Folic Acid Supplementation to Prevent Neural Tube Defects: US Preventive Services Task Force Reaffirmation Recommendation Statement.

Importance: Neural tube defects are among the most common congenital malformations in the US, with an estimated 3000 pregnancies affected each year. Many of these neural tube defects are caused by low folate levels in the body. Objective: The US Preventive Services Task Force (USPSTF) commissioned a reaffirmation evidence update on the benefits and harms of folic acid supplementation. Population: Persons who are planning to or could become pregnant. Evidence Assessment: The USPSTF concludes that, for persons who are planning to or could become pregnant, there is high certainty that folic acid supplementation has a substantial net benefit to prevent neural tube defects in their offspring. Recommendation: The USPSTF recommends that all persons planning to or who could become pregnant take a daily supplement containing 0.4 to 0.8 mg (400 to 800 µg) of folic acid. (A recommendation).

Vitamin, Mineral, and Multivitamin Supplementation to Prevent Cardiovascular Disease and Cancer: US Preventive Services Task Force Recommendation Statement.

Importance: According to National Health and Nutrition Examination Survey data, 52% of surveyed US adults reported using at least 1 dietary supplement in the prior 30 days and 31% reported using a multivitamin-mineral supplement. The most commonly cited reason for using supplements is for overall health and wellness and to fill nutrient gaps in the diet. Cardiovascular disease and cancer are the 2 leading causes of death and combined account for approximately half of all deaths in the US annually. Inflammation and oxidative stress have been shown to have a role in both cardiovascular disease and cancer, and dietary supplements may have anti-inflammatory and antioxidative effects. Objective: To update its 2014 recommendation, the US Preventive Services Task Force (USPSTF) commissioned a review of the evidence on the efficacy of supplementation with single nutrients, functionally related nutrient pairs, or multivitamins for reducing the risk of cardiovascular disease, cancer, and mortality in the general adult population, as well as the harms of supplementation. Population: Community-dwelling, nonpregnant adults. Evidence Assessment: The USPSTF concludes with moderate certainty that the harms of beta carotene supplementation outweigh the benefits for the prevention of cardiovascular disease or cancer. The USPSTF also concludes with moderate certainty that there is no net benefit of supplementation with vitamin E for the prevention of cardiovascular disease or cancer. The USPSTF concludes that the evidence is insufficient to determine the balance of benefits and harms of supplementation with multivitamins for the prevention of cardiovascular disease or cancer. Evidence is lacking and the balance of benefits and harms cannot be determined. The USPSTF concludes that the evidence is insufficient to determine the balance of benefits and harms of supplementation with single or paired nutrients (other than beta carotene and vitamin E) for the prevention of cardiovascular disease or cancer. Evidence is lacking and the balance of benefits and harms cannot be determined. Recommendation: The USPSTF recommends against the use of beta carotene or vitamin E supplements for the prevention of cardiovascular disease or cancer. (D recommendation) The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the use of multivitamin supplements for the prevention of cardiovascular disease or cancer. (I statement) The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the use of single- or paired-nutrient supplements (other than beta carotene and vitamin E) for the prevention of cardiovascular disease or cancer. (I statement).

Folic Acid Supplementation for the Prevention of Neural Tube Defects: An Updated Evidence Report and Systematic Review for the US Preventive Services Task Force.

Importance: Neural tube defects are among the most common congenital anomalies in the United States. Periconceptional folic acid supplementation is a primary care-relevant preventive intervention. Objective: To review the evidence on folic acid supplementation for preventing neural tube defects to inform the US Preventive Services Task Force for an updated Recommendation Statement. Data Sources: MEDLINE, Cochrane Library, EMBASE, and trial registries through January 28, 2016, with ongoing surveillance through November 11, 2016; references; experts. Study Selection: English-language studies of folic acid supplementation in women. Excluded were poor-quality studies; studies of prepubertal girls, men, women without the potential for childbearing, and neural tube defect recurrence; and studies conducted in developing countries. Data Extraction and Synthesis: Two investigators independently reviewed abstracts, full-text articles, and risk of bias of included studies. One investigator extracted data and a second checked accuracy. Because of heterogeneity, data were not pooled. Main Outcomes and Measures: Neural tube defects, harms of treatment (twinning, respiratory outcomes). Results: A total of 24 studies (N > 58 860) were included. In 1 randomized clinical trial from Hungary initiated in 1984, incidence of neural tube defects for folic acid supplementation compared with trace element supplementation was 0% vs 0.25% (Peto odds ratio [OR], 0.13 [95% CI, 0.03-0.65]; n = 4862). Odds ratios from cohort studies recruiting participants between 1984 and 1996 demonstrated beneficial associations and ranged from 0.11 to 0.27 (n = 19 982). Three of 4 case-control studies with data from 1976 through 1998 reported ORs ranging from 0.6 to 0.7 (n > 7121). Evidence of benefit led to food fortification in the United States beginning in 1998, after which no new prospective studies have been conducted. More recent case-control studies drawing from data collected after 1998 have not demonstrated a protective association consistently with folic acid supplementation, with ORs ranging from 0.93 to 1.4 and confidence intervals spanning the null (n > 13 990). Regarding harms, 1 trial (OR, 1.40 [95% CI, 0.89-2.21]; n = 4767) and 1 cohort study (OR, 1.04 [95% CI, 0.91-1.18]; n = 2620) found no statistically significant increased risk of twinning. Three systematic reviews found no consistent evidence of increased risk of asthma (OR, 1.06 [95% CI, 0.99-1.14]; n = 14 438), wheezing, or allergy. Conclusions and Relevance: In studies conducted before the initiation of food fortification in the United States in 1998, folic acid supplementation provided protection against neural tube defects. Newer postfortification studies have not demonstrated a protective association but have the potential for misclassification and recall bias, which can attenuate the measured association of folic acid supplementation with neural tube defects.