Question 2
In the article, Are High-Protein, Vegetable-Based Diets Safe for Kidney Function? A Review of the Literature, what are some possible reasons that there are numerous conflicting conclusions seen in the studies reviewed.
Conclusions
This was a great discussion about how to sort through conflicting evidence cited in many articles about one main topic. Posts were very insightful as to why there were so many different results and conclusions in the studies reviewed. First and foremost, the studies may all have procedural differences. No two studies are alike; even when the exact same study is repeated, results may vary. Other differences in the studies include: length of the study, range of protein intakes, source of protein intakes, specificity of type of protein (animal vs plant, or breaking these down into subgroups of what protein foods were consumed), whether or not the patient was on dialysis, and larger sampling sizes may have been needed for some of the studies. In addition, it was noted that as far as transferring research information into clinical practice, every client is unique and has individual circumstances, and information from these studies may or may not be helpful in treating each particular patient.
posted by Andrea @ 12:40 PM
46 comments
46 Comments:
Many conflicting conclusions in the studies were due to procedural differences between studies, such as length of study, range of protein intake by subjects, and mixtures of protein source (A, V, A-V, in addition to specific types of protein within each of those categories). For example, one study did not identify specific types of protein used in other than describing it as “animal protein” (which affects extent of conclusions drawn from the study since other studies found differences in GFR between various types of animal protein)and another study transitioned patients from a mixed A-V diet to a purely vegetarian diet but results were inconclusive because total protein intake was decreased as well. Conflicting results combined with lack of very defined procedural techniques or use of different subjects (diabetic/nondiabetic or CKD vs. normal kidney function) make it difficult to apply results to all CKD patients.
I agree entirely with Vanessa. All of the studies had differing variables and no definite conclusion can be identified or applied to each pt. Plus, the study on CKD pts did not identify if all the pts were on dialysis or not.
There are a variety of reasons why there are conflicting conclusions seen in the studies reviewed. Not all patients are the same; everyone’s body is different, some people might actually need more nutrients than others, some might have other problems than CKD, or even different reactions. It is important to diagnose based on the individuals needs. The exact diet of the patients could have been different, different proteins or amounts of proteins could have been used. Maybe not enough people were studied. There are a variety of thing that could have made these studies have different outcomes. With this researchers can take this information and maybe conduct further studies on this topic.
Vanessa, I agree with you that conflicting results combined with lack of very defined procedural techniques or use of different subjects make it difficult to apply results to all CKD patients. Everything in research should be exact and well defined. The research should have had the same subjects with the same exact problems. If it is not it is hard for us to compare studies and gain valid information when there are conflicts. More studies need to be done on this topic.
Vanessa did a good job of explaining why the results may be different. The various studies had different subjects, types of protein, amounts of protein intake, and lengths of study. Since they were not all looking at exactly the same situation then naturally the results will be different. I think also a lack of quality subjects in the area makes it hard to create a well designed study. Many of these studies used rats as subjects due to limited availability of humans. This is obviously not ideal. I also think that the amount of protein given is interesting. It seemed that many of these studies had intakes of 1.0-1.5g/kg/day which is greater than the standard .8g. Is that so they can see greater effects? Or is it because they assume most people consume that much anyway?
I agree that the differing procedures of the studies make it difficult to apply the conclusion to all renal patients. Further, the article explains the fact that CKD patients are often protein malnourished, but at the same time, too much protein can cause adverse effects on the patient's body. Therefore, it would be difficult as a dietitian to find that proper balance of grams of protein that would be optimal for a particular patient. We might calculate needs based on our observations, and then after the patient complies with this, we find out that we need to lower protein intake for the individual. Also, the studies included both vegetable and animal protein intake, so the conclusions may be skewed because of this.
There have been conflicting conclusions about protein and CKD because not one study is the same. There have been multiple studies that have differed in length, variables, and many other things that will cause differing results. To be able to get a unanimous decision, one would have to perform the same study over and over, but to make sure a study shows something with substance, the conclusion should remain the same no matter what type of study is done with any type of CKD patient. –Pam Moore (I am having trouble logging in)
I think there are numerous conflicting conclusions within the article because not all treatment works for everyone. There are most likely statistics that illustrate the benefits experienced by a low protein diet as well as a standard protein diet. Patients will do what works for themselves as an individual and it’s possible that a low protein diet did not decrease the prevalence of symptoms in some cases.
Pam,
I agree. The study would have to be consistent to have a reliable conclusion. And even if the same study was performed without modifying the variables, there are still possibilities of variation that could cause contradiction.
The main reason for the differences in results between the studies is due to differing research methodologies. The studies varied in the subjects, types and amounts of protein administered, and the overall length of the studies. These types of variations can account for large differences in the overall outcomes. I think the point that Annie brought up was very interesting and the articles did very little to explain the reasoning for varying levels of protein administered during each study. So why did they provide 1.0-1.5 g/KG of protein when the RDA is only .8g/KG?? Administering higher amounts of protein would likely produce exaggerated metabolic responses, and it has also been shown that most Americans do consume well above the RDA levels for protein. So…either one of those, or a combination there in, could possibly be the reason for the higher protein levels given during the studies.
One very significant reason for the conflicting data could be that the kidney is so stressed and damaged that it can no longer metabolize these proteins as they would be metabolized in a healthy individual. The author of the article states, “It may be that fibrosis and scarring often present in a diseased kidney do not permit the hemodynamic changes and remodeling that take place in a healthy kidney.” If the kidneys are metabolizing all proteins in an altered manner, one could expect to see altered results as oppose to those intended, differentiating results.
The conflicting results of this study could be due to many reasons. To being with, each patient that participated in the study may not have had the exact same background. Previous health complications, food tolerances and medications may have played a role in the different results. Another thought is that patients that are following a vegetable based protein diet may be experiencing malnutrition due to nitrogen excretion. Certain individuals may not be accustomed to following a high fiber diet and a rapid increase may cause a hurried bowel movement. Therefore, they may not be fully absorbing all of the essential amino acids that are found in complete proteins and therefore experiencing malnutrition.
I feel a significant reason for several conflicting conclusions seen in the studies is due to people being very individualized. Recommendations will be different for each patient. One patient may have CKD along with other complications different from another patient with CKD. Patients can be in different stages of CKD, have different tolerances, and may be on medications that can effect the results. A low protein diet may work for one patient whereas a standard one may work for others.
There are many conflicting conclusions between studies due to many factors. First of all, each study is different, not exactly the same. Therefore they can not all make one conclusion. Different amounts of protein, lengths of time, and varying subjects all make these studies quite different. Also, each person with CKD may respond differently to the varying amounts of protein. These people were not all similar in the severity of CKD or other factors. To make these claims, multiple studies need to be conducted that are the same.
Vanessa,
I think you make a good point in explaining why the reults may be different. Having procedural differences between studies is not going to show accurate results for all CKD patients. Also using subjects with different complications (diabetic/nondiabetic or CKD vs. normal kidney function) will make it difficult to apply the results to all CKD patients. They should think about using the same subjects with very similar complications for each study.
There are several reasons that the studies provide different results. Each patient is different and may be at different stages of CKD. The studies also used different kinds of animal proteins, which may affect people differently. The procedures also vary, which tends to cause variance in results. The patients may also be experience other complications such as anemia and cardiovascular changes. These differences are why it is important to do research in order to demonstrate consistent results.
There could be many possible explanations for the conflicting conclusions. The one that sticks out the most to me is that every patient and case is different. We learn everyday in class that there is always a "grey" area. Some patients may have multiple problems and of course age, sex, and a variety of other factors will cause conflicting data. The degree of their CKD may be different and some may be nutrtionally managing it well and some may not.
I don't think any two studies will show the same results because of human error, variables, and the different ways the studies are carried out. Also while some studies may be very specific, as Vanessa pointed out, others may generalize variables. Also, there will be studies that show benefits for both low protein diets, and standard protein diets. I think it could depend on the individual, but I don't think any of the studies should be considered conclusive yet.
Nicholas-
I agree. It is possible that the kidneys are so stressed that while metabolizing proteins in an altered state it is producing altered results.
Vanessa explained the differences in the studies the best. The different conclusions stem from the differences in the procedures and controls during testing. When conducting research such as this it is important to keep the controls as close as possible in order to identify the difference or similarities in the study. In these studies, there are too many factors that affected the research to reach a conclusion. When conducting a study such as this it would be best to use the same subjects, same grams of protein (animal vs. vegetable), and keep the rest of the diet as close as possible.
Vanessa explained the logistical reasons why the studies are creating conflicting results very well. If studies are not done in the same fashion then the results will not be comparable due to variable differences. Many people have commented that this is a flaw and no valuable information can come from this. I agree with this comment to an extent but I also think that it is necessary to look at problems from every angle possible. By designing experiments differently to test the same general problem, you may find flaws that wouldn't have been found in the other studies done. If these flaws were not found this could be detrimental if this treatment was put into practice and eventually did harm to our patients.
I really liked Samantha McCoy's comment relating to individual difference. Each individual will react differently to the treatment even if the variables are held constant. This may provide you with enough information to come up with generalized conclusions, but this does not guarantee that this one treatment is the best for every individual you will see.
Jamie said...
There is always conflicting conclusions when compaing studies. In this case with CKD, the kidneys are in constant distress, which may make it very difficult to determine the needs of the body.
Vanessa explained very well the reason for differences in the studies. If the studies use different subjects, protein intakes or lengths of the study, those are all areas that can cause the studies to conflict. I agree with Annie about the use of rats in some instances instead of human subjects. It doesn’t give conclusive evidence if they are not using human subjects in my opinion. These studies also used an increased amount of protein grams per kg. It doesn’t really state a reason for this either.
Karlie and Annie,
You both did a great job of questioning the protein intake amounts in the study. This study never really gives a reason as to why those amounts are above 0.8g/kg. It puzzles me as to why they would make the participants in the study consume more. As Karlie said, most Americans are consume much over the RDA amount.
It is very difficult to compare clinical studies on this topic because each study is done a little differently and tracks differnt things. For instance type of protein, vegetable or meat, and what they consider to be "meat". As others have mentioned whether someone was on dialysis or not is a huge consideration, their lab values will be very different.
As mentioned there are too many variables that differ from one study to another, making it hard to form conclusions. It would be interesting to see the results from studies that where a longer time period and had comparable varibles.
Seems to me most people are in agreement that each case study of CKD is different because every person is different, each person with CKD will act differently to the amount of protein given to them and the type of protein. Further research is needed to see if a common thread of information can be found to link all of the studies together.
well one reason there might be conflicting differences is that the kidney gets so stressed it can't metabolize the proeins. And if their was anything in their past history that doctors don't know about it could make the condition worse. And some patients that are following a vegetable based protein diet may be experiencing malnutrition due to nitrogen excretion. Thats why I think there should be some if even alitte of animal protein inculded in the diet.
Samantha,
Good point. Not all pt are the same. Some might absorb more some less. They also could have a prexisting condition that might have them absorb more. Thats something to think about.
Wouldn't life be grand if studies were simple to compare against eachother... oranges against oranges, apples against apples? Unfortunately that wish is difficult to grant due to different variables in different studies. Good thing if you are a member of ADA ;-) you get the opportunity to read the published review of literatures to then make your own conclusions.
There are many reasons for conflicting conclusions: different procedures, different protein intakes (including amount and source), subject’s condition, length of study. All the subjects are different thus the effect of protein may be different for everyone and their current condition. You can’t really generalize results as it seems to be that individualization and condition status are more important in determining needs and whether or not a restriction would be helpful.
There are several reasons that there are conflicting conclusions seen in the studies reviewed. One reason is that not all patients are at the same stage in CKD. This also leads to people having different symptoms and because each individual is different they probably react differently to the treatments. People need to realize that there is not one magic cure for everyone, just because something might help one individual that does not mean that it with help others. Each individual should have diets and treatments set up that specifically will meet their needs.
I agree with everyone that has said the studies were very different and that is why the conclusions have been variable. But this is why I think there should be more structured, reliable data for or against protein restriction. I think that yes to some degree patient variability does exist but I also think if there were similar, repeated, controlled studies on protein restriction and the results were still this inconclusive then I think that those results would really target whether or not protein restriction should be recommended.
Vanessa,
I agree with you that if we are to get consistent results regarding appropriate protein intake for CKD patients, we need more consistent, replicable experiments as opposed to these very variable-latent experiments cited in this article. Procedures for these CKD related studies must be more consistent if we hope to ever see consistent results that can be directly attributed to an independent variable (i.e. protein intake).
Jamie said…
Jodee – I agree to the fact that patients are not at the same stage of CKD as others; therefore, this can lead to conflicting conclusions (such as you stated). Protein requirements are going to be different for each patient at each stage of his/her disease. This makes it difficult to gauge the correct protein allotment.
There are many possible reasons for numerous conflicting conclusions seen in the studies reviewed. I agree with what others have said as far as the variables in these studies. As with all studies, the patients used are different with varying needs, possible varying degrees of CKD, and undoubtedly react differently to certain treatments. The studies varied in length of time and procedures used. Also, the different types of protein may have had different effects of the individual patients.
Breine, I definitely think that your analogy of comparing oranges and apples helps to explain exactly how complex research studies can be. Sometimes two studies can be related to the same subject, but their methodology is set up so differently that you really can’t generalize them into one group. And, if they are that different, should we really be comparing the findings? I completely agree that organizations, such as the ADA, help professionals in their fields interpret studies, which then allows the individuals to evaluate the findings and come up with their own conclusions.
I completely agree with Vanessa that the main reasons that there might be conflicting conclusions is because of the differences between the reasearch designs. These differences, such as protein sources, length of time the experiments were performed, and the amount of protein give to the subjects, do not give exact procedures, which therefore will more than likely not yield the same measurements for CKD clients. Also, I agree with Annie and Karlie that if they are already giving the clients high amounts of protein sources as compared to the RDA, than the process of protein metabolism rates tested and the lab tests performed will return higher results.
The conflicting conclusions could be the result of each pt reacting differently to the treatments. The pt’s previous conditions will effect what is happening in the current study; pts are in different CRF stages, different amounts of pro, calories, and nutritional status. These will affect the study and cause conflicting results. It is helpful to read the studies, learn what we can from them, and go from there. This is the only way we will eventually have significant results that will be able to apply to a variety of stages of CRF pt.
There are a variety of reasons why there are conflicting conclusions seen in the studies reviewed. Everyone’s body reacts to nutrients and food differently so it is important to find out what diet works best for that client. No two clients can be treated the same therefore the study has conflicting conclusions because there is no set instructions to follow. Each person consumes and metabolizes protein, calories, fat, fluid and so on at a different rate therefore it is important to get to know your patient and their individual needs when working with them.
The variability of the subjects, types of protein given, and the amounts of protein given are all possible reasons that there are conflicting conclusions between studies. One major factor are the subjects, no matter how hard you try to get similar subjects the outcome may be different due to physiological differences between the subjects.
Nicholas Schwab… I agree with you. Due to the diseased state of the kidneys in the patients the results could be altered. It would be hard to predict exactly how the kidneys will metabolize the proteins in each case.
I agree with the reasons that have been give for the conflicting conclusions in the studies. Vanessa, you made some good points, there were a lot of procedural differences between the studies which would lead to conflicing results. Nisa, also made a good poin that the patients who were on dialysis were not identified. This is why it is important to think critically when reading a research article. You really have to dig deep into what the researcher is doing and look for possible coufounders. This is not always easy to do, but it becomes easier with the more research that you read.
Vanessa,
I agree that there are many reasons for these conflicting conclusions. The length of the study, the range of protein intakes, and every person is different. No two studies will ever be the exact same because subjects will differ in opinion. (pam moore)
Lori-
I think you bring up a good point about “grey” area. As we discussed in class not everyone reacts the same way to something. That is why treatment plans need to be individualized to ensure that a specific patient is getting what they need to become better. That is why it is likely that the outcome of the studies were different because the patients had different treatment plans and they reacted differently to the treatments.
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