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... sodium in the water surrounding it. Ninety-nine percent of the calcium is in bone. Bone responds to acid by chemical reactions with the rapid release of carbonate, citrate, and sodium from the hydration shell (Barzel 1051). Therefore, in response to chronic acid stress such as an acid-ash diet, cellular responses mobilize bone and calcium as a buffer. As the result, more calcium will be reserved from bone, and excreted in urine.
The effects can be mild in temporary cases, such as hypercalciuria, and detrimental in long-term conditions, such as osteoporosis in older men and women. The following example will give a simple explanation about how the body's contributions of buffers help greatly in maintaining the body's pH. In a cola drink, phosphoric acid is one of the components that keep it from deteriorating. The pH of cola is about 3. 0, ranging from 2. 8 to 3. 2. The human kidney can excrete urine with a pH no lower than 5. Therefore, if one ingests and fully absorbs a beverage with a pH of 3, one has to dilute it 100 -fold to achieve a urinary pH of 5.
Thus, a can containing 330 mL of cola would result in 33 L of urine! This does not happen because the body buffers the acid of the soft drink. However, if a diet that is high in PRAL is continued, the body will excrete calcium as one of the buffers, thus increasing risks for urinary calcium excretion and hypercalciuria (Barzel 1053). EFFECTS OF HYPERCALCIURIA ON OLDER WOMEN: As discussed above, excess protein intake will cause temporary hypercalciuria.
However, if the process is prolonged, it can have detrimental effects on humans of all sexes and ages, especially among women and older people. For instance, a 50 -mg increase in urinary calcium loss per day will result in an 18. 25 -g loss per year, or 365 g over 20 years. Because the average adult female skeleton contains 750 g calcium at its peak, this is a loss of one half of total skeletal stores! For a male with a store of 1000 g calcium, this is about one third of the total (Munger 147 - 52).
For instance, a prospective cohort study was designed with 1035 white women aged greater than 65 years. Protein intake was measured by using a food-frequency questionnaire, and bone mineral density was measured by dual-energy X-ray absorptiometry (Sellmeyer 118 - 20). Results showed that bone mineral density was not significantly associated with the ratio of animal to vegetable protein intake. However, women with a high ratio had a higher rate of bone loss at the femoral neck and greater risk of hip fracture than those with a lower ratio.
The study showed that elderly women with a high dietary ratio of animal to vegetable protein intake have more rapid femoral neck bone loss and a greater risk of hip fracture than do those with a low ratio. This suggests that an increase in vegetable protein intake and a decrease in animal protein intake may decrease bone loss and the risk of hip fracture among older women. The study has showed evidences of how diets that are high in animal proteins can have adverse effects on aging women. Also, as mentioned in the mechanism section of this paper, consumption of fruits and vegetables can prevent calcium excretion, thus, reducing the risk of bone fractures and osteoporosis in older women. To conclude, high level of protein consumption is dangerous, and these facts should be acknowledged to all individuals, especially to the older women as soon as possible because if hypercalciuria is left unchecked, bone loss may continue and the process can be harder to stop. The following figure 1 and 2 demonstrate the increasing rate of hip fracture and bone loss as the ratio of animal to vegetables protein diets increases (Sellmeyer 120 - 122).
EFFECTS OF HYPERCALCURIA ON OLDER PEOPLE: Dietary protein not only adversely affects women but also the elderly. With aging, the glomerular filtration rate falls and the kidney's ability to excrete this dietary acid load is impaired. This explains why aging kidneys cannot generate ammonium ions and excrete hydrogen ions as well as the young kidneys do. Thus, otherwise healthy individuals develop progressively increasing blood acidity and decreasing plasma bicarbonate as they age.
Because urinary excretion of acid is insufficient, other homeostatic systems, such as bone, buffer the excess dietary acid load. Chronic metabolic acidosis leads to base being liberated from bone to restore acid-base balance, but accompanying minerals, including calcium, are wasted in the urine. This calcium wasting generates a progressive decline in bone mineral content and bone mass (Tucker 245 - 7). In addition, acidosis directly stimulates osteoplastic activity and inhibits osteoplastic activity. Even mild acidosis can have profound effects: if bone is mobilized to buffer only 1 mEq of acid each day; 15 % of the total body calcium in an average person is lost in a decade.
Moreover, parathyroid hormone (PTH) levels are higher in older adults. PTH influences plasma bicarbonate as well as it does to plasma phosphate levels. The total buffering capacity is decreased when PTH is elevated. Overall, it can be concluded that the elderly cease renal ability to excrete free acid, as well as elevated PTH, promoting acidosis. As the result, older people require more buffer than younger people for the same dietary acid load (Tucker 248 - 9).
In summary, a diet high in acid-ash protein causes excessive urinary calcium loss because of its acid content, and hypercalciuria is directly related to urinary net acid excretion. Alkali buffers, whether chemical salts or dietary fruits and vegetables, reverse this urinary calcium loss. Therefore, in order to reduce the risk for hypercalciuria, one must consume fewer foods that are high in animal protein and more fruits and vegetables. CONCLUSION: With prolonged life expectancy and the increasing number of elderly, it is predicted that osteoporosis fractures will reach epidemic proportions. Therefore, osteoporosis prevention and treatment remain of high priority in the latest health goals for the United States. A substantial effort is being made toward understanding the effect of nutrients, particularly protein and calcium, on bone growth during youth and bone loss during aging.
A wealth of new knowledge is now available. Osteoporosis is a serious disorder, and, despite the considerable influence of heredity, bone health depends on the whole range of other nutrients and foods as well as the environmental factors. The prolonged deficiency or excess of one or the combination of several, as well as the changes in requirements of those nutrients caused by physiological and metabolic changes, might contribute to osteoporosis. It is also necessary to account for the interaction between different factors, nutritional, environmental, life style and heredity, to understand the complexity of bone, development of osteoporosis and subsequent fractures. Although our understanding of nutrients and other components affecting bone health continues to grow, the process of acquiring knowledge is not over. Referring a famous quote: "Truth is seldom pure and never simple, " we realize that what is considered a truth now might change, but as long as we keep with our quest, the more certain we will become that what we know is true.
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Research essay sample on Excess Dietary Protein And Calcium
