Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 418

Even in industrialized countries, the vast majority of adults consume much less than the recommended amounts of many vitamins and minerals from foods, including magnesium, calcium, and vitamins A, C, D, E, and choline, as well as iron for young children, women of childbearing age, and women who are pregnant.^7,13 A systematic review of community‐dwelling older adults identified six nutrients that may be of public health concern: vitamin D, thiamin, riboflavin, calcium, magnesium, and selenium.⁸ Use of MVM supplements markedly improves nutrient intakes and decreases the risk of inadequate intakes.¹³

While nutritional deficiencies and insufficiencies of any essential nutrients have health consequences, it is unclear whether routine supplementation of individual nutrients at or above the recommended amounts can prevent or treat chronic diseases that are not ‘deficiency’ diseases. While there is considerable interest in whether supplements of vitamins and/or minerals prevent or delay the progression of diseases, there has been insufficient research on the topic and conflicts in the evidence to date.^13,14 Longitudinal cohort studies typically examine the role of food intake patterns and/or dietary and supplemental sources of nutrients and chronic diseases. In these studies, it is often difficult to fully disentangle the effects of the supplements from other health‐seeking behaviours.¹⁴ Much of the information presented here is from randomized controlled trials (RCTs) in which participants are randomly assigned to one of several interventions with dietary supplements or a control group (placebo or no intervention). Across RCTs, there is variability in criteria used for disease outcomes and the amount and chemical form of the nutrient(s) in the supplements (see examples in Table 16.3). Thus, further research will continue to be needed to address these and other issues.

When available, this section emphasizes evidence from authoritative reviews and recommendations regarding the role of micronutrient supplements. The information comes from the US Preventive Services Task Force (USPSTF), Cochrane Reviews, meta‐analyses, and practice guidelines based on the best available information. Created in 1984, the US Preventive Services Task Force is an independent, volunteer panel of national experts in prevention and evidence‐based medicine. The Task Force works to improve the health of all Americans by making evidence‐based recommendations about clinical preventive services such as screenings, counselling services, and preventive medications. All recommendations are published on the Task Force’s website and/or in a peer‐reviewed journal.¹⁵ Cochrane Reviews are systematic reviews of primary research in human healthcare and health policy and are internationally recognized as among the highest standard of evidence‐based healthcare for prevention, treatment, and rehabilitation.¹⁶

To illustrate some of the better‐known relationships of specific antioxidant nutrients, vitamins, and minerals with selected diseases, conditions, and outcomes, several of those most relevant to older adults are summarized in the following sections. The chronic diseases and outcomes addressed include bone health and fracture risk, mild cognitive impairment and dementia, age‐related eye disorders, and cancer and cardiovascular disease, as well as the potential role of nutrient intake (focusing on zinc) in pressure ulcer injury healing. The section that discusses pressure ulcer injuries provides an example of a complex clinical condition in which malnutrition clearly plays a role but for which the causal relationships of specific nutrients are difficult to disentangle from the effects of other comorbidities and conditions. It also shows the challenge presented when a highly reliable biomarker for a given nutrient has not been identified, as is the case for zinc and several other micronutrients.