Megan Witt, RD, LD
Strong healthy bones are vital to living a long and productive life. In addition to getting some bone-boosting exercise, you need to get the right mix of nutrients to nourish those bones, while limiting those things that can speed up the breakdown of bone.
Just as muscles respond to exercise, so do our bones. Weight-bearing and resistance exercises that put a little stress on the bone can help maintain and even improve bone density. Walking, aerobics, weight-lifting, jogging, dancing and stair climbing are examples of weight-bearing exercises. Although swimming and cycling are wonderful forms of aerobic exercise, they are not considered weight-bearing because your feet and legs are not bearing your weight.
Ninety nine percent of the body’s calcium is stored in the bones and teeth. Current government guidelines recommend 1300 mg/day for pre-teens and teens, 1000 mg/day for those age 19-50 and 1200 mg/day for women 51 and over. Men 51-70 require 1000 mg/day and 1200 mg/day over 70. In some parts of the world people do well on much less calcium than this, but they are likely getting more exercise and vitamin D and may not be losing excess calcium due to certain dietary and lifestyle habits, such as from smoking and high sugar and sodium intake. Dairy foods contain the highest amounts of calcium. Other sources include fortified juices and dairy alternatives. Almonds, sesame seeds, spinach, collard greens, kale, dried beans, soy and broccoli are some vegetarian sources.
Without vitamin D, calcium wouldn’t be able to do its job. Vitamin D helps the body absorb calcium from the intestines and prevent its excretion from the kidneys. Numerous studies have found increasing vitamin D levels can help reduce the risk of falls and fractures in the elderly. Many people do not receive adequate time in the sun to make enough vitamin D or do not eat vitamin D rich foods. Experts are now recommending most healthy people aim for 1000-2000 IU per day via food and supplements, although some may need more depending on individual needs. Ask your doctor to test your vitamin D levels to get a more accurate determination of your vitamin D status.
Fruits and Vegetables, Acid and Alkaline
While calcium and vitamin D have garnered most of the attention when it comes to bone health, we should note the importance of fruits and vegetables in building strong bones. The typical American diet that is low in fruits and vegetables and higher in sodium, animal protein, and refined grains can lead to an acid-base imbalance by increasing the acid load of the body. More bone loss occurs in this acidic state. A plant based diet increases the alkalinity of the body and leads to less calcium excretion. Alkalinizing foods include vegetables, especially leafy greens, fruits, nuts and seeds. Even though citrus fruits such as lemons, limes, oranges and grapefruits are acidic, they are alkalinizing after they are consumed and metabolized.
A 2009 study published in the Journal of Clinical Endocrinology found that adding an alkaline salt (potassium bicarbonate) promoted calcium absorption, even when consuming a high protein diet. Potassium rich foods provide a natural source of bicarbonates which can help buffer acidic pH levels. The potassium-rich DASH diet is high in fruits, vegetables, low fat dairy and has a low acid load. It is typically encouraged to lower high blood pressure, but it has also been shown to significantly reduce bone turnover which over time may increase bone mineral density and reduce the risk of osteoporosis. ( J. Nutr. October 1, 2003 vol. 133 no. 10 3130-3136)
A 2003 study in the November issue of The Journal of Nutrition found fennel, celery root, prunes, oranges, French beans, mushrooms and red wine residue to significantly protect against the breakdown of bone tissue when compared to other items such as soy, corn, potatoes, tomatoes and spinach. The compound hesperidin, a flavonoid found in citrus, has also been shown to reduce the number of cells that break down bone.
Vitamin K is found primarily in green leafy vegetables such as spinach, kale, broccoli and parsley and in smaller amounts in vegetable oils. It appears to play an important role in bone mineralization.
Numerous studies have found that those with adequate magnesium intake tend to have better bone density than those with a lower intake of magnesium. Scientists believe that having too little magnesium affects calcium metabolism and the hormones that regulate calcium. Aim for 350-400 mg/day. Nuts, beans and grains are good food sources of magnesium. Magnesium can also be found in supplements individually or can be paired up with calcium and vitamin D.
Eighty five percent of the body’s phosphorus is found in bones and teeth. Because phosphorus is found in a wide variety of foods, needs are easily met. There is actually more concern with excess phosphorus consumption. There is a delicate balance between calcium and phosphorus. When phosphorus intake increases, calcium intake should also increase.
Studies suggest boron may help improve bone mass and enhance calcium metabolism in post menopausal women. There is currently no RDA for boron, but the tolerable upper limit is set at 20 mg/day. Boron can be found in nuts, fruits, beans, peas, lentils, milk, eggs and vegetables.
A 2011 study published in the journal Nutrition and Metabolism found that omega-3 fats combined with exercise helped promote bone formation and suppressed bone breakdown in post menopausal women. Omega-3 fats are found largely in oily cold water fish such as salmon, herring, mackerel, sardines and tuna. Walnuts and flaxseed are plant-based sources of omega-3 fats. It is also important to limit excess consumption of omega-6 fats which lead to the production of more compounds associated with bone loss. Foods high in omega-6 fats include most vegetable oils, such as corn, sunflower and soybean oils. Americans tend to consume excessive amounts of omega-6 fats and not enough omega-3 fats.
The following can work against your efforts to build and protect your bones by contributing to bone loss: