Dietary supplements efficacy
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Cholesterol-Lowering Dietary Supplements: Efficacy and Mechanisms
Several dietary supplements have shown significant efficacy in lowering plasma cholesterol, particularly total and LDL cholesterol, in individuals with high cholesterol. Supplements such as phytosterols, berberine, viscous soluble fibers, garlic, soy protein, specific probiotics, and certain polyphenol extracts can reduce LDL cholesterol by 3–25%, depending on the supplement and patient profile. These effects are more pronounced in people with high cholesterol compared to those with normal levels. The mechanisms include enhancing bile acid excretion, inhibiting intestinal cholesterol absorption, increasing liver LDL receptor expression, suppressing cholesterol synthesis enzymes, and activating specific metabolic pathways like AMPK signaling.
Dietary Supplements for Sleep Quality Improvement
Amino acids, melatonin, and vitamin D supplements have demonstrated significant benefits in improving subjective sleep quality. Meta-analyses of randomized controlled trials show that these supplements can lead to measurable improvements in sleep indices. However, the evidence for vitamin D and melatonin is marked by high variability between studies. Other supplements such as magnesium, zinc, resveratrol, and nitrate may also help, but more research is needed to confirm their effects.
Dietary Supplements in Sepsis and Critical Illness
In adults with sepsis or septic shock, most dietary supplements do not significantly reduce mortality. However, magnesium and vitamin C supplementation have been associated with lower short-term mortality, though the certainty of this evidence is low. Some combinations, like eicosapentaenoic acid (EPA), gamma-linolenic acid (GLA), and antioxidants, as well as magnesium, vitamin D, and vitamin C, may help reduce the duration of mechanical ventilation and ICU stays, but no supplement has shown benefit in reducing overall hospital stay.
Dietary Supplements and Prevention of Major Diseases
Large-scale analyses indicate that most dietary supplements do not significantly reduce the risk of all-cause mortality, cardiovascular disease (CVD), or cancer in the general population. Notable exceptions include vitamin E, which may lower cardiovascular mortality, and folic acid, which may reduce CVD risk. Conversely, vitamin A supplementation has been linked to an increased risk of cancer, and β-carotene may increase all-cause mortality when used alone. The overall evidence does not support widespread use of dietary supplements for primary prevention of major diseases.
Safety and Regulation of Dietary Supplements
Dietary supplements are widely used, with vitamins and minerals being the most popular. Adverse events are rare and usually minor, with most serious issues linked to adulterated or tainted products, especially those marketed for sexual enhancement, weight loss, or bodybuilding. Regulatory oversight in the United States involves multiple agencies, but improvements are needed to better protect consumers from unsafe or mislabeled products.
Efficacy in Specific Conditions: Inflammatory Bowel Disease and Autism Spectrum Disorder
Animal studies suggest that polyunsaturated fatty acids, flavones, prebiotics, and probiotics may help reduce inflammation and oxidative stress in inflammatory bowel disease (IBD), but more rigorous research is needed before these findings can be applied to humans. In autism spectrum disorder (ASD), some specific dietary supplements, including omega-3 and certain vitamins, may improve certain symptoms, but the effects are small and not all interventions are effective across all domains.
Liver Fat Reduction and Supplement Form Perceptions
Evidence for dietary supplements reducing liver fat is limited. Meta-analyses do not support the use of omega-3 or resveratrol for this purpose, though some individual studies suggest catechins, certain probiotics, and carnitine may help. Overall, the quality of evidence is low and more research is needed. Additionally, consumer perceptions of supplement efficacy are influenced by supplement form and dosage, with multi-ingredient, lower-dose supplements often perceived as more effective, regardless of actual clinical evidence.
Conclusion
The efficacy of dietary supplements varies widely depending on the supplement, health condition, and population. Some supplements show promise for specific outcomes, such as cholesterol reduction, sleep quality improvement, and symptom management in certain diseases. However, for most major health outcomes, the evidence does not support widespread use of dietary supplements for disease prevention or treatment. Safety is generally high, but regulatory improvements are needed to address risks from adulterated products. More high-quality research is necessary to clarify the benefits and risks of dietary supplements in various health contexts.
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Most relevant research papers on this topic
Efficacy of dietary supplements on improving sleep quality: a systematic review and meta-analysis
Amino acids, vitamin D, and melatonin supplements significantly improve sleep quality, while further research is needed on magnesium, zinc, resveratrol, and nitrate supplementation.
Efficacy of dietary supplements on mortality and clinical outcomes in adults with sepsis and septic shock: A systematic review and network meta-analysis.
In adults with sepsis, magnesium and vitamin C may lower short-term mortality, but further high-quality studies are needed to confirm their effectiveness.
An overview of herb and dietary supplement efficacy, safety and government regulations in the United States with suggested improvements. Part 1 of 5 series.
Dietary supplements are popular in the US, but their safety and efficacy are often questionable, with potential risks from drugs and unsubmitted new ingredients.
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