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So you have a case, now what? First, gather your information in a clear, concise manner. A worksheet is provided here for reference. Once the information is gathered, it needs to be put together. The components of a case report can vary, again depending on whom or where you are writing for and how much time and energy you have. At the very least, a case report should contain 1) an introduction, 2) a presentation of the case, and 3) a discussion. If you are writing for the purpose of sharing academic knowledge, then it should include 1) an abstract, 2) an introduction with literature support, 3) an in-depth analysis of the case, 4) the discussion with literature documentation, and 5) a conclusion with recommendations or hypothesis generating ideas. A final and important point is that the key to writing a good case report is to be clear about the “single message” that you want to deliver. What is the priority message that you want the reader to take away? Clear description of this and development of why this is so will provide a meaningful addition to the literature and offer real benefit to your colleagues.

Components of a case report in detail

1. The abstract provides a concise synopsis of your case report to allow potential readers a quick glimpse into the content of your article. Depending on the journal, the length of an abstract may be 100 to 250 words.

2. The introduction provides the background to why the case may be of interest to the reader. Literature support on theoretical or research basis of the case may be presented here.

3. The case presentation gives the detailed description of the case (i.e. presenting symptoms, treatments and outcomes) and analysis of the findings. However, this does not mean you should go on ad nauseam on the details of the case. The goal is to provide essential information and noteworthy features that may be of interest to your reader.

4. The discussion is the most important part of the case report. This is where the significance of the case is discussed; what the outcomes are, what features are unique and interesting to the reader, and why this case is important. Supporting literature that is relevant to the case should be included here as well as ideas for generating hypotheses for future research.

5. The conclusion gives a brief summary to what you have learned from the case, any implications to clinical care and recommendations that other clinicians could learn from.

Other Considerations

A case report is the medical history of a person and the clinical/therapeutic approach used to treat the person and achieve the outcome. The bottom line is that it is about a person. Thus, as an author, it is proper etiquette for you to get consent from your patient. In fact, obtaining consent from the patient is not only good medical practice, but also mandatory for some journals. In the consent form, you can inform your patient about your intentions, the types of information being shared, and any known or potential risks/ benefits. It is your responsibility to ensure your patient’s confidentiality and anonymity. For example, if photographs are used, anonymity may not be guaranteed. In such a situation, the patient needs to be informed.

A case report is derived from the detailed reporting of events that take place within the context of treating and observing a single patient (i.e. case). The report is an in-depth longitudinal examination that is essentially qualitative in nature although it may well contain quantitative data. A case report is anecdotal in that it provides informal observations that are uncontrolled, not subject to the scientific method, and cannot be independently confirmed. Although such anecdotal evidence is not regarded as strictly scientific, it is often regarded as an invitation to more rigorous scientific study. For example, in an analysis of 47 case reports detailing side effects of drug therapy, 35 were found to be “clearly correct”. Primarily a case report is a way of communicating information to the medical world through the elucidation of unique and characteristic feature(s) of a condition, complications, and adverse effects and benefits of specific interventions. Case reports may also serve as a valuable research and educational tool. Robert Iles notes that most medical case reports consider one of five topics:

1. An unexpected association between diseases or symptoms

2. An unexpected event in the course of observing or treating a patient

3. Findings that shed new light on the possible pathogenesis of a disease or an adverse effect

4. Unique or rare features of a disease

5. Unique therapeutic approaches

Why write a case report?

The objectives for writing a case report are mainly to 1) inform/educate; 2) share new knowledge/insight; and 3) document processes and procedures. Furthermore, within the naturopathic context, case reports can serve as a method for building evidence for naturopathic healthcare practice and expanding our Materia Medica. Having well-written case reports published in a reputable medical journal adds to the credibility of the naturopathic profession. The goal of a case report is to provide information of value to the audience (i.e. interesting and relevant). Information provided in a report should contain unique features about the condition, the treatment, the outcome, and anything else pertinent to the case. A case report differs from a clinical case intake in that a case report is systematic, and includes a greater depth of detail, in-depth analysis, literature support guidelines and conclusions about the findings. Case reports can also provide findings that are hypothesis generating.

As naturopathic doctors, there will likely be a strong desire to maintain a humanistic and holistic approach to care. While called a ‘case’ report, do not lose sight that we are talking about people. After all, we do not treat cases; we treat patients with presenting symptoms. Case reports provide us with a great tool for learning. Thus, case reports should be written about cases with both positive and negative outcomes, with the emphasis being on learning. In fact, as practitioners, we know that we often learn more from the negative cases. Furthermore, by writing a case report, practitioners will likely add to their own knowledge base.

Case reports play an important role in disseminating information to the medical community. Given the wide variety of naturopathic clinical practice, case reports offer an excellent opportunity to share clinical insights from naturopathic doctors. Typically, unique and rare events or patterns are depicted regarding different aspects of a case, including: symptomatology, pathophysiology, treatment(s), and outcome, including adverse effects. In this paper we elaborate on what a case report is, why one is conducted, and provide a brief set of guidelines on how one is written. We hope to encourage clinicians to write case reports and to submit them for publication. The case report is a well-respected venue for sharing valuable knowledge and generating questions derived from practice. The production of this form of clinically relevant evidence should be actively encouraged within the naturopathic community.

The peer-reviewed medical literature contains articles that cover virtually all topics within medicine including research on therapies used by naturopathic doctors (NDs). The literature is growing at an incredible rate and there is plenty of opportunity for both dedicated researchers and clinicians to participate in this process. Complex studies such as randomized controlled trials, systematic reviews, and large observational trials can be daunting to the practitioner who has little training in research methodology and too little time. The role of the clinician in private practice is critical, however, for the introduction of important clinical information from the ground up. The strength of case reports and case series is primarily in their ability to inject new information into the medical consciousness and to generate hypotheses that can be tested in controlled studies.

Case reports provide a level of evidence that is often a starting point for further research. A classic example is the drastic teratological adverse effect of thalidomide on fetal development. A single case report opened the eyes of the medical community in the late 50s when thalidomide was being touted as an effective treatment for nausea and vomiting of pregnancy. This case report opened a floodgate of responses and the publication of further case reports that quickly led to the drug being pulled from the market (1). Ironically it is through the publication of case reports that thalidomide has been brought back into usage more recently as a treatment for certain dermatological pathologies (2).

Naturopathic medicine incorporates an incredibly wide array of modalities often combined in unique ways. The holistic, individualized and eclectic ‘nature’ of naturopathic medicine makes the case report an ideal place to showcase the benefits and also the potential adverse events that can occur within its bounds. The intent of this article is to provide an overview of a case report, the reasons for writing one, and guidelines for writing and publishing such a report. We hope that this paper offers motivation and some of the tools necessary to carry out this process. The clinician who sees patients regularly is intimately aware of what works in practice. This shared knowledge is a resource that can benefit clinicians, the profession and ultimately our patients. The case report is a well-respected medium that should be encouraged so that valuable information is not limited to a few practitioners, but can be widely disseminated amongst colleagues.

Like most colonized countries in the Western world, Australia has a history of natural medicine use that dates back to the first settlement (by the British in 1788). The Government physician on the first fleet was quick to cultivate a physick or medicinal plant garden to provide medicines for all manner of ailments experienced by the government authorities as well as the convicts who established the first settlement. Of course, the original inhabitants of the country, the aborigines, had their own unique natural healing methods that included herbal treatments, food therapy and shamanic practice. Over the first one hundred years of settlement in Australia, herbal medicine, homeopathy and traditional Chinese medicine formed the greater part of early health care for the inhabitants. “Naturopathy” as such, didn’t really become an entity until the late 1960s to early 1970s, although nature cure practitioners did exist during the early part of the 20th century. Today, naturopathic medicine is second only to chiropractic as the most popular form of natural medicine health care in Australia. It is estimated that around 64% of Australians currently use natural medicine health care, whether that is through consultations with natural medicine practitioners or self-medication. They spend over AUS$2 billion annually on natural medicine treatments. This is more than the amount spent on over-the-counter pharmaceutical drugs in Australia each year. Growth of natural medicine usage has been quite significant, increasing from around 22% in 1986 to 50% in 1995, through to more than 60% in 1998. A study conducted in 1997 suggested that there were three main reasons why Australians were turning to natural medicine health care. These were:

Unlike North America, naturopathic practitioners are not registered or licensed by State legislation. Statutory regulation exists for chiropractic and osteopathy and, in one state of Australia, for Chinese medicine. The naturopathic profession is self-regulated, meaning that professional associations monitor the practice and training of practitioners. In reality this means that anyone, regardless of their level of education or training can use the title “naturopath” and practice as a naturopathic physician. As more Australians use natural medicine treatments for the maintenance and improvement of their health (often in conjunction with prescribed or over-thecounter pharmaceutical drugs), there is an increasing level of concern by the medical profession and Government about drug interactions and safety of natural therapies. This has raised the question about the need for closer monitoring and regulation by Government, of natural medicine. Currently an enquiry is underway, in one Australian state (Victoria), into the safety of naturopathy and Western herbal Medicine, and the need for statutory legislation to regulate these practices.

H was given a protocol to follow with goals of alleviating side effects; the modalities included nutrition, hydrotherapy, supplements, and exercise. A whole foods diet was implemented for weight optimization. The diarrhea was treated with eating organic yogurt and kefir as a source of probiotics. L-glutamine powder 7 g/d was recommended for rebuilding the gut as well as treating diarrhea. Zinc gluconate 20 mg/d was added for the restoration of taste. The CIPN was treated with Neurosol at one softgel twice daily.(4) The hydrotherapy consisted of home treatments including warming socks and gloves nightly to increase peripheral circulation and Epsom salt soaking baths twice weekly. The exercise protocol was a daily walk for 20 minutes. When H presented for the 11th cycle of FOLFOX, the peripheral neuropathy had completely resolved as determined by patient interview before administration of the chemotherapy. At this point H had received a cumulative dose of oxaliplatin of approximately 850 mg/m2. The dose-limiting neurotoxicity occurs with a cumulative dose between 780 and 850 mg/m2 in oxaliplatin treatment.(3) At no point during the remaining nine cycles (cycles 12-20) did H present with complaints of CIPN. The CIPN treatment of Neurosol and home hydrotherapy was continued throughout the FOLFOX treatment and discontinued after the last cycle of FOLFOX, October 2004. (Figure 1) H had excellent partial remission and was switched to irinotecan and bevacizumab, and later cetuximab. The partial remission continued through June 2005. Unfortunately, by October 2005 the cancer was found to be progressive as evidenced by CT scan and CEA (carcinoembryonic antigen) levels rising. At this point, a second round of FOLFOX (13 cycles) was started April 2006. The oxaliplatin dose was 85 mg/m2 with a cumulative dose of approximately 1000 mg/ m2. On two of the cycles the oxaliplatin dose was reduced to 75 mg/m2 due to neutropenia, but not reduced due to neurotoxicity or CIPN. H resumed a similar protocol as for the first FOLFOX treatment, including the same diet therapy of whole foods and yogurt, and a meal of organic liver and onions 1-2 times weekly to guard against chemotherapyinduced anemia. Other therapies included Epsom salt baths, Neurosol (one softgel bid), omega-3 fish oil capsules, and one tablet of silymarin 80% bid (equal to 56mg silymarin/tab). The use of silymarin is currently in question with regards to potential interactions from hepatic metabolism of other medications the patient may be on. The specific concern is that silymarin modulates the activity of cytochrome P450 enzymes and may increase the levels of toxic medications in a patient. 5 The silymarin was prescribed for liver health due to the progressive metastatic cancer in the liver. The FOLFOX combination contains three medications, none of which are hepatically cleared,6 so the use of silymarin was not contraindicated in this patient.

Since H began naturopathic integrative care his weight stabilized and was considered healthy for his height (+/- 5 pounds) for 15 months while undergoing chemotherapy. In addition, the patient experienced a complete elimination of the CIPN. The Neurosol was discontinued after recovery from the neuropathy and this symptom had not returned as of December 2006. H has had regular bowel movements without significant constipation or diarrhea with the exception of chemotherapy days when he experienced one day of diarrhea that affected daily activities. This is a reduction from seven days of diarrhea post chemotherapy before initiating integrative medical care.

In August and September 2006, while undergoing FOLFOX treatments, H enjoyed fishing trips to British Columbia and a vacation to Puerto Vallarta. H has had enough energy to be able to exercise and take pleasure in life. After the 13th cycle of FOLFOX in October 2006, H met with the oncologist and in a review of symptoms had no fevers, unusual anorexia, weight loss, peripheral neuropathy, unusual aches or pains, anxiety, depression, or rashes. There are limitations to this case report. No validated tools were used to objectively evaluate the quality of life, ADLs, and CIPN. The data was retrieved through interview and chart notes from the physicians caring for H. In summary, during the naturopathic care that the patient received, H experienced a reduction in all major side effects from the chemotherapy, increased quality of life as evidenced by the ability to not only leave the house, but also to take vacations and engage in hobbies that were previously difficult.

First line chemotherapy regimens for colon cancer include FOLFOX (leucovorin, 5-fluorouracil, and oxaliplatin). This combination of medications, more significantly oxaliplatin, has been linked to peripheral neuropathy. For patients with previous active lifestyles, peripheral neuropathy can cause a decreased quality of life. In addition, there are many other side effects of FOLFOX including nausea, diarrhea, and weight loss. Significant peripheral neuropathy in patients undergoing FOLFOX therapy may occur spontaneously after oxaliplatin infusions are discontinued. Current literature supports the need to clinically evaluate peripheral neuropathy in patients undergoing FOLFOX chemotherapy, but few studies have shown an effective way to treat the peripheral neuropathy experienced by many patients. Standard of care for chemotherapyinduced peripheral neuropathy (CIPN) includes dose reduction and/or discontinuation of the suspected neurotoxin. Such dose-limiting effects are poor prognostic indicators and often negatively affect a patient’s long-term survival.

Patient H is a 43-year-old male diagnosed with stage IV colon cancer in December 2003. After H was diagnosed he was treated with 20 cycles of FOLFOX (December 2003-October 2004). The FOLFOX was tolerated moderately well. The oxaliplatin dose was 85 mg/ m2 throughout the 20 cycle course. In February 2004, before the fifth cycle of FOLFOX, the oncologist referred H to the Integrative Medicine clinic; the referral was due to H’s desire to continue with the chemotherapy protocol with goals including weight optimization and alleviation of side effects from the medications causing decrease in daily activities and decreased quality of life.

The Integrative Medicine clinic is staffed with an internist, naturopathic doctors, acupuncturists, massage therapists, and a nutritionist. H saw Dr. Ken Weizer, a board certified Naturopathic Doctor (ND). H presented with chief complaints of weight loss over two months totaling 10% of body weight, nausea, diarrhea, and peripheral neuropathy. On exam, chemotherapy-induced peripheral neuropathy (CIPN) presented as paresthesia in the fingertips for 2-3 days post chemotherapy before complete resolution. However, the CIPN by the ninth cycle of FOLFOX was lasting a full week after chemotherapy treatments and the paresthesia progressed to include all fingers and toes. The CIPN subsequently progressed from the tips of the fingers and toes to involving the entire digits with mild to moderate pain and was affecting the patient’s activities of daily living (ADL). The CIPN associated with oxaliplatin is cumulative and dose dependent. The CIPN was graded using a subjective pain scale and through patient interview with specifics determined regarding location, duration, and effects on ADLs. There is controversy regarding the most sensitive scale to evaluate peripheral neuropathy, and many of the scales do not take into account ADLs,3 therefore in H’s case, no objective scale was used to evaluate the neuropathy.

In general, many large epidemiological and case-control studies have resulted in data describing conflicting outcomes examining the relationship between colorectal cancer and fiber intake. A combined analysis of 13 case-control studies found relative risks of colon cancer to be 0.53 with high versus low fiber intakes. Similarly, a case-control study of 2000 cases found intakes high in fiber correlated with a low relative risk. In contrast, large epidemiological studies such as the Nurses’ Health Study(48) and the Health Professionals Study did not find any such relationships. Lupton (2000) suggests that a higher intake in fermentable fiber is more protective because it results in lower colonic pH and production of the short-chain fatty acid butyrate, a primary energy source for colon cells. The recent review from Obrador examined the evidence supporting the role of dietary fiber in the prevention of colorectal cancer. While most epidemiological and intervention studies analyzed in this review show little strength in terms of cancer prevention, meta-analyses on case control studies report reductions of up to 50% in the risk of colorectal cancer associated with higher intakes of dietary fiber. However, the evidence remains weak since case-control designs are often associated with various biases, namely recall bias and the influence of the subject’s health status on the validity of self-reporting.

Among factors contributing to the inconsistency in the data available are the source and form of fiber. While some studies have shown both soluble and insoluble sources to be protective, others state that insoluble fiber is the only form that could play a role in cancer prevention. The diet accompanying fiber intake could play an important role as well, as it is hypothesized that the type of fat consumed affects gut susceptibility to cancer. Namely, oils that induce apoptosis, such as fish oil, may be more protective. Confounding the effect of dietary fiber on colorectal cancer is the natural presence of phytochemicals in such food groups as fruits, vegetables and whole grains. In fact, polyphenols and others have shown great antioxidant, antiproliferative and apoptotic activities and could be responsible for the anti-carcinogenic effect of high-fiber foods.

Although there seems to be a significant body of evidence in favor of dietary fiber as a prevention of colorectal cancer, data from well-designed studies characterized by large sample sizes show no effect of dietary fiber on cancer development or progression. Confounding factors such as composition of meals accompanying fiber intake and antioxidant properties of fiber-rich foods have made the relationship between dietary fiber and colorectal cancer inconclusive, creating the need for further research to isolate the effect of fiber on cancer development. Moreover, it should be noted that cancer itself is a complex disease that can arise secondary to other health conditions, diet and lifestyle. Health claims pertaining to colorectal cancer prevention cannot be justified based on the current literature, however given the natural benefits of fiber containing foods, a potential health claim which states that regular consumption of fiber may decrease the risk of colon cancer could be appropriate in orienting the consumer towards healthier food choices. In conclusion, evidence shows that soluble fiber reduces the risk of cardiovascular disease, and that insoluble fiber protects against disturbances of the digestive tract. Although more extensive research is needed to confirm the beneficial role of dietary fiber in the prevention of colorectal cancer and diverticulosis, the fact remains that fiber is an important and safe component of a healthy diet and has been positively linked to lower incidences of these diseases.

Human studies have concluded that total dietary fiber given at doses ranging from 20-26 g helps to normalize and improve bowel function by decreasing the incidence of constipation in elderly populations. In these studies, ingestion of fiber-rich foods or supplements resulted in significant improvements of clinical symptoms of constipation and discontinuation of laxatives. Fiber supplementation in children with chronic constipation demonstrated that the recommended ‘age in years plus 5 g/day’ dosage of total fiber resulted in a reduction in the frequency of clinical symptoms. Similar results were observed in a crossover trial using 100 mg/kg body weight of the soluble fiber glucomannan. Constipation is also commonly faced by patients administered enteral feeding. To this end, Silk et al (2001) studied the effect of fiber supplementation of enteral formulas on bowel function. Results show a reduction in gut transit time and an increased stool wet weight as compared to fiber-free formula. Although two metaanalyses examining randomized controlled trials have shown no benefits to dietary fiber in alleviating the symptoms of constipation, the choice of a study population composed of irritable bowel syndrome patients decreases the applicability of the authors’ findings to the general population. In fact, an earlier systematic review, looking at a more heterogeneous population, argued that fiber supplementation did lead to a modest improvement in bowel movement frequency and a decrease in abdominal pain. The review outlines data from 1815 patients with chronic constipation having participated in 36 controlled trials. Although special populations, namely patients with irritable bowel syndrome and diverticulosis, were included in three studies, these populations only accounted for 45 patients of the total sample size. The beneficial effect of dietary fiber on constipation is supported by the evidence in the literature linking the intake of fiber to reduced intensity and frequency of symptoms in the general population. Therefore, health claims on the benefits of dietary fiber for constipation are well founded, especially in populations at risk where more fiber is associated with the need for less laxative medication and accompanying side effects.
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Fiber Effect on Diverticulosis Prevention
In the 1960s and 1970s, Painter and colleagues first proposed a low fiber diet as a cause of diverticular disease called “a disease of Western civilization” for its high prevalence in developed countries. A suggested mechanism for the development of diverticulosis is that low fiber intake results in greater water absorption due to slower gut transit. Thus, smaller, firmer stools are produced, leading to high intraluminal pressure which, in turn, results in excessive segmentation. However, to date no human studies exist which confirm this mechanism. Nonetheless, low fiber diets have repeatedly been correlated with the incidence of diverticulosis. In fact, epidemiological studies predicted that 60% of individuals over 60 years of age, from Westernized countries, will be diagnosed with diverticular disease, partly due to a low intake of dietary fiber.

Fiber supplementation has been examined in animal models in order to explain a possible mechanism through which fiber may act to prevent the disease. It was suggested that fiber may influence the nature of collagen cross-linking in the bowel through decreased production of short chain fatty acids by gut microflora. Although animal models have shown a positive response to high-fiber diets, to date very little evidence exists on fiber supplementation and its link to diverticulosis. Results from a prospective study involving a cohort of healthy males show a more significant inverse relationship between diverticulosis and insoluble fiber than it does for soluble fiber. While no recent randomized placebo-controlled trials have been conducted to evaluate the effect of fiber on diverticular disease, earlier human trials do not hold enough evidence qualifying dietary fiber as a treatment for diverticulosis symptoms. Although patients diagnosed with the disease are commonly prescribed a high fiber diet, there is a need for further investigation into the role of fiber in the development and/or progression of diverticulosis through placebo-controlled clinical trials. At present, consumption of a diet low in fiber is considered a main cause of diverticulosis, therefore there should be a preventative health claim on the risks of diverticulosis linked to a low-fiber intake.

A dose response effect of soluble fiber appears to exist, where an increase in the amount consumed is associated with a greater reduction in blood lipids, mainly total cholesterol and LDL cholesterol, however, no optimal dose is evident in the literature. One study examined the lipid-lowering effects of 0.4 g, 3 g, or 6 g of beta-glucan in conjunction with a Step 1 diet which consists of 50% of energy from carbohydrates, 20% from protein and 30% fat, with less than 10% contributed by saturated fat and less than 300 mg/day of cholesterol in the diet. Results of the trial showed that LDL cholesterol levels were reduced by around 4%, 10%, and 14%, respectively,20 compared to a Step 1 diet alone. Considering that 3 g of soluble fiber can be found in approximately one cup of oat cereals, it is clear that such improvements in cholesterol levels can be attained with fairly low intakes of soluble dietary fiber.

Average daily intakes of total dietary fiber in Europe and the USA lie between 15 and 20 g, while the dietary review papers recommended intakes for fiber are reported to be 38 g/day and 25 g/day for men and women, respectively, with no upper tolerable intake set to this date. Adequate intakes can be attained by consuming the recommended servings of whole grains, fruits and vegetables, making fiber supplementation unnecessary. However, it is clear that an adequate consumption of soluble fiber plays a role in reducing the risk of coronary heart disease by decreasing total and LDL cholesterol levels.

The American Heart Association’s year 2000 dietary guidelines state that there is a moderate cholesterol-lowering effect of soluble fiber over and above the effect of a diet low in saturated fat and cholesterol. As well, the US Food and Drug Administration has authorized a health claim stating that soluble fiber in certain foods such as whole oats reduces risk of coronary heart disease.
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Fiber Prevents Constipation

Insoluble dietary fiber plays an important role in promoting normal bowel movement by acting like a sponge in the distal colon, therefore increasing stool bulk. Through such action stool movement through the colon is promoted, thus reducing transit time.(27) In addition to the type of fiber, the effect of fiber on stool output is dependent on the amount of fiber present. Regular consumption of dietary fiber will help increase water content and plasticity of stools, thus promoting regularity. Since the stool holds more water as a result of fiber intake, it is important to increase fluid consumption to a recommended 2 L per day in order to further the action of fiber on stool movement.

Abstract

The bulk of the research on dietary fiber started in the 1970s when what had been considered as a fad, lacking scientific evidence, gained the interest of the scientific community as improved designs and analytical methods were used to examine the health benefits of dietary fiber. Since then, epidemiological studies and clinical trials have highlighted the potential role for dietary fiber in the prevention of cardiovascular and gastrointestinal disease. Today, nutrition societies consider dietary fiber to be an essential part of a balanced diet for disease prevention. Health authorities have now approved health claims on the benefits of moderate to high fiber intakes, based on the increasingly available scientific evidence. The purpose of this review is to identify those claims, analyze the supporting evidence behind the role of soluble and insoluble fiber as health promoters, and examine the potential for further health claims, based on recent studies in fiber research.

Methods

The literature was searched using mainly PubMed (accessed in 2006 and 2007). References cited in this review comprise peer-reviewed original research articles, reviews, metaanalyses as well as government regulation reports. The bulk of the evidence includes work published after the year 2000; although, findings published between 1960 and 1990 were also used to illustrate the early work in the field of fiber research.

Fiber Efficacy for Lowering Total and LDL Cholesterol, and Decreasing Risk of Coronary Heart Disease

Recent animal studies show a significant effect of fiber on blood lipids and suggest potential lipid-lowering mechanisms including satiety effects and moderate to low bile acid-binding capacities. In humans, there is little evidence showing a link between insoluble fiber and coronary heart disease risk factors as well as mortality. A common limitation to human studies examining the lipid-lowering effects of insoluble fiber is a lack of control on the diet and lifestyles of subjects or populations assessed. Thus, there is a contributing confounder by way of the effect of a healthy lifestyle on blood lipid levels. A review by Truswell (2002) showed that 27 of 34 human studies testing efficacy of insoluble fiber saw no reductions in plasma total cholesterol. In addition, experiments that did show significant reductions had inherent weaknesses such as short durations and one-way designs (control-test) where subjects ate ad libitum. Thus, the controversy behind the efficacy of insoluble fiber in decreasing risk factors of cardiovascular disease remains unresolved.

In contrast, there is an abundance of evidence supporting beneficial effects of soluble fiber on plasma lipid levels. At least forty human trials have indicated high efficacy of oatmeal or oat bran in reducing plasma lipids. Doses of soluble fiber ranging from 3 g to 8 g have induced significant reductions ranging from 2.0% to up to 24% in total and low-density-lipoprotein (LDL) cholesterol in both hypercholesterolemic and non-hypercholesterolemic individuals. Unlike human studies involving insoluble fiber, the clinical trials mentioned here are characterized by their strong designs, including large sample sizes and controlled study diets, reinforcing the validity of their findings. A pooled analysis of cohort studies conducted in the United States and Europe showed that incremental intakes of 10 g/day of cereal and fruit fiber intakes were associated with 25% and 30% reduction in coronary death, respectively. In addition, studies have demonstrated that higher intakes of soluble fiber may reduce the incidence of metabolic syndrome characterized by elevated LDL cholesterol levels, decreasing the risk of cardiovascular disease. Cholesterol lowering action of soluble dietary fiber was explained by Yoshida et al (2005) as a result of an increased fecal sterol excretion and/ or production of short-chain fatty acids previously shown to play a role in the suppression of cholesterol biosynthesis.