Good bone health affects your ability to stay active and healthy throughout life. However, when female athletes, especially those training for recreational or elite athletic competition, knowingly or unknowingly exercise too much and eat too little, they may be at risk for low bone mass and fractures.
The incidence of low bone density and stress fractures, is increasing among competitive and recreational female athletes of all ages, and leads to pain and lost time from training and competition. Osteoporosis, a bone disease caused by weakened, porous bone, occurs silently and progressively over time, often with no symptoms until a fracture occurs. It’s currently estimated that one in three women over the age of 50 will suffer from an osteoporotic fracture www.iofbonehealth.org.
Bone is a living tissue that is constantly changing. Nutrition, physical activity, and certain hormones all play a role in the development and maintenance of healthy bones. With adequate nutrients, in particular calcium, Vitamin D, and protein, as well as weight-bearing exercise, most people achieve a peak bone mineral density by their late 20’s. During the normal aging process, both bone mass and bone strength decrease, with increased declines related to the lack of estrogen, such as with menopause or in female athletes with amenorrhea. Therefore, bone disease prevention begins during childhood and adolescence, as well as lessening the extent of bone loss that occurs during the aging process.
To optimize bone health, female athletes need to:
- Consume foods that provide adequate calcium and vitamin D
- Eat enough calories to support their training
- Include high quality protein at meals and snacks
- Participate in strength or resistance exercises that provide an mechanical force on the bone
- Recognize that menstrual irregularity is a warning sign for low bone mass – and for postmenopausal women, consider having a DEXA bone density scan done to measure your bone density.
The Role of Calcium and Vitamin D
Calcium is an important mineral in the body for maintaining bone strength, regulating muscle contractions, maintaining blood pressure, and transmitting nerve impulses. Most of the body’s calcium is stored in our bones (and teeth); and, without enough calcium each day from the diet, the body will use what it needs from the bone to keep blood calcium levels normal. If more calcium is removed from the bones than is consumed in the diet, the bones may become fragile or weak.
The calcium recommendation for women ages 25 to 50 is 1,000 to 1,200 milligrams per day and 1,200 mg/day for women after age 50. Good sources of calcium include dairy products (milk, yogurt, kefir, and cheese), calcium-fortified juices or plant milks, some types of tofu, certain vegetables (collard greens, kale, broccoli, bok choy), oranges and almonds.
Vitamin D is also vital to bone health as it is needed for the absorption of calcium from the intestines and plays a key role in bone mineralization. The recommended daily allowance is 600 international units (IU) for those women under 70 years of age and 800 IU for those over 71 years of age. Vitamin D is present in only a few foods including fatty fish, egg yolks and fortified foods, like milk and cereal. It is also made in the skin when exposed to sunlight. For those unable to get sunlight or consume sufficient Vitamin D from foods, 2,000 units of Vitamin D daily may be recommended, but you should consult with your doctor before taking any supplement.
Other Key Nutrients for Bone Health
Consuming enough calories to fuel activity and other body functions is critical. Eating a variety of foods at three meals and two to three snacks throughout the day according to your hunger and fullness will generally meet the energy demands of your sport.
Including a source of protein (lean meat, fish, dairy products, soy foods, beans, legumes and nuts) at each of your meals and snacks will provide the building blocks necessary for building a strong matrix of protein fibers in bone. Achieving peak bone mass during childhood and adolescence, as well as preserving bone mass with aging, is dependent on the body having enough protein available for bone development.
Many other nutrients are needed for healthy bones. Although research is still evolving on their role and benefits, Vitamin K, magnesium, phosphorus, and zinc also have a role in bone health.
I’m often asked if there is a way to reverse bone loss or if a supplement, like collagen, will help prevent bone loss. There are medications that can help slow bone loss, however these come with side effects. Osteoporosis is not reversable. At this time, there is no evidence to support taking a collagen powder to prevent bone loss. Collagen powders only provide three amino acids that are components of collagen in the body, but there is no way to direct those amino acids to specific tissues in your body (in this case bone) to aid in collagen synthesis. A better strategy would be to consume adequate amounts of high quality protein (such as those foods highlighted above) or include a protein powder that provides the body all of the amino acids (i.e. whey or soy protein).
Bottom line: A food first approach is a superior way to ensure your body is getting all the key nutrients needed for bone metabolism. For advice on customizing a fueling plan, consult a Registered Dietitian who specializes in sports, particularly a Board Certified Specialist in Sports Dietetics (CSSD).