Bess Dawson-Hughes, a professor of medicine at Tufts University School of Medicine in Boston, has written extensively on the factors that predispose aging people to falls and fractures. The November issue of the Nutrition Action Health Letter has an interview with her that summarizes her current advice.
Loss of bone and muscle mass: She points out that we lose bone and muscle mass as we age, and also the ability to keep our balance. This predisposes us to falls and fractures. The common dietary factor in bone and muscle loss is the ‘acid load’ in our diet, contributed by protein and grains. When these foods are metabolized, they release sulfuric and other acids into the bloodstream. Because of declining kidney function, older people don’t handle the acid load in these foods as well as they did in their youth, and therefore their blood pH becomes slightly more acidic. Normal human arterial blood pH is between 7.35 and 7.45; as you recall from chemistry, a lower level of your blood pH would mean a more acidic fluid. Since aging kidneys can be less effective in regulating pH, our bodies break down bone and muscle to neutralize the acid. However, protein is needed to build strong bones and muscles. Your target protein in grams is roughly half your weight in pounds. A table to calculate the protein content in foods you eat is found at http://www.herbalvitality.info/list-of-high-protein-foods.htm. We should cut down on excess protein and refined grains to reduce our acid load, according to Dawson-Hughes.
Fruits and vegetables in the diet have an opposite effect, since they are broken down into alkaline products that help to neutralize acids. This includes fruits that may taste acidic, like citrus. Sugars and fats are generally neutral with respect to pH. Dawson-Hughes suggests that people really maximize produce – she suggests 9 to11 servings a day to neutralize excess acids! A serving of cooked vegetables is a half-cup, and of salad greens is a full cup. Such a diet is possible, but would take planning, and would not fit into some people’s budgets or work schedules. I will outline a plan at the end of this column.
Potassium bicarbonate (KHCO3) Because of the difficulty of her recommendations, Dawson-Hughes is working on finding the appropriate amount of KHCO3 that could be taken to neutralize excess acids. KHCO3 is an alkalinizing agent. She found, in one small study, that women taking KHCO3 had reduced markers of bone turnover and muscle wasting, and performed better on a leg press at the gym. However, she cautions people not to take KHCO3 at present, as the right dose has not been found, and too much potassium in supplements can be dangerous to people with compromised heart and kidney function.
Exercise is vitally important in maintaining bone and muscle strength. Dawson-Hughes, and many other experts, advises at least 30 minutes a day of weight-bearing exercise like walking or dancing. Strength training is also necessary; you can read Miriam Nelson’s book Strong Women Strong Bones and find an excellent guide to building muscle and bone.
Vitamin D is another key to building strong bones. Dawson-Hughes, and many other experts, advise that people over 60 take supplemental Vitamin D – about 1000 IU daily, in order to keep their blood levels of D at 30 nanograms per milliliter.
Calcium is essential for bone building, and must be accompanied by adequate Vitamin D. Dawson-Hughes has suggested about 800 mg per day, from food and supplements.
Salt in the diet contributes to bone loss. When the kidney gets rid of excess salt, it also excretes calcium that is leached from bones. Here is another reason for a diet lower in salt.
How to maximize fruits and vegetables without going crazy: Along with your other foods, try the following: 2 fruits for breakfast, say an orange, or orange juice, and a banana. Mid-morning – a glass of low-salt Very Veggie or V8. For lunch include a carrot and a tomato, or have vegetable soup. Mid-afternoon – an apple, or raisins or dried figs (both very alkaline). Dinner – include a salad and a cooked vegetable, and a fruit desert. That makes 9. Another glass of Very Veggie or low salt V8 will take you close to the top!
Sadja Greenwood, MD, MPH back issues on this blog