Diet, Aging, and Muscle by Joe Friel
Popeye was right: eating spinach can make you stronger and more muscular, especially if you're over age 50. Let me explain.
It's apparent that as we grow older muscle mass is lost. Although this loss is slowed somewhat by weight lifting and vigorous aerobic exercise, it still happens. Even athletes in their 60s typically demosntrate considerably less muscle than they had in their 40s.
Now there is research that shows why (1). Nitrogen, which is an essential component of muscle protein, is given up by the body at a faster rate than it can be taken in as we get older. This is due to a gradual change in kidney function that comes with aging producing an acidic state in the blood. Essentially, we are peeing off our muscles as we pass the half-century mark in life.
Also, with a net loss of nitrogen, new muscle cannot be formed. This same acidic state of the blood also explains why calcium is lost with aging resulting in osteoporosis for many, especially women, with advanced age (2).
The key to reducing, or even avoiding, this situation is to lower the blood's acid level by increasing its alkalinity. There are studies demonstrating that taking a supplement called potassium bicarbonate daily for as few as 18 days increases the blood's alkaline level by balancing nitrogen in the body (2,3). While it can be purchased relatively inexpensively in laboratory supply shops, potassium bicarbonate is not currently available as an over-the-counter supplement, and there are no long-term studies of its effects on health. There is some evidence that it contributes to irregular ECG readings.
But there is also a natural way of achieving this same result through diet by eating foods that increase the blood's alkalinity - fruits and vegetables. Fats and oils have a neutral effect on blood acid. All other foods, including grains, meats, nuts, beans, dairy, fish, and eggs, increase the blood's acidity (4). If your diet is high in these latter foods but low in fruits and vegetables, you can expect to lose muscle mass and bone calcium as you age.
