CALCIUM ABSORPTION

Q. Can you clarify when is the best time to take calcium. I have heard it can't be absorbed on its own, and also that it can't be absorbed with food. Osteoporosis runs in my family and I am soon to be a postmenopausal woman. I want to make sure I am getting the most out of my calcium supplement.

A. There are a few supplements out there that really need to come with an instruction manual, rather than just a suggested dosage. Calcium is one of these nutrients. Especially for ageing adults, it is so important to understand how to most effectively supplement with calcium in order to make sure you are protecting yourself against osteoporosis and fracture.

The Role of Calcium in the Body
Although 99% of our calcium is stored in bones and teeth, the other 1% has quite a significant job to do throughout the body. From supporting the contraction and dilation of our vasculature, to playing a significant role in nerve transmission, muscle function and even hormonal secretion, calcium is vital to our body's ability to function. Serum or blood calcium levels are tightly regulated because of this. These levels do not fluctuate with dietary changes or intake. The calcium content of bone, however does.

Breakdown
Continuous remodelling of bone is a normal and healthy process. We are constantly breaking down and depositing calcium into bone. During childhood and adolescence, formation of bone exceeds breakdown, but by the time we are aging adults, this process of remodeling is much less efficient and we begin to breakdown more than we are able to form. This relative increase in bone loss puts these individuals at a higher risk for osteoporosis and fracture. It also makes diet and potentially supplementation so important for this population. Similarly, for those individuals who are lactose intolerant or possess a dairy allergy, vegans, and even those with increased need based on situation, such as during pregnancy, calcium supplementation may be required in order to ensure adequate intake.

Carbonate or Citrate – form does matter!
So, now that we know why we may need to supplement, let me get to your question; how best to supplement with calcium? First off, the reason you are getting mixed messages in terms of whether to take your supplement with or without food, may be based on the type of calcium you are referring to. Calcium carbonate, often the most commonly seen and cost effective forms of calcium on the market, must be taken with food. It tends to be somewhat more difficult to absorb than other forms. Calcium carbonate is often not recommended for older individuals or those with low stomach acid, as it can neutralize stomach acid further. For these individuals, calcium citrate is a far easier form of calcium to absorb and this form can be taken with or without food. It does tend to be slightly more expensive than the carbonate form. Other forms of calcium you may see on your healthfood store shelf include calcium citrate/malate, calcium bisglycinate and calcium formate (all of which have a high absorption rating), as well as calcium lactate and calcium gluconate. These forms are often found in liquid calcium formulas and do tend to have a slightly lower absorption rate than other forms.

500 mg is the Magic Number
Another important aspect of ensuring the most effective calcium absorption is to consider how much you are taking at one time. Absorption of calcium is highest at dosages of 500 mg or less. For those individuals who are supplementing with more than 500 mg/day, it is very important to spread this intake throughout the course of the day, optimally allowing for 4-5 hours between dosages. There is also some evidence to suggest that calcium is better absorbed at night. I often recommend saving one dose for just prior to bed, especially if you are combining your calcium with a magnesium supplement. These minerals have the added bonus of helping to support sleep through muscle relaxation and calming of the nerves.

...And Best Supporting Role goes to Vitamin D
There are other vitamins and minerals that also help to support calcium absorption, perhaps none being as important as vitamin D. Vitamin D status will effect how well calcium is absorbed in the body. Making sure your vitamin D levels are adequate, and supplementing with D if they are not, can help improve calcium absorption.

Nutritional Interactions
For those of you who are combining their calcium supplements with foods, be aware that there are some interactions that could be affecting optimal calcium absorption. High sodium diets cause in increase in calcium excretion. Adding some extra potassium into your diet, especially for post menopausal women, can help to fight this effect. Caffeine, fibre, and alcohol can all serve to reduce absorption and/or increase excretion of calcium. Use these in moderation and try to keep them separate from calcium supplementation. Phytic and oxalic acids in the diet can also inhibit calcium absorption. Spinach, collard and beet greens, cranberries, plums, sweet potatoes, rhubarb and beans all contain phytic acid. Beans, nuts, seeds, soy isolates and some wheat bran and whole grain products contain oxalic acid. Although research has shown that whole grain products do not appear to decrease calcium absorption significantly. Soaking your grains, legumes, nuts and seeds can also help to reduce these acid levels, minimizing the effect these foods have on calcium absorption.

pH
Acid/base balance can also have a significant impact on calcium absorption. Diets high in fruit and vegetables, as well as greens such as chlorophyll and spirulina, shift the acid/base balance to a more alkaline environment, thus decreasing calcium loss. On the other hand, diets high in animal protein, sugar, and refined grains force bone to release minerals like calcium, in order to buffer the blood and neutralize excess acid. Individuals who are finding that they are losing bone mineral density while supplementing with calcium need to be aware of the importance that their pH has on overall calcium balance.

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