The Role of Herbs and Probiotics in GI Wellness for Older Adults

Timothy O. Lipman, MD

Disclosures

Geriatrics and Aging. 2007;10(3):182-191. 

In This Article

Herbal Use for the GI Tract

Most herbal therapies for GI disease are directed towards functional symptoms--for example, irritable bowel syndrome (IBS) and dyspeptic symptoms--or usually self-limited illness involving diarrhea, nausea, or vomiting. Emphasizing the importance of placebo responses in functional gastrointestinal diseases, a systematic review of 45 RCTs found a placebo response rate ranging from 16-71%.[26] RCTs of herbal therapies are fraught with difficulties, consequent to the widespread variability in herbal products described previously. The CONSORT group, which attempts to improve the quality of reports of randomized trials using an evidence-based approach,[27] developed recommendations to be used when reporting RCTs of herbal interventions; this effort was funded by the Canadian Institutes of Health Research.[28]

A systematic review found placebo-controlled trials of herbal therapy in a broad range of GI conditions, including constipation, nausea and vomiting, IBS, peptic ulcer disease, and inflammatory bowel disease (IBD).[4] Many of these herbal interventions demonstrated a significantly better treatment response than did placebo. However, other analyses of herbal therapy are more circumspect.

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder, and one that is frustrating to both patients and clinicians. It is defined clinically, or functionally, with features of abdominal pain or discomfort, diarrhea and/or constipation, bloating, and flatulence. The etiology and pathophysiology of IBS is unknown, although probably multifactorial, including aspects of altered gut motility, visceral hypersensitivity, postinfectious neuromodulation, luminal factors that may irritate the small bowel and/or colon, and dysregulation of the gut-brain axis. Treatment options are limited and only moderately effective, at best. Herbal therapies are often tried for IBS.

A Cochrane systematic review of herbal medicines for the treatment of IBS found 75 RCTs involving 7,957 participants; five of these trials were published in English and the remaining 70 in Chinese; only three of these trials were considered to be high quality (these three trials are discussed below).[29] Seventy-one different herbal preparations were tested in these 75 trials, and only three herbals were tested twice or more, meaning there is a lack of verification supporting herbal intervention. The herbal intervention was compared with a true placebo in only six trials, and against "conventional" medications in the remainder. Average duration of treatment was four weeks, with a maximum of 18 weeks. In the placebo trials all of the interventions demonstrated significantly improved global symptoms; in the conventional medicine controlled trials, 22 herbals demonstrated statistically significant benefits. The authors conclude that although some herbals appear to show benefit, these findings should be interpreted with caution because of low trial quality (inadequate methodology and small sample sizes) as well as lack of confirming data.

A German RCT assessed a multiherb product (commercially available as Iberogast®).[30] In this study, there were four groups: 1) the commercial product, containing extracts of nine herbs (bitter candytuft, chamomile flower, peppermint leaves, caraway fruit, licorice root, lemon balm leaves, celandine herbs, angelica root, and milk thistle fruit); 2) a "research" herbal extract, containing the first six herbs in the commercial product; 3) a monoextract of bitter candytuft; and 4) a placebo. Using a careful definition of IBS, both of the multiherb extracts were significantly better in improving total abdominal pain scores and IBS symptom score as compared to the monoextract or placebo at four weeks. Outcomes over a longer term are unknown. The individual components of this extract as well as the entire fixed combination have been studied for their effects in vitro on isolated muscle segments. In different models the individual components of the nine-herb extract as well as the intact extract have had both spasmolytic activity as well as tonic activity in isolated gut segments under different conditions.[31] These findings support the potential clinical responses of these, or potentially other herbs, for dysmotility syndromes.

An RCT compared a "standardized" Chinese herbal formulation, an "individualized" Chinese herbal formulation (formulated to specific patients by a Chinese herbal practitioner), and a placebo in subjects with well-defined IBS.[32] Compared to the placebo, both of the Chinese herbal medicine groups had significantly improved in IBS scores and global improvement score as rated by both patients and gastroenterologists. Although there was no difference in efficacy between the standard and individualized Chinese herbals, on follow-up 14 weeks after completion of the study, only the individualized treatment group maintained improvement.

Padma Lax is a Tibetan-based proprietary product, containing 13 different herbal constituents, used in Switzerland and said to "promote regularity, soothe and stimulate digestion, and help maintain proper digestive function." A small RCT found Padma Lax to be a safe and effective treatment for constipation-predominant IBS.[33] Neither Iberogast® nor Padma Lax appear to be listed in the Canadian Natural Health Products registry.

Peppermint oil is a smooth muscle relaxant and may be used for symptoms of IBS. A systematic review evaluating peppermint for this syndrome found evidence that peppermint oil improved symptoms over placebo but concluded that methodologic problems with the analyzed studies prohibited firm conclusions.[34] A subsequently published short-term (two to four weeks) RCT also found benefit from peppermint oil over placebo in adults.[35] Because of the smooth muscle relaxant characteristics of peppermint oil, it may exacerbate gastroesophageal reflux symptoms.

Recourse to CAM modalities is widespread in individuals with IBS.[36] This would be equally true among an older adult population. Rendering any firm conclusions difficult is the high placebo response rate found in IBS clinical trials and the dearth of high-quality, low bias studies confirming findings of individual herbals.[37]

An RCT demonstrated that the nine-herb German commercial extract Iberogast® and the six-herb "research product" were equivalent to cisapride for one month treatment of "dysmotility-type" functional dyspepsia.[38] A blinded RCT comparing the same six-herb extract to placebo in a block scheme lasting up to 12 weeks found that the herbal preparation improved functional dyspeptic symptoms significantly better than did placebo.[39] Artichoke is a historical medicinal plant promoted for a variety of conditions, including cholesterol lowering, improvement in digestion, liver protection with promotion of bile flow, and suppression of free radicals. A six-week RCT comparing artichoke leaf extract with placebo in subjects with functional dyspepsia found that the verum arm significantly alleviated symptoms and improved disease-specific digestive quality of life.[40]

A systematic review, limited to RCTs, evaluated the evidence for use of herbals in non-ulcer dyspepsia.[41] Seventeen RCTs were identified: four of various monotherapies and the remainder of various combinations. Nine of the 13 combination trials involved peppermint and caraway as ingredients. A wide range of other constituents were involved. Overall, in these trials, the various herbal treatments appeared to relieve nonulcer dyspeptic symptoms without toxicity. Despite this apparent therapeutic benefit, caution in interpretation has been suggested.[42] Most of the trials involved relatively small numbers of participants and were of short duration. Methodologic quality scores were overall low. The exact symptoms of dyspepsia were not consistent across studies, with probable inclusion of individuals with reflux and IBS, and the definition of nonulcer dyspepsia was often not clear. Finally, there is the major issue of publication bias--would a "no effect" study be published?

Ginger has been used since antiquity in both Chinese and Indian traditional medicine to treat nausea and vomiting. Evidence for use of ginger from animal experiments, experimental induction of nausea in humans, and nonrandomized human studies support its potential efficacy. A systematic review focusing on RCTs found evidence that ginger might be useful for nausea and vomiting associated with postoperative states, seasickness, morning sickness, and chemotherapy-induced nausea but concluded that more rigorous evidence is still needed.[43]

Of 1,500 plant species introduced into the health food market, some 800 are touted as hepatoprotective.[44] Probably the most well-known and most commonly used traditional herb for the liver is milk thistle, or Silybum. Its active components are collectively known as silymarin. Milk thistle extracts are hepatoprotective against toxic insults in animal models. Uncontrolled studies have suggested use in acute hepatic failure from Amonita phalloides mushroom poisoning. A systematic review identified RCTs of milk thistle in alcoholic liver disease, viral hepatitis, drug-induced liver disease, and mixed etiologies.[45] Although treatment durations lasted from one week to four years, no definite benefit from milk thistle could be established.

S-adenosyl-L-methionine (SAMe) is involved with methlyation reactions and has major antioxidant functions, including hepatic protection against alcohol and its metabolite acetaldehyde.[46] Because SAMe may be depleted in liver disease, replacement may attenuate liver injury, which has been demonstrated in animal models. SAMe has been studied in Europe for cholestatic and alcoholic liver disease. A systematic review identified eight RCTs investigating the use of SAMe in alcoholic liver disease, but only one trial had a large sample size and reported adequately on mortality and liver transplantation.[47] The systematic review could not demonstrate any clinical benefit from SAMe use in alcoholic liver disease. There was no evidence, however, for toxicity in the trials studied.

Chinese herbs have been used for thousands of years to treat chronic liver disease. Worldwide, and especially in Asia, hepatitis B chronic infection and asymptomatic carriage are major health problems, with increased risks of death from cirrhosis and hepatocellular carcinoma. A systematic review assessed the efficacy and safety of Chinese medicinal herbs for treatment of asymptomatic hepatitis B virus carriers.[48] Only three randomized or quasirandomized trials of poor methodologic quality lasting for more than three months involving 307 patients could be found. An herbal compound, "Jianpi Wenshen recipe," had significant effects on clearing hepatitis B surface and e-antigen as well as seroconversion from hepatitis e-positive to hepatitis e-antibody positive. Two other herbals, Phyllanthus amarus and Astragalus membranaceus, showed no significant antiviral effects compared to placebo. Eight RCTs of less than three months duration demonstrated no antiviral benefit. No data were available on long-term clinical outcomes or quality of life.

A meta-analysis identified 27 RCTs in the Chinese literature, assessing the effectiveness of Chinese herbal medicine for hepatitis B viral clearance when used alone or in combination with interferon alfa, and found significant rates of viral clearance.[49] Because of poor methodologic qualities in the studies, the authors could not reach firm conclusions but suggested that further research was warranted.

A systematic review assessed traditional Chinese medicinal herbs for treatment of chronic hepatitis B infection.[50] Nine randomized trials were identified, involving over 900 patients, but study methodology was considered adequate in only one trial. Ten different herbs were tested in these nine trials. Three demonstrated a variety of antiviral effects, but no other significant benefits were found.

Phyllanthus is an herb grown in India and elsewhere and has traditionally been used in Ayurvedic medicine for a variety of maladies, including jaundice. Phyllanthus's phytochemical properties have been elucidated, and it has been shown to block DNA polymerase in vitro. A variety of Phyllanthus species have been used for anti-hepatitis B therapy. A systematic review identified 22 RCTs involving genus Phyllanthus's use in chronic hepatitis B infection.[51] Based upon studies of poor methodologic quality, the authors of the review of the 22 RCTs suggested that Phyllanthus may have positive antiviral and liver biochemical effects. However, a recent double-blind, placebo-controlled, clinical trial could find no antiviral or biochemical benefit from a Phyllanthus species after six months of therapy.[52]

Hepatitis C is often treated with herbal therapy. A systematic review identified 10 randomized trials involving over 500 patients, mostly with chronic hepatitis C, in which 12 different herbals were compared to placebo, interferon, or other herbs.[53] Methodologic quality was found to be adequate in four trials. With one short-term exception, in the trials comparing herbs with placebo, the herbal therapy did not demonstrate improved viral or biochemical markers. Herbal adverse events were reported in six trials.

Liv.52 is a combination product containing seven herbals, touted for its protective benefits in the liver. An RCT testing its efficacy in alcoholic liver disease found no clinical or biochemical benefit after six months of use.[54]

A recent review discussed the potential antifibrotic effects of botanicals in chronic liver disease, discussing some of the herbals mentioned above.[55]

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