The Endurance Athlete and Osteoporosis

By Bob Seebohar | Sept. 23, 2009, 12 a.m. (ET)
We have all heard that osteoporosis is a major concern in our society today.  However, what is less commonly known is the alarming increase of endurance athletes with decreased bone mass due to high training volumes and inadequate food consumption (which leads to several nutritional deficiencies).  While it is true that women are affected more than men, it does still happen in males.  In fact, one in every five osteoporosis victims is male.  This article is intended to provide a basic overview of bone health and how it can be enhanced through diet.  There is a wealth of information on this topic, but I have tried to pick the most important issues pertaining to endurance athletes.  Please consult your physician or a registered dietitian for specific recommendations.

What is osteoporosis?
Osteoporosis (porous bone) is defined as “a metabolic bone disease characterized by low bone mass and microarchitectural deterioration of bone tissue leading to enhanced bone fragility and a consequent increase in fracture risk.”  Often called a silent disease, osteoporosis develops gradually over many years before the occurrence of clinical symptoms such as loss of height, curvature of the spine and fractures.  For many individuals, a skeletal fracture is the first indication of osteoporosis.

We can think of our bones as a retirement account, with calcium serving as the money we invest.  We want to start early in order to build up our stores so that we can live more comfortably as we grow older.  Peak bone mass is achieved by our mid 20’s to early 30’s so it is crucial that we invest the most before this time.  A low intake of calcium throughout our teens and early 20’s may predispose us to the development of osteoporosis by reducing achieved peak bone mass and possibly causing age-related bone loss later in life.

The Endurance Athlete

Endurance athletes require large amounts of energy (food) to train and race well.  What is becoming more common is that athletes restrict their daily caloric intake in order to enhance performance, when in fact they should do the opposite.  A decreased caloric intake not only can lead to decreased performance due to low energy stores, but more importantly, restrictive eating patterns have been shown to increase the risk of stress fractures.  It is thought that this is a result of nutritional deficiencies that exist from a low energy intake.

The first rule of thumb is if you are at risk for osteoporosis to not limit your caloric intake because you are worried about performance.  Body weight should never be sacrificed for performance issues.  Maintaining an ideal body weight based on your height, weight, resting metabolic rate, medical and health history, and activity level is important primarily for health reasons and secondarily for performance reasons.  Chronic low energy intakes coupled with high volume training could exacerbate tissue injury thus preventing you from training at all.  It is really not worth the risk.  Obtaining the right amount of daily calories and a variety of food is crucial for longevity.

Dairy Products
As I discussed earlier, there exists a direct relationship between dietary calcium and bone health.  The best source of bioavailable (highly absorbed by the body) calcium is from dairy products such as milk, yogurt and cheese.  In fact, 1 cup of fat free milk has 86 calories and a whopping 302 milligrams of calcium!  Three cups of milk per day supplies almost all of the dietary calcium most of us need.

The recommended intakes of calcium are:

Preteens/Teens (9-18 years)  1300 mg 
Adults (19-50 years)  1000 mg 
Adults (50+ years)  1200 mg 

It is possible to acquire calcium from other food sources but remember that milk, specifically, also contains vitamin D, vitamin A, protein, potassium, riboflavin, niacin, vitamin B12 and phosphorus.  Each of these 9 essential nutrients play a different role in your body to help regulate body processes and maintain good health.

For those of you not too keen on milk, here are some other food sources that contain calcium:

Plain lowfat yogurt, 8 oz.  415 mg 
Cheddar cheese, 1 1/2 oz.  306 mg 
Soft-serve ice cream, 1/2 cup  112 mg 
Canned pink salmon with bones, 3 oz.                           126 mg 
Broccoli, 1/2 cup  47 mg 
Kale, 1/2 cup  90 mg 
Orange, 1  52 mg 
Instant oatmeal, 1 packet  19 mg 
Cafee latte, 12 oz.  412 mg 
Dry roasted almonds, 1 oz.  80 mg 
Corn tortilla, 1  46 mg 
Enriched English muffin, 1  98 mg 

While it is possible to arrange an adequate diet using available Western foods, it is usually difficult to do so without including dairy products.  In general, a diet low in dairy foods means that a diet may be deficient is several respects beyond insufficiency of calcium.  Many times people steer to supplements to acquire the necessary vitamins and minerals because they often believe they do not get the required amount from their diet.  While this may be the case for some people, remember that calcium supplements typically may not be as bioavailable as dairy products, thus your body may not be getting all of the calcium some supplements promise. 

For those of you who are strict vegetarians, the above listed non-dairy foods give you an idea of different choices you can make to ensure adequate intake of calcium.  You may have to eat more of some foods to get the recommended amount of calcium (if you do not consume dairy products) but increasing consumption of some foods, such as fruits and vegetables, has significant health benefits!  Be sure to also choose calcium-fortified foods.  Even though soy products are extremely beneficial to health because of the phytochemicals they contain, they usually do not contain much calcium.  On average, a non-fortified glass of soy milk has about 20 mg of calcium.  So again, choose soy products that are calcium-fortified.

For those of you who are lactose intolerant, it may still be possible to consume dairy products.  Lactose intolerance is not an “all-or-nothing” condition.  Instead, it is a matter of degree.  The amount of lactose someone can comfortably consume depends largely on their own lactase enzyme level.  Tips for those who are lactose intolerant include the following:

  • Start with small servings of dairy products
  • Drink milk with food
  • Try cheese (more than half of the lactose in cheese is removed during processing)
  • Try “friendly” cultures (look for active cultures on yogurt cartons…it will help digest lactose
  • Look for lactose-reduced milk

Take Home Message

Endurance athletes are at high risk of developing osteoporosis later in life due to high training volumes and insufficient energy intake, sometimes leading to nutritional deficiencies.  By including the recommended amount of calcium in your diet (whether it be from dairy products or other foods), you can build up your calcium stores and bone mass thus reducing your risk for developing osteoporosis.

Bob Seebohar, MS, RD, CSSD, CSCS is a sport dietitian and elite triathlon coach.  He traveled to the 2008 Summer Olympics as the U.S. Olympic Committee Sport Dietitian and the personal Sport Dietitian for the 2008 Olympic Triathlon Team.  He is also Sarah Haskins' personal coach and was a performance team member (sport dietitian and strength coach) for Susan Williams, 2004 Olympic Triathlon Bronze Medalist.

Bob's book, Nutrition Periodization for Endurance Athletes: Taking Sports Nutrition to the Next Levelwill provide triathletes of all levels education on how to structure their nutrition program based on their exercise program. For more information, visit or contact Bob at