Effectiveness of dietary supplements
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Cholesterol-Lowering Dietary Supplements: Effectiveness and Mechanisms
Several dietary supplements have been shown to significantly reduce plasma total and LDL cholesterol levels, especially in people with high cholesterol. Supplements such as phytosterols, berberine, viscous soluble fibers, garlic, soy protein, certain probiotics, and polyphenol extracts can lower LDL cholesterol by 3–25%. These supplements work through different mechanisms, including increasing bile acid excretion, blocking cholesterol absorption in the gut, boosting liver LDL receptor activity, and reducing cholesterol synthesis in the body. Their cholesterol-lowering effects are generally stronger in people with high cholesterol compared to those with normal levels .
Dietary Supplements for Sleep Quality Improvement
Amino acids, melatonin, and vitamin D supplements have been found to significantly improve subjective sleep quality. While the benefits of magnesium, zinc, resveratrol, and nitrate are still being studied, current evidence supports the use of amino acids, vitamin D, and melatonin for better sleep. However, the results for vitamin D and melatonin show high variability, indicating that more research is needed to confirm their effectiveness .
Impact of Dietary Supplements on Sepsis Outcomes
In adults with sepsis or septic shock, most dietary supplements do not significantly reduce mortality. However, magnesium and vitamin C have shown some benefit in lowering 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 been shown to shorten overall hospital stays .
Plant-Based Supplements for Menopausal Symptoms
Plant-derived dietary supplements, including those from soy and red clover, can significantly reduce menopausal symptoms such as hot flashes. Most studies report improvements in symptom scores compared to placebo. However, the quality of evidence varies, and more rigorous research is needed to confirm these benefits and understand their long-term effects .
Dietary Supplements in Inflammatory Bowel Disease (IBD)
Animal studies suggest that polyunsaturated fatty acids, flavones, prebiotics, and probiotics can help reduce inflammation and oxidative stress in IBD, protect the gut barrier, and alter gut microbiota. While these findings are promising, more rigorous and translational research is needed to confirm their effectiveness in humans .
Nutritional Supplements in Depression Treatment
Omega-3 polyunsaturated fatty acids (n-3 PUFAs) and zinc, when used alongside antidepressants, have shown some effectiveness in improving depression symptoms. Folic acid did not show clear benefits, and evidence for other supplements like inositol, vitamin D, vitamin B12, and SAMe is limited or mixed. Overall, more high-quality studies are needed to draw firm conclusions about most supplements for depression .
Oral Nutritional Supplements for Malnourished Elderly
In malnourished care home residents, oral nutritional supplements (ONS) are more effective than dietary advice alone in improving quality of life and increasing energy, protein, and micronutrient intake. ONS led to higher quality of life scores and greater nutritional improvements after 12 weeks compared to dietary advice .
Complementary Food Supplements for Childhood Anaemia
In young children from poor rural areas, complementary food supplements combined with dietary counseling significantly reduced anaemia prevalence and improved feeding practices. However, there was no significant effect on stunting rates over the study period. These interventions are especially beneficial in areas with high anaemia rates .
Cognitive Performance and Dietary Supplements
For healthy young adults, especially in military settings, tyrosine and caffeine may help enhance cognitive performance during sleep deprivation. Caffeine can also improve vigilance and attention during prolonged operations. However, evidence for other supplements is inconsistent, and most studies in this area are of low quality .
Consumer Perceptions of Supplement Effectiveness
Consumers often believe that multi-ingredient supplements at low doses are more effective than single-ingredient ones, likely due to a “more is better” mindset. At higher doses, the perceived difference between multi- and single-ingredient supplements disappears. These perceptions may not reflect actual efficacy and highlight the need for better consumer education and regulation .
Conclusion
Dietary supplements can be effective for specific health outcomes, such as lowering cholesterol, improving sleep quality, reducing menopausal symptoms, and addressing malnutrition or anaemia in targeted populations. Some supplements also show promise in supporting mental health and cognitive performance. However, the quality of evidence varies, and more rigorous research is needed for many supplements. Consumer perceptions of supplement effectiveness do not always match scientific evidence, underscoring the importance of informed decision-making.
Sources and full results
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.
Efficacy of Dietary Supplementation in the Relief of Inflammatory Bowel Disease: A Systematic Review of Animal Studies.
Dietary supplements, such as polyunsaturated fatty acids, flavones, prebiotics, and probiotics, show potential in reducing inflammation and oxidative stress in inflammatory bowel disease.
Efficacy of adding nutritional supplements in unipolar depression: A systematic review and meta-analysis.
Adding nutritional supplements to antidepressants may be effective for treating unipolar depression, but more data is needed for most substances.
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