February 2015 Question 1
Do you think this is conclusive enough evidence that the ratio of MUFA:PUFA has no influence on Vitamin D-3 absorption? If yes, what convinced you? If no, how could Tufts repeat the study to convince you?
posted by Unknown @ 1:05 PM
29 comments
29 Comments:
I do not think one study proves anything to be ultimately true.There are always limitations and other methods to gain more sufficient evidence. The study could be repeated and also altered with different sources of MUFA and PUFA. Tufts could change the size of the meals, person's activity before or after supplementation, monitor sun exposure, change the ratios given, or monitor different lengths of time given the supplement.
Since this study was only conducted over one-day's worth of meals, it's hard to make conclusions about MUFA and PUFA ratios and their role in Vitamin D absorption. There are many factors that would need to be considered, including the participant's typical diet before the trials began. Since the typical American diet is higher in saturated fats than MUFA and PUFA, we may not be able to understand the role of these fats on the absorption of nutrients. I would think that in order to draw conclusions about MUFAs and PUFAs, additional studies should be done over longer periods of time.
I agree with Haley that one study does not necessarily prove any one research question to be true or false, but I think that this study was well conducted and provides enough insight to make a general conclusion that the type of dietary fat has no significant impact on vitamin D absorption. I think that this was a well designed study because the study was blinded, took place during a time when participants wouldn't be getting vitamin D from the sunlight and also because the vitamin D supplements were analyzed for purity prior to being given to participants.
I also liked how the researchers used three different blood draws (after breakfast) to assess absorption as opposed to just one draw. The researchers seemed to have covered all of their bases and performed a well designed study. Haley provided some great ideas for kinks for future studies, and if somebody else ever did perform such a variation on this study those would be great variables to manipulate to see if there was a different (or the same) result.
I agree with Haley that 1 study is conclusive enough to state that there's no diffeence between the two fats. Now that Tufts knows that dietary fat does affect serum D3, then they should do more experiments and dive in deeper by changing the differnt amounts of fats or sources or fats and comparing those results.
I also agreew ith Susan that this was only over 1 day's worth of meals so to have a longer study would be more creditable in giving a conclusion on the topic. I would also look at their typical diet and what their activity levels are.
There are so many different factors even within just the fat realm that could affect the experimenters. The researchers should try to gather participants of similar demographics and lab values to really see if it holds true for that group. Even then, those are results for that particular group and may not even be able to be generalized to the public.
Tina brings up a great point. Just because results hold true in a study designed to be unbiased doesn't mean that we can use them to make recommendations to the public. I would really like to see more research on the topic, using different designs and target populations, before making any general recommendations to large groups of people.
Like Haley said, one research article doesn't prove anything, but it does just get you thinking about possible research directions for the future. For future research I think it would help to have a greater length of time and vary the sources of MUFA and PUFA as Haley mentioned. As is true with all nutrition research, there's always going to be different factors that affect the outcomes that we can't control for, which makes it really difficult to "prove" something to the point where we can confidently start recommending it to the general public.
The study certainly added to the existing literature about the relationship between fat intake and increased absorption of Vitamin D, but I do not believe that enough evidence was provided to determine whether the MUFA:PUFA ratio has an influence on Vitamin D absorption. I believe that a longer trial is necessary to observe whether the absorption of Vitamin D between the two ratios varies or remains similar over time.
In agreement with almost everyone, the single research article certainly does not show a causal relationship between the types of fats consumed and the absorption of Vitamin D. Hopefully future research is able to expand the sample size and time frame of the study to determine if the initial results are valid and reliable.
If there wasn't any longer-term follow up, it would not be conclusive enough to see the effects if a fat soluble vitamin was better absorbed with the addition of MUFA:PUFA in the diet. If the study had follow up, compared to the sunny months, and lasted more than 6 months it would provide better evidence. However, one study is not enough to be conclusive on anything.
I agree that one study is not enough to prove anything, but I agree with Arthur that the study was well designed. I feel pretty comfortable that similar research with a larger population would likely elicit similar results. Susan made a great point that the study was limited to one day.Future research might also investigate whether different sources of fat would affect the outcomes differently based on other foods in the meal.
After reading both the original and supplemental articles, I do not believe that this study is conclusive enough to say that fat intake, specifically MUFAS and PUFAS, increases the absorption of Vitamin D. While this study adds some evidence to the potential idea that fat intake may affect the absorption of Vitamin D, more research definitely needs to be done. The supplemental article mentioned that very few studies have actually been done on the topic of dietary fat intake and its effect on the absorption of Vitamin D. Other research studies and literature cited in the supplemental article also found no difference or a very small difference in the absorption of Vitamin D when compared with high-fat intake at a meal to low-fat intake at a meal. The original article even stated that D-3 serum levels rose when MUFAS and PUFAS were consumed with Vitamin D, but the D-3 plasma levels did not; therefore, making the evidence insufficient. While it makes sense that fat would aid and assist in increasing absorption due to Vitamin D being a fat soluble vitamin, there just is not enough research to recommend this practice to clients and patients. As mentioned in the comments above, I believe that this study needs to take place over several weeks. It would allow for more time to pass. The amount of MUFAS and PUFAS should also be manipulated in order to see if this affects the absorption mechanism.
I do not think this one study is conclusive enough to determine that the ratio of MUFA:PUFA has no influence on Vitamin D-3 absorption. More research needs to be done on this topic in order to support those findings. If the study was repeated with different foods, and similar results occurred, then the results may be more generalizable. Tufts could repeat the study with different food sources of MUFAs like avocado, canola oil, and nuts, and also different PUFAs like soybean oil, sunflower oil, and fatty fish like salmon and trout. Since this study only used oils, olive oil and corn oil, I would be interested to see how the varying ratios of the fatty acids in other foods would affect the results of the study.
As this is just one study spanning only one day, I do not believe that this is enough evidence to prove the ratio of MUFA's and PUFA's influence Vitamin D-3 absorption. The study was simply not long enough, nor did it include enough participants, to provide "conclusive" evidence. If Tufts repeated the study over a longer period with more subjects, I would be more inclined to believe the findings could be used to generalize the reactions of a large population.
I had the same thought as Caroline about the sources of MUFA's and PUFA's (olive and corn oil) used in the study. If Tufts was to repeat the trial, it might be beneficial to use different foods containing MUFA's and PUFA's. However, this may present problems if doses are harder to control when using, for example, salmon. But, again, this change would allow the findings to be more applicable to the general population.
Caroline,
I like how you point out that it may be a good idea try to replicate these findings using other sources of fats. That sounds like a great idea and, like you said, may make the results more generalizable to the general population. Emma, you bring up a good point about dosages being tougher to control when using other food sources like salmon, nuts, and/or avocados.
Also, from what I'm gathering based on your responses, you first years seem to be quite interested in the research side of things...why aren't any of you (besides Jenn) doing a thesis!?!?!??!?!?!?!!??! Find something that there isn't "conclusive" evidence for, draft up a proposal, and have at it. It'll come in handy for your future career, plus it looks mighty cool on a resume. COME ON NOW!
It's not conclusive enough for me. For one, it's only a single study, and the fact that it is only a one day study makes it especially unconvincing for me. I just feel like that is such a short window of time. So, a longer study would be more convincing, for a start. And also, seeing multiple studies on this same topic would make it easier to make a determination.
I like the idea that several have mentioned about experimenting with other types of fat, too. I'd be interested to know the influence of saturated fat on absorption, as well. But at least we still know that D is fat-soluble.
And how/why did the thesis get worked into this conversation?!?
While this study certainly adds to the previously completed studies regarding MUFA and PUFA having an effect on D3's absorption, I do not think that it is enough to fully draw a conclusion. With the study only being one day long, and limited background information about the 50 participants, such as current health, past diet, and other variables, it is not enough information to form a conclusion. In order to further validate the study, the researchers could incorporate more participants over a longer period of time and observe more than one meal.
In reading this research article, I do not believe that there is enough evidence to suggest that MUFA:PUFA ratio has no influence on the Vitamin D-3 absorption. In following up to this study, I would recommend a larger sample. While there were 50 healthy men and women, I think it is important to use a larger sample to test for repeatability of the study results. Another question I asked myself with this study was whether other types of fat would show differing results in the absorption. For example, how does saturated fat affect the absorption? While saturated fat isn't necessarily something we want to recommend clients, it would be interesting to note what it is about the chemistry of the saturated v. unsaturated fat that makes it facilitate Vitamin-D3 absorption.
As mentioned in the previous comments, one study is not enough evidence to conclude that the MUFA:PUFA ratio does not have an influence on the absorption of Vitamin D3. The study would need a larger sample size and a longer experimental period than just 1 day. To make the evidence more conclusive, there needs to be studies in the future that repeat the procedure, but obviously with a larger sample and longer trials. Certainly, this study is a good start that warrants further research regarding the influence of MUFA:PUFA ratios on vitamin D3 absorption. .
I do not think that this article is conclusive enough evidence to say that that ratio of MUFA:PUFA has "no" influence on Vitamin D absorption. I think a more accurate/ appropriate way to phrase what I think about this article is that this study is conclusive enough to "suggest" that MUFA:PUFA ratio "may not" have an effect on Vitamin D absorption. Like many of the other commenters have stated, this is just one article with a relatively small sample size. More research needs to be conducted before such a broad generalization (no effect on Vit D absorption) is made. To further convince me, I think it would be interesting if Tufts conducted a similar study that had a longer duration. Also, I would like to see if different combinations of the nutrient sources of Vitamin D (supplement vs food) and sources of MUFAS/PUFAS (supplement vs food) had an effect on serum levels of Vitamin D.
My main concern with this study is that it was conducted over one day. Like many of you said before one day is not a substantial amount of time to determine the effects the MUFA: PUFA ratio has on Vitamin D absorption. Long-term studies tend to be very costly and therefore I see why the researchers chose a short-term study. Although it would be ideal to conduct a long-term study, financially it might have been seen as unrealistic to the researchers (Just something to keep in mind). Based on this study alone, I am not convinced that the MUFA: PUFA ratio has an effect on Vitamin D absorption, but if more studies were able to duplicate the results found from this study I believe the credibility of this study would greatly increase.
Also, I agree with Caroline that it would be beneficial to the research to repeat the study with different foods to see if the results were the same and therefore make the results of both studies more generalizable.
It is interesting to think they are able to research such details as the type of fats that aid with the absorption of vitamin D. I agree with everyone that they cannot form comprehensive conclusions from just this study. Like Sammy said it is very difficult to prove something to the point where we can confidently recommend it to the public, but hopefully more research will be conducted that will maybe not ‘prove’ but strongly suggest the relationship between MUFA and PUFA ratio and vitamin D supplement.
It was not enough evidence to convince me that the MUFA:PUFA ratio did not matter. After completing many literature reviews studying various topics I realize how important it is to replicate studies and conduct them in slightly different ways to demonstrate how results are unique or similar. Once there are many research studies that support a certain result it has more evidence to back the argument.
I could be convinced by having another organization replicate the study and also having Tuft's conduct a similar study but with smaller doses of Vitamin D throughout the day as the study suggested.
Concerning the effects on vitamin D absorption in a single dose on a single day with respect to the meal composition, the results do appear to be somewhat convincing in reference to the MUFA:PUFA ratios. The ratios were far exaggerated from the typical American diet ratio of 2:1 MUFA:PUFA (Enos et al., 2014) to reveal any effects. The selection of corn oil to maximize the inflammatory omega-6 proportion to omega-3s in the high PUFA group was also a wise decision, as inflammation was suggested to negatively affect vitamin D status. Though the difference in ratios seem adequately exaggerated to be relatively confident in this one day, it is hard to make conclusions from just 50 subjects. It would be interesting to see if this relationship persists over time with a longitudinal study and a larger sample size.
Enos, R. T., Velázquez, K. T., McClellan, J. L., Cranford, T. L., Walla, M. D., & Murphy, E. A. (2014). Reducing the Dietary Omega-6:Omega-3 Utilizing α-Linolenic Acid; Not a Sufficient Therapy for Attenuating High-Fat-Diet-Induced Obesity Development Nor Related Detrimental Metabolic and Adipose Tissue Inflammatory Outcomes. PLoS ONE, 9(4), e94897. doi:10.1371/journal.pone.0094897
Based on the research study and its design, I do not think that there is enough conclusive evidence to definitively state that the MUFA:PUFA ratio has a significant influence on Vitamin D-3 absorption. There are too many other variables within the study that need to be examined further before this relationship can be considered.
One aspect of this research study that I would have liked to seen included within the article was a more complete nutritional composition breakdown of the meals that were provided to the participants. I feel that there is a need to further examine other characteristics of the meals that were given to the subjects before definitively claiming that there is a clear influence with regards to solely the MUFA:PUFA ratio.
I would like to see how well the researchers were able to effectively control all other nutritional aspects of the diet as well as the source of the nutrition. I feel that this is crucial to include in order to create a more compelling argument.
I like the idea to examine saturated fat as suggested by Susan. Saturated fats are considered pro-inflammatory, and, as mentioned in the article, inflammation can affect vitamin D status. Given the higher than ideal consumption of saturated fat common in the American diet, this seems to be a very applicable direction for future research.
I think the point that John makes is an interesting one. It would be nice to see what their meals consisted of and what foods the MUFAs and PUFAs were coming from. When most research studies are done with nutrition, it usually breaks down specifically the amount of specific or certain types of foods that are eaten at meals.
Amanda also makes a valid point. While we do not usually recommend saturated fat to clients, I would be curious to see what its effect is on Vitamin D absorption, especially since more and more research is coming out about saturated fat not being as bad as we think it is for us.
Many of the comments above mentioned repeating this trial with more subjects and for a longer time. However, it seems unrealistic to conduct a longitudinal study on say 100-200 subjects (still pretty small!) and control their diets as to monitor the amount of vitamin D, calcium, and MUFA:PUFA ratio they are consuming daily. It seems even more unrealistic to control/monitor every little detail of their diets for over a week, let alone a longitudinal study of perhaps a month or a year.
Considering the difficulty of replicating the research study and increasing participants and experimental time, it seems unlikely that we would be seeing convincing, conclusive research anytime soon.
Regarding Gina's comment it's interesting to compare the study's experimental procedures to the actual American diet, with the experiment very much exaggerating the ratio. That is definitely a factor that needs to be considered when looking at how applicable the study is to the average American.
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