Abstract
—Holger Cramer, PhD, Editor-in-Chief, Journal of Integrative and Complementary Medicine
Vitamin B12 Supplementation During Pregnancy for Maternal and Child Health Outcomes
Observational studies have linked low levels of vitamin B12 in pregnant women with adverse maternal and baby outcomes. Cochrane reviewers sought randomized controlled trial evidence assessing whether vitamin B12 supplementation during pregnancy could reduce the risks of these outcomes. The reviewers found five studies (984 pregnant women) comparing oral vitamin B12 supplementation with placebo or no supplementation. All studies were carried out in low- or middle-income countries, and up to half of the participants had vitamin B12 deficiency or anemia. Reviewers found that supplementation might reduce the risk of deficiency and improve blood concentrations of B12 in mothers and babies, but they were uncertain about these findings. They were also uncertain about effects of B12 supplementation on other maternal and baby outcomes, such as miscarriage or neural tube defects, because the outcomes were not reported or were reported in ways that did not allow meta-analysis. The overall conclusion was that vitamin B12 might improve B12 status in mothers and babies, but the impact on other maternal and infant health outcomes is currently unclear.
Alpha‐Lipoic Acid for Diabetic Peripheral Neuropathy
Up to half of people with diabetes are affected by diabetic peripheral neuropathy (DPN). Common symptoms of DPN include pain and tingling, and complications may include ulcers and amputations. Some studies suggest that the antioxidant alpha-lipoic acid may help treat DPN. Cochrane reviewers summarized evidence from three studies (816 adults with type 1 or type 2 diabetes and DPN) comparing at least six months of oral or intravenous alpha-lipoic acid with placebo. Reviewers concluded that alpha-lipoic acid probably has little or no effect on DPN symptoms measured on a total symptom scale and alpha-lipoic acid may also have little or no effect on DPN impairment as measured by the Neuropathy Impairment Score. There is probably little or no difference in risk of adverse events with alpha-lipoic acid and placebo. None of the studies provided information on complications or quality-of-life outcomes. The overall conclusion was that alpha-lipoic acid is probably safe but not useful for DPN symptoms.
Antioxidants for Adults with Chronic Kidney Disease
Antioxidants are thought to help prevent or treat cardiovascular disease (CVD) in people with chronic kidney disease (CKD). To assess the potential benefits and harms of antioxidant treatment for people with CKD, Cochrane reviewers sought randomized controlled trials comparing natural or drug antioxidants with placebo, usual care, or no treatment and found 95 studies (10,468 adults with CKD) testing 49 different antioxidants. Reviewers concluded that antioxidants may not reduce the risk of cardiovascular death and probably do not reduce the risk of all-cause death. Antioxidants probably reduce the risk of CVD and kidney failure, but they may not reduce the risk of coronary heart disease or cerebrovascular disease, and they probably increase the risk of heart failure and infections. For people with kidney transplants, there is probably little or no difference in graft loss or delayed graft function. Reviewers were uncertain about effects for other outcomes. The overall conclusion was that more and better studies are needed to clarify the potential benefits and harms of antioxidants for CKD.
Cranberries for Preventing Urinary Tract Infections
Cranberries contain proanthocyanidins, a substance that can help prevent adherence of bacteria to the cells lining the bladder, and they are commonly used to prevent urinary tract infections (UTIs). Cochrane reviewers summarized evidence from 50 studies (8857 people) comparing various cranberry products with placebo/no treatment, probiotics, or antibiotics. Reviewers concluded that compared with placebo or no treatment, cranberry products probably help to prevent UTIs in women with recurrent UTIs and in children. Cranberry products may also help prevent UTIs in people who are susceptible to UTIs due to interventions involving the bladder. There may not be a benefit for pregnant women, older people living in institutions, or people with neuromuscular bladder dysfunction (e.g., in multiple sclerosis) or bladder emptying problems. Studies reported few side effects. The overall conclusion was that cranberry products may prevent UTIs, and further research should focus on doses of proanthocyanidins and comparisons between cranberry products and antibiotics or probiotics.
Cranberries for Treating Urinary Tract Infections
Cranberries are not only used to prevent urinary tract infections (UTIs) but also at times used to treat current symptomatic or asymptomatic UTIs. There is some uncontrolled evidence that cranberry juice may be an effective treatment for UTIs, so Cochrane reviewers sought randomized controlled trial evidence on cranberries as a treatment for UTIs. After extensive searching, they did not find any studies. Given the lack of randomized studies on this question, the reviewers called for well-designed and conducted trials comparing cranberry products with placebo for treatment of UTIs. The reviewers suggested that outcomes should include symptom reduction, sterilization of the urine, side effects, and adherence to therapy and that the dose and duration of therapy with cranberry products should be assessed.
Vitamin D for the Treatment of Inflammatory Bowel Disease
Vitamin D deficiency is associated with more severe inflammatory bowel disease (IBD). To summarize the evidence on vitamin D as a treatment for IBD, Cochrane reviewers analyzed 22 studies (1874 people with IBD) comparing vitamin D with placebo or no treatment (13 studies) or comparing different doses of vitamin D (9 studies). The reviewers concluded that vitamin D (any dose) compared with placebo/no treatment may lead to fewer IBD relapses in people who are in remission. When they compared high‐dose vitamin D (>1000 IU/day) with lower‐dose vitamin D (400–1000 IU/day), reviewers found there may be little or no difference in Crohn’s disease relapse, but there was no information on ulcerative colitis relapse. Reviewers could not make any conclusions about the effects of vitamin D at >400 IU/day compared with vitamin D at <400 IU/day. No conclusions could be made for any comparison about clinical response in people who had current IBD, about quality of life, or about the rates of study withdrawal due to side effects. The reviewers concluded that the overall effects of vitamin D treatment for IBD are unclear.
Synbiotics, Prebiotics, and Probiotics for People with Chronic Kidney Disease
People with chronic kidney disease (CKD) often exhibit gut dysbiosis, possibly due to the effects of CKD or the treatments for CKD, and it is suggested that the presence of gut dysbiosis may, in turn, worsen CKD. Synbiotics, prebiotics, and probiotics have been put forward as treatments that may adjust the balance of gut bacteria and improve both gastrointestinal and CKD-related outcomes. Cochrane reviewers found 45 studies (2266 participants) testing prebiotics, probiotics, or synbiotics in people with CKD. No two studies tested identical products and doses. Due to methodological limitations, small sample sizes, and gaps in the evidence, the reviewers could not make firm conclusions about the use of these treatments compared with placebo, no treatment, or each other. Reported adverse events were infrequent and mild. The reviewers concluded that the effects of synbiotics, probiotics, and probiotics are currently unclear but noted that there are 26 ongoing studies that may provide better evidence when their results are available.