High In Acid Ash Protein example essay topic

INTRODUCTION: Osteoporosis is the major public health problem in the United States because the disease costs million lives and dollars. Osteoporosis, which means "porous bones", is a condition of excessive skeletal fragility resulting in bones that break easily. A combination of genetic, dietary, hormonal, age-related, and lifestyle factors all contribute to this condition. Osteoporosis leads to 1.5 million fractures, or breaks, per year, mostly in the hip, spine and wrist, with the cost of treatment estimated at $10 billion to $15 billion a year, according to the National Institutes of Health. It threatens 25 million Americans, mostly older women and men. One in three women past 50 will suffer a vertebral fracture, according to the foundation (Munger 147).

These numbers are predicted to rise as the population ages. Most causes of osteoporosis are uncontrollable, such as genetics and ages. However, there are also dietary factors and living lifestyles that contribute greatly to the disease. For more than half a century there were studies and research, which showed that that diets high in protein increase calcium resorption from bone and urinary calcium excretion, thus, increasing the risks for osteoporosis and other diseases (Munger 149-52).

First, this paper will give evidences about how diets that are high in protein contents can cause hypercalciuria. Second, it will give the mechanism of how hypercalciuria is caused. Lastly, it will present what types of people are affected by this disease, and how diets high in fruit and vegetables can reverse the process. THE EVIDENCES: There were many researches and studies, which proved that high consumption of dietary protein could lead t urinary calcium excretion, and eventually caused hypercalciuria.

One of those evidences was a study conducted by Dr. Jane Kerstetter at the School of Allied Health. His study concluded that high levels of dietary protein increased urinary calcium excretion and induced negative calcium balance. The experiment had sixteen healthy women (aged 20-40 yr) as participants. The control was a two-week diet containing moderate amounts of calcium, sodium, and protein.

Followed the control was the experimental diet, which was four days long and consisted of one of three levels of protein (low, moderate, or high). On day four, serum and urinary calcium, serum PTH, 1, 25-dihydroxy vitamin D, serum osteocalcin, bone-specific alkaline phosphatase, and urinary N-telopeptide excretion were measured (Kerstetter 1053-4). The cycle of a 2-week adjustment period and a 4-day experimental period was repeated two more times until all subjects received each of the three levels of dietary protein in random order. The study was approved by human investigation committees at both Yale University and the University of Connecticut. After the experiment has been completed, the results showed significant high levels of urinary calcium and N-telopeptide excretion on the high protein diet. The study concluded that a medium protein intake induced no change in mineral homeostasis, intestinal calcium absorption, or bone turnover rates.

However, high levels of dietary protein were associated with increased rates of bone resorption (Kerstetter 1054-5). The following figure compares the excretion of N-telopeptide on day 4 between the low and high protein diet among the young female participants. Furthermore, another cross-sectional study about the correlation between dietary protein intake and calcium excretion was followed by Dr. Itoh, Nirshiyama, and Suyama. The subjects were 349 male and 406 female Japanese age 20-79 years. They were then divided into two groups: those aged 20-49 years and those age 50-79 years. The subjects were free to choose which types of foods to eat and what levels of protein to consume.

The observed data revealed a significant positive correlation between daily urinary excretion of calcium and protein intake in both sexes and in each age group (Itoh 438-50). The positive correlation between calcium excretion and urea excretion implied that, "in this free-living population where dietary patterns and lifestyles were fairly homogeneous, increases in habitual protein intake from self-selected diets enhanced urinary excretion of calcium (Itoh 449)". The calculations estimated that an increase in urinary calcium excretion was 1-2 mg, and 75% of nitrogen ingested as protein was excreted as urinary urea nitrogen. In addition, the study examined whether the calciuric effect of protein depended on the protein source. Evidence showed that animal protein intake positively correlated with calcium excretion in each sex and age group, whereas plant protein intake increased calcium excretion in women aged 50-79 years. In conclusion, the findings suggested that the contribution of protein intake, especially animal protein, correlated greatly with calcium excretion (Itoh 451-2).

The Dr Kerstetter's study only proved that high protein diets led to the excretion of urinary calcium in healthy women. However, the experiment conducted by Dr Itoh, Nirshiyama, and Suyama not only proved that excess proteins could affect both healthy women and men. Indeed, excess consumption of protein can have influential effects on any individual regardless of age, sex, or race. MECHANISMS: Studies showed that a diet that is high in animal protein and low in fruits and vegetables comprises of mainly sulfates and phosphates. Therefore, it generates a large amount of acid. As the result, the kidneys will have a positive net of acid excretion.

Indeed, hypercalciuria is directly related to net acid excretion. Different dietary proteins differ greatly in their potential renal acid load (PRAL), and therefore in their acidogenic effect (Barzel 1051-52). If a diet is high in acid-ash protein, it will cause excessive calcium loss due to its acidogenic content. An acid-ash diet is a diet that creates acid in the process of its metabolism.

Some examples of foods that have high PRAL are fish, meats, and many grain products. In contrast, milk and non-cheese dairy products have low PRAL. Fruits and vegetables have a negative PRAL, which means that they supply alkali-ash. Indeed, consumptions of fruits and vegetables will oppose the hypercalciuria effects caused by high protein diets. To give a visual demonstration, the following table will give the PRAL values for some of the food groups (Barzel 1053). In the table below, some values of the meat products that contain high amounts of proteins show high PRAL values whereas foods with lower protein show lower PRAL values and vegetables show negative PRAL.

For examples, cheese with higher protein content contains 23.6 mEG/100 g, fish have 7.9 mEG/100 g, and fruits and vegetables have -3.1 mEG/100 g and -2.8 mEG/100 g. In response to the increase in the acid content caused by high protein intake, the body will use bicarbonate in the blood to raise the blood pH to the normal level. However, if the stress is prolonged, the body will use the skeleton to excrete buffers in order to alkalize the acidosis. Bone, the major component of the skeleton system, is a very large ion exchange buffer system. Reports show that bone contains 80% of total body carbonate in its hydration shell, and 80% citrate and 35% of 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 resorted 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 HYPERCALCIURIA 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..