Dietary Supplements Mini Series: Part 1 Calcium

I've been asked on numerous occasions whether or not multivitamins or supplements are needed during training. My response is two-fold. If you have no malabsorption or food allergy/intolerance issues then I feel you can get all nutrients through food. However, if you have and medical issues such as dysmenhorrea or any food allergy/intolerance where absorption of certain nutrients is impaired, then a supplement may be needed. Individuals who are lactose intolerant most likely need a calcium supplement while those with dysmennhorea may need an iron supplement. But what are the food sources of calcium and iron and how do you know what type of supplement to buy? This mini-series will answer those questions and inform you of how much you should be taking in each day.

Part 1: Calcium

Calcium intake is important for athletes for maintaining proper bone health and preventing stress fractures. We reach our peak calcium content by age 30 and after that slowly begin to lose calcium stores. This can be mitigated in two ways, through proper dietary calcium intake and also through exercise, specifically running or walking and weight training. When not meeting the dietary calcium needs, while in the short term, too little calcium intake will not cause harm, a long term deficiency can put you at risk for osteoporosis and stress fractures. But how much calcium do you need? The chart below is the recommended daily amounts of dietary calcium intake.

Life Stage Recommended Amount

  • Teens 14–18 years 1,300 mg
  • Adults 19–50 years 1,000 mg
  • Adult men 51–70 years 1,000 mg
  • Adult women 51–70 years 1,200 mg
  • Adults 71 years and older 1,200 mg

You can meet your calcium needs through food sources and that is always the best option however certain groups of people are at risk for not meeting the daily recommended needs. Those groups include a food allergy to dairy or lactose intolerance, postmenopausal women and women who have amenorrhea (absence of the menstrual period because of heavy exercise, restricting food intake or both). Other factors affecting absorption include too little Vitamin D intake and vegetarians with high intakes of oxalic acid (dark leafy greens, rhubarb, soy and cocoa) and phytic acid (in whole grains and wheat bran) can reduce calcium absorption.

Calcium decreases the absorption of certain drugs (bisphophonates, thyroid, some antibiotics). Other drugs can increase calcium needs (corticosteroids, some diuretics). It’s best to check with your doctor to determine if any of your medication interferes with any supplement use.

Fortunately for those who are lactose intolerant, there are also alternative dairy products that can help meet calcium needs. This includes Lactaid milk and soy, rice or almond milk. Also, Greek yogurt is typically well tolerated in those with lactose intolerance. When it comes to comparing cow’s milk or soy or almond milk products, cow’s milk contains 300 milligrams of calcium per 8-ounce cup whereas soy or almond milk contains 450 milligrams of calcium per 8-ounce cup. While milk, yogurt and cheese are the main sources of calcium in the typical diet, other sources include vegetables such as kale and broccoli or fish with soft bones such as canned sardines and canned salmon. Calcium has also been fortified in many of the foods we eat so looking at the food label to determine the amount is important.

But do you need a calcium supplement? Ask yourself the following:

  1. Are you lactose intolerant?
  2. Are you an ovo-vegetarian?
  3. Do you consume less than the recommended 3 servings of dairy each day?

If you answered yes to any of these questions, a calcium supplement may be right for you. But then the next question is which one to choose? Calcium supplements come in many forms to include calcium carbonate, citrate, citrate malate, phosphate, gluconate and lactate. The two most common forms are calcium carbonate and citrate. Avoid supplements made of dolomite, oyster shell and bone meal as they may contain metals and lead. Calcium phosphate, calcium lactate and calcium gluconate are not generally recommended because they contain very small amounts of calcium.

The upper limit should not exceed 2,500 milligrams per day. A risk factor of excess intake is kidney stones. Note if you are meeting the daily recommended intake needs, you do not need to increase intake if training. These supplements provide 250 to 1,000 milligrams of calcium often added with Vitamin D and magnesium to increase absorption. When reading a supplement label, the amount of calcium to pay attention to is the elemental calcium. This is because during digestion, the elemental calcium is released from the compound (carbonate, citrate) and is what becomes available for absorption. The number that is part of the brand name (such as Caltrate 600, Os-Cal 500 and TUMS 500 Extra Strength) usually indicates the amount of elemental calcium in each tablet. However, make it a habit of reading the label to be certain. If the label does not state elemental calcium, assume the elemental calcium is 40 percent from carbonate and 21 percent from citrate. This means if the label states it provides 1,000 milligrams calcium carbonate; it actually contains 400 milligrams elemental calcium.

The two most common types of calcium supplements on the market are calcium carbonate and calcium citrate. Calcium carbonate is cheaper and best absorbed when taken with food because it requires stomach acid to dissolve and be absorbed. This type, since it contains the most elemental calcium per tablet (40 percent), fewer tablets are needed. However, a side effect of calcium carbonate is constipation. Common types of over-the-counter calcium carbonate supplements include Viactiv Soft Calcium Chews with vitamins D & K, Tums 500, Caltrate 600 and Os-Cal 500.

Calcium citrate is well absorbed on an empty stomach and does not cause constipation, however it typically is more expensive. This option may be a better choice for older adults who have a lower stomach acid level. The downside is it contains less elemental calcium per pill (20 percent). Common types of calcium citrate include Citracal, Citracal with vitamin D (315 mg), TwinLab Calcium Citrate Caps (300 mg), some calcium-fortified orange juice (but not all), Solgar Calcium Citrate (250 mg) and Citrical Ultradense Calcium Citrate Tablets (200 mg).

If you have do not have any issues with stomach acid and digesting calcium carbonate, I’d recommend this type of calcium supplement due to its increased amount of elemental calcium and lower cost. However if it causes constipation, switching to a calcium citrate supplement may be a better option for comfort on a personal level. When taking any calcium supplement, it is best absorbed 500 milligrams at a time so space out the pills or tablets. Vitamin D also enhances calcium absorption, so make sure to get 400 to 800 international units (IU) of vitamin D per day. Most calcium supplements contain Vitamin D to enhance its absorption.

When taking any dietary supplements check for a USP (United States Pharmacopeia) symbol on the label which means the calcium supplement is free of lead and other metals. It also meets standards for quantity of elemental calcium in the tablet and how well it dissolves. The application for this symbol is voluntary, so a product may be acceptable even if it does not display this symbol. This is because dietary supplements are not regulated by the Food and Drug Administration (FDA) and third party companies such as USP provide standards for these supplements.

Key points to keep in mind when looking for calcium supplements:

  1. Is it necessary – are you taking in enough calcium through your diet?
  2. When looking at supplements, calcium carbonate contains more elemental calcium and therefore will be better absorbed by the body, usually taken with food and cheaper to purchase, however causes constipation and harder for people with low stomach acid to tolerate.
  3. Calcium citrate contains a lower amount of calcium your body will absorb and is typically more expensive but can be taken on an empty stomach.
  4. Check with your doctor if you are taking medications that can cause problems if taking a calcium supplement.
  5. Take the supplement in 500 milligram increments at a time to increase its absorption.
  6. Calcium is better absorbed when taken with vitamin D; most supplements contain this for optimal absorption.

Exercise to include walking or running and strength training will also help with preserving bone density loss. For an exercise program check out a respected friend and phenomenal athlete Dennis Welch Coaching and Consulting on Facebook!


Office of Dietary Supplements, National Institute of Health (

Sarubin-Fragakis A. The Health Professional’s Guide to Popular Dietary Supplements, 3rd ed. Chicago, IL: American Dietetic Association, 2007. ISBN: 9780880913638