INSIDE SPORTS NUTRITION

While the strength of our bones is determined earlier in life, bone loss occurs as a natural part of the aging process. Stress fractures are more common in active females’ due bone related consequences (reduced calcium absorption, and bone mineral density) associated with a higher incidence of Relative Energy Deficiency in Sports Syndrome (RED-S). Furthermore, stress fractures are a common overuse injury in endurance sports due to repetitive mechanical loading. Although there are many nutrients that play a role in bone health, the following nutrition factors may help support bone health, and to aid in recovery and healing from bone injuries. 

Maintaining chronic adequate energy availability (> 45 kcal/kg of lean body mass/ day) is the most important factor for optimal bone health, protection against injury, and to support healing. Reductions in energy availability, especially if chronic, have been shown to reduce hormones (estrogen, testosterone) that are important for bone formation and resorption as evidenced by many Female Athlete Triad and Relative Energy Deficiency in Sport studies.

Protein plays a role in the production of hormones that affect bone health and provide structure for the matrix of the bone. Adequate protein intake (~1.6 to 2.2 g protein/kg of body weight) can help decrease the loss of muscle mass and promote repair. Contrary to previous beliefs, protein intakes higher than the recommended daily intake have no negative impacts on bone health if calcium intake is adequate. In fact, although more research is needed higher protein intakes have been shown to have a small, beneficial impact on bone.

Calcium plays a major role in bone formation, while the bone serves as a storage reservoir for 99% of the body’s calcium. Thus, inadequate calcium intake can impair bone healing. 1500-2000 mg/day has been shown to support healing. Furthermore, one study found that consuming a calcium rich meal or supplement (~1000 to 1300 mg) before exercise can offset sweat calcium losses in endurance athletes.However, more research is needed to determine how much calcium is lost in the sweat. Calcium rich foods include: milk, fortified orange juice, kale, tofu, yogurt, sardines. Calcium intake can be boosted by consuming milk (chocolate, dairy or soy), yogurt, or kefir as a recovery beverage/snack after training.

It has been suggested that active individuals who are vitamin D deficient ( < 50 nmol/L) are at a greater risk for bone fracture. Therefore, it’s important that vitamin D levels are adequate (>75 nmol/L) to support bone health and to help with calcium absorption. Depending on vitamin D levels, supplementation may be needed (especially during the winter months) to ensure levels are adequate. Although sunlight is the best source of vitamin D, dietary sources include fatty fish, sun-exposed mushrooms, sardines, and milk.

Magnesium and Vitamin K also play an important role in bone health. Vitamin K has been associated with an increased fracture risk and a magnesium deficiency may contribute to poor bone health. Therefore, if intakes are below the DRI, supplementation may be needed.

Ideally, good nutrition habits that promote bone health and support the demands of the athlete’s sport should be emphasized during adolescence given that reversing low bone mineral density later in life is difficult.⁹ Active individuals should focus on a “food first” approach prior to reaching for a supplement. A diet containing dairy/dairy alternatives, fruits and leafy green vegetables provides support for bone health. Finally, more research is needed to examine the long-term effects of dietary patterns on bone health in athletes. 

PMID: 30676133, 31696454, 25970439