetables (kale, broccoli, bok choy, collards, mustard greens, watercress), asparagus, avocado, seaweeds and cereals. Tahini, hummus, miso, brewer’s yeast, blackstrap molasses and tinned salmon or sardines are all calcium rich products recommended as part of your regular dietary intake. Many of these non-dairy sources contain the right proportion of magnesium needed by the body for optimal calcium absorption.
Milk and milk products are rich sources, and some of us absorb roughly a third of the calcium they contain – but many others are deficient in the enzyme lactase, needed to digest the lactose in milk. Those who are lactose tolerant in early life often produce less lactase as they age, reducing their ability to tolerate much dairy product. This causes gastric disturbances which inhibits absorption of calcium (and other nutrients). For people who are lactose intolerant fermented milk products like cheese and yoghurt may be tolerated, particularly goat milk products.
A comparison of world mortality rates from cardiovascular disease indicates
countries with high consumption of dairy products – including New Zealand, USA and Scandinavian countries – have correspondingly high mortality rates. Japan and Portugal have the lowest dairy consumption rates and amongst the lowest mortality rates from heart disease.
Fortified cereals and breads supply extra calcium but the phytic acid they contain inhibits absorption, as does a high fibre diet or high caffeine consumption. Beans, nuts and seeds naturally have relatively high phytic acid content but traditional cooking preparation methods can mitigate its effect.
How do you know if your calcium levels are low?
A blood test doesn’t reliably measure your body’s calcium levels as most is stored in the bones. A bone density test using a special form of x-ray will identify any calcium depletion, however if you’re attempting to conceive or already pregnant, you won’t want to expose yourself to radiation.
A naturopath can assess your need for a calcium supplement along with the other nutrients needed for balanced biochemistry and optimum mineralisation.
What is the best form of supplementation?
There’s a lot of debate and research into the form of calcium supplement that is best absorbed by the body. It’s important to remember that our bodies regulate calcium absorption according to need and influenced by any imbalance in our biochemistry – the ratio of nutrients in relationship to each other present in the body.
The best form of supplementation provides a balanced, bioavailable mineral formula, and focuses on enhancing our body’s absorption rate of calcium from food sources. It is not advisable to take a stand alone calcium supplement over the long term without professional guidance.
Are there any other risks involved with calcium supplements?
Some calcium supplements may be sourced from raw material containing heavy metals and are best avoided. Some are sourced from large rock quarries or vacuumed up from the ocean floor using methods that destroy much of the surrounding environment. I recommend you look for a sustainably harvested and certified organic supplement to provide the best calcium for your body with the least cost to the environment.
By Carolyn Simon
http://www.ajcn.org/content/72/2/466.full – Calcium Absorption
http://www.internetwks.com/owen/TruthCal.htm – Calcium Overload
http://www.ncbi.nlm.nih.gov/pubmed/7840072 – Boron
http://www.lef.org/magazine/mag99/mar99_abs.html – Boron
http://www.healingwithnutrition.com/odisease/osteoporosis/calcium_estrogen.html hydrochloric acid
http://jn.nutrition.org/content/134/3/568.full – Protein
http://www.lewrockwell.com/sardi/sardi175.html – Estrogen and Calcium
http://www.ncbi.nlm.nih.gov/pubmed/11706280 – Vitamin K
http://www.ajcn.org/content/42/6/1197.short – Yoghurt Safe in Lactase Deficiency
http://www.medterms.com/script/main/art.asp?articlekey=6201 – Lactose Intolerance
http://www.vivo.colostate.edu/hbooks/pathphys/digestion/smallgut/lactose_intol.html – Lactose Intolerance
http://healthlibrary.epnet.com/GetContent.aspx?token=e0498803-7f62-4563-8d47-5fe33da65dd4&chunkiid=21616 – Boron