Poor vision is a problem that affects many people around the world. Some of the conditions that result in poor vision include age-related macular degeneration (AMD) and cataracts. AMD affects the macula, a central part of the retina. As a result, one’s vision becomes blurry. Cataracts, on the other hand, are a clouding of eye lenses that blocks light from reaching the retina, causing an individual’s vision to become blurry (Whatham et al., 2008). Research shows that vitamin A supplementation helps to deal with vision problems. Vitamin A supplementation is a health strategy that is used to eliminate the deficiency of vitamin A in the body and its consequences. The topic of this review paper is Vitamin A supplementation and vision. The objective is to determine how vitamin A supplementation affects vision.
Vitamin A Supplementation will help vision related problems.
Data and Results
In their study, Tiruvalluru, Ananthathmakula, Ayyalasomayajula, Nappanveettil, Ayyagari and Reddy (2013) investigate vitamin A supplementation ameliorate obesity-related retinal degeneration among rats. The sample used consisted of 32 lean and 32 obese rats of the WNIN/OB strain. Each group was divided into four categories and subjected to various levels of vitam A supplementation. Data was analyzed using SPSS, and they established that body weights of the lean rats remained unchanged after treatment with vitamin A supplementation. On the other hand, the body weight of the obese rats in category 3 and 4 reduced significantly. It was also established that the level of plasma glucose in the obese groups was higher and that vitamin supplementation did not influence the level of plasma glucose. The level of plasma retinol was higher in obese groups than in the lean groups. Like in the case of plasma glucose, vitamin A supplementation did not affect the level of plasma retinol.
Gene expression was also analyzed in this study and it was established that there was increased expression of rod-specific genes in the obese groups as a result of vitamin A supplementation. However, the increased level for various genes differed depending on the dose of vitamin A administered. In terms of retinal morphology, the researchers established that, while there is limited change in retinal morphology of the lean groups, there were significant changes in retinal morphology in the obese groups.
In another study, Rotenstreich et al. (2013) examined the effect of oral treatmen with 9-cis β-carotene on the visual function of patients of Retinitis pigmentosa (RP). In the study, 34 eligible patients were selected in a cross-over, placebo-controlled, and double-masked clinical trial that ran from 1st April 2008 to 31st May 2009. The participants were assigned randomly to a 90-day regime of 4 capsules daily, each capsule containing 300 mg of placebo or 9-cis β-carotene-rich bardawi. The β-carotene comprised of equal amounts of all-trans and 9-cis isomers. Dunaliella capsules were given to 16 participants while remaining participants receive placebo. Out of the 34 participants selected, 29 completed the study. Out of the 29, 21 were men and 8 were women. The mean age was 46.7, with standard deviation of 16.9. The age of participants ranged from 21 to 74 years. Ethnically, two participants were Israel-born, 10 were from either America or Europe, and 17 were born from either Africa or Asia.
Treatment with Dunaliella resulted in significant increase in the plasma content of all-trans β-carotene, both in the placebo-first group and in the Dunaliella-first group. Al-trans β-carotene was reduced after washout. However, the baseline remained higher as compared to the initial. The researchers also established that the interocular difference in the ERG b-wave responses was not significant in 27 participants out of the 29 who completed the study. However, when they analysed the eyes of the participants separately, they established that the placebo-first group showed a higher b-wave response. On the impact of treatment on maximal dark-adapted and light-adapted ERG b-wave amplitudes, the researchers established the Dunaliella treatment resulted in significant increase in the maximal dark-adapted ERG b-wave amplitude, +7.8 μV for the left eyes and +8.9 μV for the right eyes. On the other hand, the placebo treatment led to a reduction in the ERG b-wave, with the reduction more significant in the right eyes as compared to the left ones (-3.9 μV for the left eyes and -7.9 μV for the right eyes). The treatment of dunaliella also resulted in positive change in binocular mean (+8.4 μV) and visual field areas. On the other hand, placebo treatment reduced binocular mean change (-5.9 v μV).
In their study, Akuffo et al. (2017) examined the effect of supplemental macular carotenoids and coantaxidants on visual function among individuals suffering from age-related macular degeneration. They used 121 participants whom after being subjected to the treatment, they significantly improved in terms of visual function for both primary and secondary outcome measure (P=0.013 for primary outcome measure). It was also established that there were significant rise in macular pigment over time (P˂0.005).
Lastly, in their study, Wolf-Schnurrbusch, Zinkernagel, Munk, Ebneter and Wolf (2015) examined the effect of oral lutein supplementation on macular pigment density and contrast sensitivity. In the study, 79 patients were randomly assigned to two treatment groups, with 40 participants assigned to the lutein only treatment and 39 subjected to a combination of lutein and omega treatment. Six of the participants were smokers, 23 of them ex-smokers while 50 had never smoked. All participants had AMD or drusen pigmentary abnormalities. In the first 6 months, all participants took 10 mg of lutein with omega-3 fatty acids for the group subjected to the combination treatment. The macular pigment optical density (MPOD) level at baseline was 0.54+/- 0.19 D.U for the group subjected to the Lutein treatment and 0.56 +/- 0.21 D.U. After 6 months, the MPOD level for the lutein group increased to 0.66 DU and 0.60 DU for the lutein and omega group. The change in the lutein was significant (P˂0.005). On the other hand, the change in the lutein and omega was not significant (P=0.059). The authors also established that the contrast sensitivity (CS) score increased from 1.29 to 1.69 for the lutein group but did not change for the lutein and omega group. Plasma levels of zeaxanthin and lutein showed changes in the lutein group, but remained unchanged for the lutein and omega group.
Name of authors
Type of study
Tiruvalluru, Ananthathmakula, Ayyalasomayajula, Nappanveettil, Ayyagari and Reddy
Vitamin A supplementation positively affects vision
Rotenstreich, Belkin, Sadetzki, Chetrit, Ferman-Attar, Sher and Harats
Oral treatment with 9-cis β-carotene has a positive effect on visual function
Akuffo, Beatty, Peto, Stack, Stringham, Kelly and Nolan
Randomized controlled study
Supplemental antioxidants positively affects visual function
Wolf-Schnurrbusch, Zinkernagel, Munk, M. R., Ebneter and Wolf
Randomized, open label study
Lutein treatment increases both MPOD and CS levels
The studies upheld the stated hypothesis because all of them show a positive effect of vitamin A supplementation on visual function. However, the results show that not all forms of supplementation results in positive visual function. For example, in their study Rotenstreich et al (2013) established that placebo treatment resulted in negative visual function in terms of maximal dark-adapted ERG b-wave. On the other hand, in their study, Wolf-Schnurrbusch et al (2015) established that treatment, which involves a combination of lutein and omega-3, does not have any effect on MPOD and CS levels. The negative effects of some of supplementation as well as lack of effect of other supplementations raise the question as to why this is the case. As such, there is need for more research to be carried out to determine why the placebo treatment, for instance, causes reduced ERG b-wave.
The reviewed studies provide valuable information on the role played by vitamin A supplementation and other forms of supplementation on the vision improvement. The varying types of study allow for comparison. Moroever, the fact that there is a general agreement among the studies on the role of vitamin A supplementation in vision improvement provides significant proof that vitamin A supplementation is effective in treating vision problems among people. However, the studies also had various limitations. For example, Tiruvalluru et al (2013) focused only on how vitamin A supplementation affects retinal morphology. The researchers, therefore, examined the retinal morphology of the rats and drew conclusions. While the comparison between obese and lean rats lends credence to the findings, the study does not consider other factors that may have affected the retinal morphology. For instance, the obese rats reduced weight significantly over the period. However, the researchers failed to examine the possibility that changes in the retinal morphology could have been due to changes in weight rather than the vitamin A supplementation.
The general limitation of the studies is their lack of analysis of why and how the various supplementations determine the various aspects of visual function. For instance, while Rotenstreich et al (2013) established that placebo treatment has a negative effect on maximal dark-adapted ERG b-wave, they did not explain why this is the case. Similarly, Wolf-Schnurrbusch et al (2015) failed to examine why lutein treatment improves MPOD and CS levels. The number of participants in each study was also small and less diverse. For example, Tiruvalluru et al (2013) used only 64 rats from one strain; thus it is not possible to determine whether the strain could have influenced the results. Such shortcomings are witnessed in all the other studies. Despite the limitations, the studies provide valuable knowledge on vitamin A supplementation and the role it plays in visual function. The knowledge provides a basis for more research on the subject. For example, researchers can focus on the specific details, using the knowledge in these studies as a foundation.
Akuffo, K. O., Beatty, S., Peto, T., Stack, J., Stringham, J., Kelly, D., … & Nolan, J. M. (2017). The impact of supplemental antioxidants on visual function in nonadvanced age-related macular degeneration: a head-to-head randomized clinical trial. Investigative ophthalmology & visual science, 58(12), 5347-5360.
Rotenstreich, Y., Belkin, M., Sadetzki, S., Chetrit, A., Ferman-Attar, G., Sher, I., … & Harats, D. (2013). Treatment With 9-cis β-Carotene–Rich Powder in Patients With Retinitis Pigmentosa: A Randomized Crossover Trial. JAMA ophthalmology, 131(8), 985-992.
Tiruvalluru, M., Ananthathmakula, P., Ayyalasomayajula, V., Nappanveettil, G., Ayyagari, R., & Reddy, G. B. (2013). Vitamin A supplementation ameliorates obesity-associated retinal degeneration in WNIN/Ob rats. Nutrition, 29(1), 298-304.
Whatham, A., Bartlett, H., Eperjesi, F., Blumenthal, C., Allen, J., Suttle, C., & Gaskin, K. (2008). Vitamin and mineral deficiencies in the developed world and their effect on the eye and vision. Ophthalmic and Physiological Optics, 28(1), 1-12.
Wolf-Schnurrbusch, U. E., Zinkernagel, M. S., Munk, M. R., Ebneter, A., & Wolf, S. (2015). Oral lutein supplementation enhances macular pigment density and contrast sensitivity but not in combination with polyunsaturated fatty acids. Investigative ophthalmology & visual science, 56(13), 8069-8074.
Tired of Guidelines or Lack Time to Work on Your Paper, Get Original Custom Research Paper Writing Service
Thecustomwriting.com research paper writing service has saved thousands of students from stressful college life. Writing a custom research paper may be challenging, considering it has to be plagiarism-free. And it is better not to do your project than to hand in plagiarized work or hurriedly complete it if you do not have time.
Academic integrity is so vital that you may get a suspension or an expulsion because of a copy-pasted work. Writing a custom research paper requires research and writing skills to produce original content. Here are essential things to know about getting the best and legit assignments help websites.
Perfection is vital
Every website will promise you that they produce high-quality work. However, you put your money for your end-of-semester paper only to get a pass. You must learn how to identify the best writing service before committing.
Thecustomwriting.com produces quality content at all times. Rather than a quality promise, quality assurance is what you should consider before hiring a research writer. Best writing services are reliable. You don't want to partner with a cheap research paper writing service that will deliver poorly written essays hours after the due date.
Quality writers are part of the best writing service. A company that has untrained writers will fail you. Before committing, ensure that the people who will write your paper are academicians and professionals. It would help if you had a writer who will be prompt to respond to your questions and follow instructions. Writers who do not fear to ask for clarification where they don't understand are the best for you.
Beware of Scammers Posing to Provide Custom Research Paper Writing Service
It may take time and effort to find a legit custom research paper writing service. Most of the websites claiming to offer writing service trades your paper with another student. For example, if you order your paper today to submit it next week, you may find that another student has already handed over the same document.
Your money is gone, you have no paper to submit, and the deadline is in two hours. You can only sit and cook up some stories for your lecturer. Otherwise, wait for a penalty or suspension.
Others will give you half-baked papers in the name of cheap essays. Apart from reselling your paper, some companies will offer you copy-pasted work. If you don't have tools such as Turnitin or Copyscape to check plagiarism, you may find yourself in the dean's office explaining why you copied your work from the internet word-to-word.
We offer one of the best research paper writing services in the USA and the U.K.
You won’t regret choosing Thecustomwriting.com to handle your research. Your project is an essential part of your academic work. It determines whether you will move on to the next semester or if your name will appear on the graduation list. Do not gamble your education by hiring any cheap essay writing website you find on the internet. Look for a custom research paper writing service reviews before commit.
Avoid scandals by hiring Thecustomwriting.com. Count yourself lucky if you are reading this article. You are in the right direction in finding the writing service for your paper. Though many websites could have frustrated you, Thecustomwriting.com is committed to providing you with reliable service for your paper.
Thecustomwriting.com offers quality services at affordable prices, and they deliver your work on time. They have native English writers that write your paper using the correct language.
Plagiarism Free Custom Research Paper Writing Service
Our writers understand the seriousness of writing plagiarized papers. Every institution has regulations that govern how a research project is conducted. Universities and colleges take plagiarism as gross misconduct. The best writing services are those that will deliver plagiarism-free papers.
Plagiarism involves, among others, copying a published work and delivering it to your lecturer as your own without acknowledging the sources.
Another way your work can be plagiarized is the failure to include the source of your content in a research paper. If you are using someone's thought, you need to include a reference and in-text citations to show that you are using another scholars' worker.
It's a gross mistake to write a five-page paper without a single source unless the paper's nature does not require you to rely on any sources. Here are some tips our writers use to avoid accidental plagiarism:
Cite direct quotes, statistics, and paraphrased content.
Ensure that all in-text citations are included in the biography and vice versa.
Directly quoting not more than 2% of the paper, if quoting is necessary (some papers are exempted from this rule, especially literature).
Stick to high authority, scholarly sources. Our writers will hardly paraphrase content from third party blogs and other questionable sites.
Consider Buying A Custom Research Paper from Thecustomwriting.Com
Consider hiring an expert essay writer if you are not sure about your capabilities. Referencing and citations can be challenging, especially if you try to do it for the first time. It's even harder when your lecturer asks you to use a hard referencing style. For example, Harvard requires you to include page numbers, dates, and the author's name in the text. If you have several papers with a strict deadline, you should consider hiring a custom research paper writing service to help you work on your essays.
However, ensure the website you want to hire offers legit writing service. A good website should at least charge for its services. You will find many websites willing to provide you with free services. No one is that idle to sit and write a paper for free. Sites that provide free or cheap services hooks you when you least expect.
Also, consider the price of writing a paper. Though cheap essays are of low quality, other sites may have inflated prices for their rate, making you needlessly break your bank.
Thecustomwriting.com understands the need for a fair and reasonable price for most students. We know that most students need service, but they do not have enough resources. We, therefore, offer quality service that you can afford.
Benefits of using custom research paper writing service
If this is your first time considering using a custom writing service, the first thing is to know why taking such an action is the best. Choosing Thecustomwriting.com ensures professional writers handle your paper. Letting a qualified person handle your project can boost your grade. You cannot afford to fail in the upcoming end-of-semester project. In any case, your progress to the next level will be determined by how well you perform in your essay.
Thecustomwriting.com ensures the timely delivery of your work. The good thing about legit essay writers is that they can write your essay within the shortest time possible, with one page taking up to one hour at most. It doesn't matter what time you want your work done: Thecustomwriting.com is always ready for a task.
We will give you a paper written explicitly for you. We will ensure that your paper is not delivered to someone else.
Come to think of this; if five of your classmates decide to order an essay for the same class, five writers will be assigned to work on different papers instead of paraphrasing one paper and sending it to five of you.
It's our responsibility to ensure that someone from your field handles your paper. Our company has enough writers from every discipline. We provide only a research writer qualified in your subject to handle your paper. After placing an order, the first step is to screen the question and requirement and match it with the best writer. The less qualified writer has a college diploma, and they only handle high school papers. All other writers are bachelor, masters, and PhD degree holders.
We commit to quality content. We understand that failure to deliver quality service will result in the loss of clients. Therefore, we only hire qualified writers who have an in-depth understanding of your paper. Whether you want quantitative research done using Chi-square or qualitative research, Thecustomwriting.com’s writers will comfortably handle any discipline or type of paper. Besides, we offer research paper service from college to PhD. Therefore, we cannot afford to have unqualified writers. Our researchers take every instruction keenly when writing your essay.
There is nothing to worry about placing your order. Our platform has a simple, user-friendly interface that enables you to navigate to different functionalities with ease. We offer quality custom research paper writing services; thus, you don't have to worry about getting value for your money. Besides, you can track your order's progress. Our system progressively send you email notifications regarding every stage of your orders' progress; thus, you don't even have to log in to track down your order. You will also see the progress on the dashboard when you log in. Moreover, our support team will contact you when the writer needs any clarification.
Our system is designed in such a way that it allows you to communicate with your writer directly. We understand the need to clarify things yourself to the writer. Furthermore, our support team is available 24 hours to ensure that urgent matters are communicated swiftly with the writer.
The answer is yes. We value your efforts and trust to recommend us to your friends. We will offer you a discount on your next order if a client mentions your email when placing an order.
What guarantees should customers look for?
We have a written list of what we guarantee our clients in our terms. We guarantee the quality, confidentiality, free revision, original content, and timely delivery. We also guarantee money-back if, in the unlikely event, you are not happy with the quality of the paper.
What makes a reliable writing company?
It's easy to know a reputable company. First, they are transparent about their services. They offer multiple methods of communication and have qualified writers. Most importantly, they deliver your work on time, deliver original content, and honour what they have guaranteed.
Why should customers not opt for cheap essay writing services?
Cheap essay services will only waste your time. They have foreign writers who will produce plagiarized content full of grammar errors. You will waste your precious time waiting for a paper that you can't give your lecturer.
Is buying essays online safe?
It's safe to buy your essay if you take the right precaution. Before putting your money on a strange site, explore the website to see whether you will get customer reviews. They will help you make the right decision.
How do I hire someone to write an essay for me?
These are common questions with most clients. It's effortless to get a professional writer. The first step is to identify a custom research paper writing service that is legit and sign up. After that, they will guide you on how to place your order and get a writer. Some companies will allow you to choose a writer for yourself or choose a writer for you.
What types of writing services can I order online?
Our website offers a variety of legit essay services. We provide any academic assistance, including research projects, assignments, and admission letters. Visit our website to see what each service entails.
What benefits and additional features do Thecustomwriting.com services offer?
We offer several free services to our customers. We offer free revision, a discount on your first order, and free pages such as references and cover pages. Also, we have a quality control department that ensures that all papers are of high quality before delivering them to you.
Do websites maintain your privacy? Are orders secured?
Your privacy is our top priority. You will be recognized by your I.D. assigned to you after signup instead of your name. The only person who can access your account is you or anyone else you give your password. Your payment is through a third party. Therefore, your personal information will never reach our site without your consent.
What are the pros of ordering from custom writing services?
You get quality papers. We have writers with decades of experience delivering quality papers worth the client's money and much more. We understand your power to influence our progress. Your paper will be delivered on time and written by professional writers.
Hire a professional writer
Now that you know what to look for when considering the custom research paper writing services, it's time to try us. Sign up and get a discount on your first order. You don't have to worry about quality, timely delivery, and price. We know they are essential to you.