Castro-Gonzales, I., Miranda-Becerra, D., & Montano-Benavides, S. (2009) Evaluation of Phosphorous, Protein, and n-3 Fatty-Acid Content in 15 Marine Fish Species Identifies the Species Most beneficial to Renal Patients. National Kidney Foundation Inc
The research study presented in the article aims at identifying the marine fish species that were most beneficial to patients with renal disorders. A total of 15 marine fish were samples. Evaluation of protein (P), phosphorous (P) and n-3 fatty-acid (n-3 PUFA) content helped in identification of the species. The quality of lives and rates of survival of renal patients may be determined by nutritional support in the course of treatment (Kopple & Massry, 2004). There are different types of renal diseases, which imply that the nutritional needs will also vary depending on the degree of clinical indicators and physical condition for each patient.
It is essential to note that nutrients such as potassium, phosphorous and proteins need to be supplied in limited amounts to renal patients. Proteins are required in limited amounts because of their high biological value (HBV). Although fish contain this form of HBV protein, they also contain high levels of phosphorous as well as essential n-3 polyunsaturated fatty acids. Research studies have indicated that renal patients can benefit significantly by consuming fish and fish-oil (Castro-Gonzales, Miranda-Becerra & Montano-Benavides, 2009).
The introduction section of the research gives adequate background information concerning the importance of fish oil and fish to patients with renal disorders (Kopple, 2004). The authors have shed light on the fact that previous studies have led to findings highlighting on this importance. It is however, evident that sufficient information concerning previous research has not been provided. In most research studies, there is a separate section for literature review. Alternatively, the review of literature could be integrated with the introduction section. When this is the case, the introduction plus literature review is much longer.
By conducting a review of literature, researchers get can visualize the research study and expected findings. For research results or findings to be reliable, they should be replicable. This means that conducting multiple experiments on the same topic needs to yield the same results (Descombe, 2010). Therefore, the lack of exhaustive literature review on the current study presented in the article might negatively affect the accuracy and reliability of the findings.
The findings attained from the study revealed that a majority of the marine fish species analyzed fell at an interval range of 10.5 and 23.5 for milligrams of potassium per protein grams. Generally, researchers asserted that the species studies could be integrated into normal diets for patients with renal disorders. The species that were identified as unsuitable for renal patients include California Butterfly ray, common snook, small-tail shark, William’s tonguefish and red snapper (Castro-Gonzales, et al. 2009).
A key strength noted about representation of the mentioned findings is that the researchers have provided comprehensible information and explanation as to why some fish species may not be recommendable for renal patients. For example, small-tail shark is not recommendable for renal patients because it was found to contain the highest potassium level and a lower concentration of n-3 PUFA.
According to Castro-Gonzales, et al (2009), the sample composition was analyzed separately. To obtain crude, Mexican standard test methods were used. Analysis of minerals was carried out in accordance to the Association of Official Analytical Chemists techniques. A Beckman spectrophotometer was used to analyze phosphorous while a Perkin Atomic Absorption Spectrophotometer Model Analyst 800 was used to analyze calcium and potassium. Gas chromatography with flame ionization retector and solvent extraction methods were used to analyze the n-3 PUFAs.
The fact that each sample items was analyzed separately is among the key strengths of the research study. By analyzing the items separately, it becomes extremely easy to obtain information regarding variability from the average result within the sample. As mentioned earlier, there are different renal patients, and hence the need for varying nutritional needs. This has been clearly reflected in the research study since the authors concluded that the most beneficial fish species have to be selected on the basis of protein and phosphorous concentrations (Kopple, 2004)
Although different contents of the sample were analyzed separately, the authors failed to give sufficient information concerning the methodology used to analyze each items. Only the general methods have been mentioned without an explanation on the way the analytical task is carried out. The Analytical Methods Committee (AMC) published a number of recommended methods for fish and fish products analysis. According to AMC’s recommendations, determination of protein content is usually done by obtaining nitrogen measurements. This is because nitrogen is the fundamental element contained in protein, and not the protein itself. Direct approximation of protein content is a procedure that is time-consuming. One of the commonly used methods is called the Kjedahl method, which is used to estimate nitrogen content (Saify & Akhtar, 2003).
The methods used to measure the mineral content in fish are rarely of technology-oriented. Obtaining approximate mineral measurements may serve as an essential indicator of the leaching degree of fish’s soluble constituents because of contact with melting ice or water. There are also specific recommended methods used to analyze calcium and phosphorous. It is therefore clear that the research methodology presents a substantial weak point of the research study.
A good research study should give a step by step guide of different methods used to measure and analyze different elements. The research study should enable the reader to identify and clearly understand the methodology of a research. Rather than holding the general assumption that the readers would understand the analytical methods, the researchers ought to have provided complete or exhaustive information (Descombe, 2010)
Another major weakness identified in the research study is with regard to the type and number of marine fish species used. The researchers did not include other common fish species known to contain high levels of fatty acids. Examples include crevalle jack, Spanish mackerel, and king mackerel. Failing to include adequate fish species would affect the level of representativeness of the results obtained from the study. This implies that the samples used were not representative samples and could not be applied to the general population.
Additionally, only fifteen species of marine fish were used for this study. Compared to the total number of marine fish species present, this sample size is extremely small. This could negatively affect the accuracy and reliability of the research findings (Descombe, 2010). To increase the dependability and reliability level, future studies need to target a larger sample size of at least forty marine fish species.
The results obtained from the study were presented in a general manner. Some readers may find it challenging to comprehend or easily go through results presented in such a manner. An alternative way that the authors could have used to present their findings is by splitting the results into different sections. For instance, results for crude protein composition, mineral composition, phosphorous composition and potassium composition may be presented in the form of distinct sections with subheadings. The advantage of presenting results in such a way is that it allows for easy making of comparisons in various fish elements (Chukwuemeka, Ndukwe & Audu, 2008). To increase the validity and acceptability of the findings, it is essential to present a literature review indicating results obtained from similar studies conducted in the past.
In conclusion, the experiment used was reliable because the results obtained were as anticipated. At the end of the research study, it was evident that different marine species have different amounts of minerals. The amount of phosphorus, potassium, fatty acid and protein content in marine fish species also varies. The suitability of the species for renal patients was also explained, and varies depending on the content of different elements. Fish with high amounts of n-3 PUFA are recommended for renal patients (Svensson & Schmidt, 2004). In the current study, blue runner, dollarfish and sea trout had a high concentration of n-3 PUFA and tolerable amounts f phosphorous. Hence, such species were found to be beneficial to patients with renal disorders. Small-tail shark is the least recommended type of fish for such patients because of its high level of phosphorous and low level of n-3 PUFA.
Finally, there research study implies that diet plays a critical role in survival rate and quality of life in renal patients. It is recommendable to incorporate fish diets in such patients because of such diets contain high biological protein value in addition to low amounts of potassium and phosphorous. The findings of the study are not only valuable to the medical arena, but they can also be used by nutritional professionals, especially in neurology field.
References
Chukwuemeka, U., Ndukwe, G., & Audu, T. (2008) Comparison of Fatty Acids Profile
of Some Freshwater and Marine Fishes. Internet Journal of Food Safety, 10, 9-17
Descombe, M. (2010) The Good Research Guide: For Small-Scale Social Research
Projects. Berkshire, England: Open University Press
Kopple, J., & Massry, S. (2004) Kopple and Massry nutritional management of renal
disease, Philadelphia, PA: Lippincott Williams & Wilkins
Saify, Z., & Akhtar, S. (2003) A Study on the Fatty Acid Composition of Fish Liver Oil
from Two Marine Fish, Eusphyra brochii and Carcharhinus bleekeri. Turk J Chem, 27, 251-258
Svensson, E., & Schmidt, K. (2004) The effect of n-3 fatty acids on lipids and
lipoproteins in patients treated with chronic hemodialysis. American Journal of Kidney Disorders, 44, 77-83
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