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Diets

Author/s: 
Mary Yannakoulia, Nikolaos Scarmeas

Food consumption provides essential and nonessential nutrients in the human body and thereby promotes growth and health. Individual food choice and the potential modification of eating habits are complex issues, influenced by the availability and acceptability of foods.1 The availability of foods depends on physical, political, and economic factors. From the myriad foods that are available or potentially available for consumption, the selection is based on socioeconomic, cultural, and individual factors. Individual foods are parts of diets; diets are characterized by nutrient content, clustering of foods, and temporal consumption patterns. The plethora of diets continually expands, and some diets have been extensively investigated.
We review the underlying rationale for and constituents of the most widely recognized, scientifically explored, and broadly promoted diets (Figure 1). We do not review diets for specific nutritional or metabolic deficiencies or many of the constructed dietary indexes. This review is not intended to detail the clinical efficacy of each diet presented, although we briefly outline some of the well-known potential effects on health and the underlying mechanisms. Even though most (but not all) of the dietary modifications have been driven by the desire to control body weight, we consider important health effects independently of adiposity.

Keywords 
diet

The Women’s Health Initiative Randomized Trials and Clinical Practice

Author/s: 
Manson, J.E., Crandall, C.J., Rossouw, J.E.

Importance: Approximately 55 million people in the US and approximately 1.1 billion people worldwide are postmenopausal women. To inform clinical practice about the health effects of menopausal hormone therapy, calcium plus vitamin D supplementation, and a low-fat dietary pattern, the Women's Health Initiative (WHI) enrolled 161 808 postmenopausal US women (N = 68 132 in the clinical trials) aged 50 to 79 years at baseline from 1993 to 1998, and followed them up for up to 20 years.

Observations: The WHI clinical trial results do not support hormone therapy with oral conjugated equine estrogens plus medroxyprogesterone acetate for postmenopausal women or conjugated equine estrogens alone for those with prior hysterectomy to prevent cardiovascular disease, dementia, or other chronic diseases. However, hormone therapy is effective for treating moderate to severe vasomotor and other menopausal symptoms. These benefits of hormone therapy in early menopause, combined with lower rates of adverse effects of hormone therapy in early compared with later menopause, support initiation of hormone therapy before age 60 years for women without contraindications to hormone therapy who have bothersome menopausal symptoms. The WHI results do not support routinely recommending calcium plus vitamin D supplementation for fracture prevention in all postmenopausal women. However, calcium and vitamin D are appropriate for women who do not meet national guidelines for recommended intakes of these nutrients through diet. A low-fat dietary pattern with increased fruit, vegetable, and grain consumption did not prevent the primary outcomes of breast or colorectal cancer but was associated with lower rates of the secondary outcome of breast cancer mortality during long-term follow-up.

Conclusions and relevance: For postmenopausal women, the WHI randomized clinical trials do not support menopausal hormone therapy to prevent cardiovascular disease or other chronic diseases. Menopausal hormone therapy is appropriate to treat bothersome vasomotor symptoms among women in early menopause, without contraindications, who are interested in taking hormone therapy. The WHI evidence does not support routine supplementation with calcium plus vitamin D for menopausal women to prevent fractures or a low-fat diet with increased fruits, vegetables, and grains to prevent breast or colorectal cancer. A potential role of a low-fat dietary pattern in reducing breast cancer mortality, a secondary outcome, warrants further study.

Keywords 
vitamin D calcium menopause Menopausal women Women's Health

Effects of weight loss during a very low carbohydrate diet on specific adipose tissue depots and insulin sensitivity in older adults with obesity: a randomized clinical trial

Author/s: 
Gower, Babara, Goss, Amy, Soleymani, Taraneh, Stewart , Mariah, Pendergrass, May, Lockhart, Mark, Kranz, Olivia, Dowla, Shima, Bush, Nikki, Barry, Valene Garr, Fontaine, Kevin R.

Background: Insulin resistance and accumulation of visceral adipose tissue (VAT) and intermuscular adipose tissue (IMAT) place aging adults with obesity at high risk of cardio-metabolic disease. A very low carbohydrate diet (VLCD) may be a means of promoting fat loss from the visceral cavity and skeletal muscle, without compromising lean mass, and improve insulin sensitivity in aging adults with obesity.

Objective: To determine if a VLCD promotes a greater loss of fat (total, visceral and intermuscular), preserves lean mass, and improves insulin sensitivity compared to a standard CHO-based/low-fat diet (LFD) in older adults with obesity.

Design: Thirty-four men and women aged 60-75 years with obesity (body mass index [BMI] 30-40 kg/m2) were randomized to a diet prescription of either a VLCD (< 10:25:> 65% energy from CHO:protein:fat) or LFD diet (55:25:20) for 8 weeks. Body composition by dual-energy X-ray absorptiometry (DXA), fat distribution by magnetic resonance imaging (MRI), insulin sensitivity by euglycemic hyperinsulinemic clamp, and lipids by a fasting blood draw were assessed at baseline and after the intervention.

Results: Participants lost an average of 9.7 and 2.0% in total fat following the VLCD and LFD, respectively (p < 0.01). The VLCD group experienced ~ 3-fold greater loss in VAT compared to the LFD group (- 22.8% vs - 1.0%, p < 0.001) and a greater decrease in thigh-IMAT (- 24.4% vs - 1.0%, p < 0.01). The VLCD group also had significantly greater thigh skeletal muscle (SM) at 8 weeks following adjustment for change in total fat mass. Finally, the VLCD had greater increases in insulin sensitivity and HDL-C and decreases in fasting insulin and triglycerides compared to the LFD group.

Conclusions: Weight loss resulting from consumption of a diet lower in CHO and higher in fat may be beneficial for older adults with obesity by depleting adipose tissue depots most strongly implicated in poor metabolic and functional outcomes and by improving insulin sensitivity and the lipid profile.

Trial registration: NCT02760641. Registered 03 May 2016 - Retrospectively registered.

© The Author(s) 2020.

Association Between Plant and Animal Protein Intake and Overall and Cause-Specific Mortality

Author/s: 
Huang, J., Liao, L.M., Weinstein, S.J., Sinha, R., Graubard, B.I., Albanes, D.

Importance: Although emphasis has recently been placed on the importance of high-protein diets to overall health, a comprehensive analysis of long-term cause-specific mortality in association with the intake of plant protein and animal protein has not been reported.

Objective: To examine the associations between overall mortality and cause-specific mortality and plant protein intake.

Design, setting, and participants: This prospective cohort study analyzed data from 416 104 men and women in the US National Institutes of Health-AARP Diet and Health Study from 1995 to 2011. Data were analyzed from October 2018 through April 2020.

Exposures: Validated baseline food frequency questionnaire dietary information, including intake of plant protein and animal protein.

Main outcomes and measures: Hazard ratios and 16-year absolute risk differences for overall mortality and cause-specific mortality.

Results: The final analytic cohort included 237 036 men (57%) and 179 068 women. Their overall median (SD) ages were 62.2 (5.4) years for men and 62.0 (5.4) years for women. Based on 6 009 748 person-years of observation, 77 614 deaths (18.7%; 49 297 men and 28 317 women) were analyzed. Adjusting for several important clinical and other risk factors, greater dietary plant protein intake was associated with reduced overall mortality in both sexes (hazard ratio per 1 SD was 0.95 [95% CI, 0.94-0.97] for men and 0.95 [95% CI, 0.93-0.96] for women; adjusted absolute risk difference per 1 SD was -0.36% [95% CI, -0.48% to -0.25%] for men and -0.33% [95% CI, -0.48% to -0.21%] for women; hazard ratio per 10 g/1000 kcal was 0.88 [95% CI, 0.84-0.91] for men and 0.86 [95% CI, 0.82-0.90] for women; adjusted absolute risk difference per 10 g/1000 kcal was -0.95% [95% CI, -1.3% to -0.68%] for men and -0.86% [95% CI, -1.3% to -0.55%] for women; all P < .001). The association between plant protein intake and overall mortality was similar across the subgroups of smoking status, diabetes, fruit consumption, vitamin supplement use, and self-reported health status. Replacement of 3% energy from animal protein with plant protein was inversely associated with overall mortality (risk decreased 10% in both men and women) and cardiovascular disease mortality (11% lower risk in men and 12% lower risk in women). In particular, the lower overall mortality was attributable primarily to substitution of plant protein for egg protein (24% lower risk in men and 21% lower risk in women) and red meat protein (13% lower risk in men and 15% lower risk in women).

Conclusions and relevance: In this large prospective cohort, higher plant protein intake was associated with small reductions in risk of overall and cardiovascular disease mortality. Our findings provide evidence that dietary modification in choice of protein sources may influence health and longevity.

Conflict of interest statement

Conflict of Interest Disclosures: None reported.

Clinical Practice Guideline: Ménière's Disease Executive Summary

Author/s: 
Basura, GJ, Adams, ME, Monfared, A, Schwartz, SR, Antonelli, PJ, Burkard, R, Bush, ML, Bykowski, J, Colandrea, M, Derebery, J, Kelly, EA, Kerber, KA, Koopman, CF, Kuch, AA, Marcolini, E, McKinnon, BJ, Ruckenstein, MJ, Valenzuela, CV, Vosooney,A, Walsh, SA, Nnacheta, LC, Dhepyasuwan, N, Buchanan, EM

OBJECTIVE:

Ménière's disease (MD) is a clinical condition defined by spontaneous vertigo attacks (each lasting 20 minutes to 12 hours) with documented low- to midfrequency sensorineural hearing loss in the affected ear before, during, or after one of the episodes of vertigo. It also presents with fluctuating aural symptoms (hearing loss, tinnitus, or ear fullness) in the affected ear. The underlying etiology of MD is not completely clear, yet it has been associated with inner ear fluid volume increases, culminating in episodic ear symptoms (vertigo, fluctuating hearing loss, tinnitus, and aural fullness). Physical examination findings are often unremarkable, and audiometric testing may or may not show low- to midfrequency sensorineural hearing loss. Imaging, if performed, is also typically normal. The goals of MD treatment are to prevent or reduce vertigo severity and frequency; relieve or prevent hearing loss, tinnitus, and aural fullness; and improve quality of life. Treatment approaches to MD are many, and approaches typically include modifications of lifestyle factors (eg, diet) and medical, surgical, or a combination of therapies.

PURPOSE:

The primary purpose of this clinical practice guideline is to improve the quality of the diagnostic workup and treatment outcomes of MD. To achieve this purpose, the goals of this guideline are to use the best available published scientific and/or clinical evidence to enhance diagnostic accuracy and appropriate therapeutic interventions (medical and surgical) while reducing unindicated diagnostic testing and/or imaging.

Keywords 
Meniett device electrocochleography endolymphatic hydrops endolymphatic sac decompression fluctuating aural symptoms gentamicin labyrinthectomy sensorineural hearing loss sodium-restricted diet vestibular testing

Can We Say What Diet Is Best for Health?

Author/s: 
Katz, DL, Meller, S

Diet is established among the most important influences on health in modern societies. Injudicious diet figures among the leading causes of premature death and chronic disease. Optimal eating is associated with increased life expectancy, dramatic reduction in lifetime risk of all chronic disease, and amelioration of gene expression. In this context, claims abound for the competitive merits of various diets relative to one another. Whereas such claims, particularly when attached to commercial interests, emphasize distinctions, the fundamentals of virtually all eating patterns associated with meaningful evidence of health benefit overlap substantially. There have been no rigorous, long-term studies comparing contenders for best diet laurels using methodology that precludes bias and confounding, and for many reasons such studies are unlikely. In the absence of such direct comparisons, claims for the established superiority of any one specific diet over others are exaggerated. The weight of evidence strongly supports a theme of healthful eating while allowing for variations on that theme. A diet of minimally processed foods close to nature, predominantly plants, is decisively associated with health promotion and disease prevention and is consistent with the salient components of seemingly distinct dietary approaches. Efforts to improve public health through diet are forestalled not for want of knowledge about the optimal feeding of Homo sapiens but for distractions associated with exaggerated claims, and our failure to convert what we reliably know into what we routinely do. Knowledge in this case is not, as of yet, power; would that it were so.

Keywords 
diet nutrition lifestyle Health disease

Influence of changes in diet quality on unhealthy aging: the Seniors-ENRICA cohort

Author/s: 
Ortolá, Rosario, García-Esquinas, Esther, García-Varela, Giselle, Struijkab, Ellen A., Rodríguez-Artalejo, Fernando, Lopez-Garcia, Esther

Background

Whether adopting a better diet in late life influences the aging process is still uncertain. Thus, we examined the association between changes in diet quality and unhealthy aging.

Methods

Data came from 2042 individuals aged ≥ 60 years recruited in the Seniors-ENRICA cohort in 2008–2010 (wave 0) and followed-up in 2012 (wave 1) and 2015 (wave 2). Diet quality was assessed with the Mediterranean Diet Adherence Screener (MEDAS), the Mediterranean Diet Score (MDS) and the Alternate Healthy Eating Index-2010 (AHEI-2010) at waves 0 and 1. Unhealthy ageing was measured using a 52-item health deficit accumulation index with 4 domains (functional, self-rated health/vitality, mental health, and morbidity/health services use) at each wave. An increase in dietary indices represents a diet improvement, and a lower deficit accumulation index indicates a health improvement.

Results

Compared with participants with a > 1-point decrease in MEDAS or MDS, those with a > 1-point increase showed lower deficit accumulation from wave 0 to wave 2 (multivariate β [95% CI]: –1.49 [− 2.88 to − 0.10], p-trend = 0.04 for MEDAS; and − 2.20 [− 3.56 to − 0.84], p-trend = 0.002 for MDS) and from wave 1 to wave 2 (− 1.34 [− 2.60 to − 0.09], p-trend = 0.04 for MEDAS). Also, participants with a > 5-point increase in AHEI-2010 showed lower deficit accumulation from wave 0 to wave 1 (− 1.15 [− 2.01 to − 0.28], p-trend = 0.009) and from wave 0 to wave 2 (− 1.21 [− 2.31 to − 0.10], p-trend = 0.03) than those with a > 5-point decrease. These results were mostly due to a strong association between improved diet quality and less functional deterioration.

Conclusions

In older adults, adopting a better diet was associated with less deficit accumulation, particularly functional deterioration. Improving dietary habits may delay unhealthy ageing. Our results have clinical relevance since we have observed that the deficit accumulation index decreases an average of 0.74 annually.

Keywords 
cohort study dietary patterns aging

Effect of a Long Bout Versus Short Bouts of Walking on Weight Loss During a Weight‐Loss Diet: A Randomized Trial

Author/s: 
Madjd, Amenah, Taylor, Moira A., Delavari, Alireza,, Reza, Macdonald, Ian A., Farshchi, Hamid R.

OBJECTIVE:

This study aimed to evaluate the effect of different daily physical activity (PA) frequencies, while maintaining the same daily volume of PA, on weight loss, carbohydrate metabolism, and lipid metabolism in women with overweight or obesity throughout a 24-week intervention.

METHODS:

During their weight-loss plan, 65 women (BMI = 27-35 kg/m2 ; age = 18-40 years) who had a sedentary lifestyle were randomly allocated to the following groups: diet plus a long bout of moderate physical activity (LBP) (one 50-minute bout of moderate-intensity PA) 6 d/wk or diet plus short bouts of moderate physical activity (SBP) (two 25-minute bouts of moderate-intensity PA) 6 d/wk. Anthropometric and blood measurements were taken at baseline and at 24 weeks.

RESULTS:

Compared with the LBP group, the SBP group had a greater decrease in weight (SBP: -8.08 ± 2.20 kg; LBP: -6.39 ± 2.28 kg; P = 0.019), BMI (SBP: -3.11 ± 0.87 kg/m2 ; LBP: -2.47 ± 0.86 kg/m2 ; P = 0.027), and waist circumference (SBP: -8.78 ± 2.62 cm; LBP: -5.76 ± 2.03 cm; P = 0.026). No significant differences were seen in carbohydrate and lipid metabolism characteristics after 24 weeks.

CONCLUSIONS:

PA undertaken in two shorter bouts per day could be more effective for weight loss than PA undertaken in a daily long bout in adult women in a 24-week weight-loss program.

Keywords 
obesity diet weight loss exercise

Primary care-led weight management for remission of type 2 diabetes (DiRECT): an open-label, cluster-randomised trial

Author/s: 
Lean, Michael E.J., Leslie, Wilma S., Barnes, Alison C., Brosnahan, Naomi, Thom, George, McCombie, Louise, Peters, Carl, Zhyzhneuskaya, Sviatlana, Al-Mrabeh, Ahmad, Hollingsworth, Kieren G., Rodrigues, Angela M., Rehackova, Lucia, Adamson, Ashley J., Sniehotta, Falko F., Mathers, John C., Ross, Hazel M., McIlvenna, Yvonne, Stefanetti, Renae, Trenell, Michael, Welsh, Paul, Kean, Sharon, Ford, Ian, McConnachie, Alex, Sattar, Naveed, Taylor, Roy

BACKGROUND:

Type 2 diabetes is a chronic disorder that requires lifelong treatment. We aimed to assess whether intensive weight management within routine primary care would achieve remission of type 2 diabetes.

METHODS:

We did this open-label, cluster-randomised trial (DiRECT) at 49 primary care practices in Scotland and the Tyneside region of England. Practices were randomly assigned (1:1), via a computer-generated list, to provide either a weight management programme (intervention) or best-practice care by guidelines (control), with stratification for study site (Tyneside or Scotland) and practice list size (>5700 or ≤5700). Participants, carers, and research assistants who collected outcome data were aware of group allocation; however, allocation was concealed from the study statistician. We recruited individuals aged 20-65 years who had been diagnosed with type 2 diabetes within the past 6 years, had a body-mass index of 27-45 kg/m2, and were not receiving insulin. The intervention comprised withdrawal of antidiabetic and antihypertensive drugs, total diet replacement (825-853 kcal/day formula diet for 3-5 months), stepped food reintroduction (2-8 weeks), and structured support for long-term weight loss maintenance. Co-primary outcomes were weight loss of 15 kg or more, and remission of diabetes, defined as glycated haemoglobin (HbA1c) of less than 6·5% (<48 mmol/mol) after at least 2 months off all antidiabetic medications, from baseline to 12 months. These outcomes were analysed hierarchically. This trial is registered with the ISRCTN registry, number 03267836.

FINDINGS:

Between July 25, 2014, and Aug 5, 2017, we recruited 306 individuals from 49 intervention (n=23) and control (n=26) general practices; 149 participants per group comprised the intention-to-treat population. At 12 months, we recorded weight loss of 15 kg or more in 36 (24%) participants in the intervention group and no participants in the control group (p<0·0001). Diabetes remission was achieved in 68 (46%) participants in the intervention group and six (4%) participants in the control group (odds ratio 19·7, 95% CI 7·8-49·8; p<0·0001). Remission varied with weight loss in the whole study population, with achievement in none of 76 participants who gained weight, six (7%) of 89 participants who maintained 0-5 kg weight loss, 19 (34%) of 56 participants with 5-10 kg loss, 16 (57%) of 28 participants with 10-15 kg loss, and 31 (86%) of 36 participants who lost 15 kg or more. Mean bodyweight fell by 10·0 kg (SD 8·0) in the intervention group and 1·0 kg (3·7) in the control group (adjusted difference -8·8 kg, 95% CI -10·3 to -7·3; p<0·0001). Quality of life, as measured by the EuroQol 5 Dimensions visual analogue scale, improved by 7·2 points (SD 21·3) in the intervention group, and decreased by 2·9 points (15·5) in the control group (adjusted difference 6·4 points, 95% CI 2·5-10·3; p=0·0012). Nine serious adverse events were reported by seven (4%) of 157 participants in the intervention group and two were reported by two (1%) participants in the control group. Two serious adverse events (biliary colic and abdominal pain), occurring in the same participant, were deemed potentially related to the intervention. No serious adverse events led to withdrawal from the study.

INTERPRETATION:

Our findings show that, at 12 months, almost half of participants achieved remission to a non-diabetic state and off antidiabetic drugs. Remission of type 2 diabetes is a practical target for primary care.

Keywords 
diet diabetes type 2 diabetes

Antioxidants: In Depth

Author/s: 
National Institutes of Health, Chun, Ock, Frei, Balz, Gardner, Christopher, Alekel, D. Lee, Killen, John Jr.

Antioxidants are man-made or natural substances that may prevent or delay some types of cell damage. Diets high in vegetables and fruits, which are good sources of antioxidants, have been found to be healthy; however, research has not shown antioxidant supplements to be beneficial in preventing diseases. Examples of antioxidants include vitamins C and E, selenium, and carotenoids, such as beta-carotene, lycopene, lutein, and zeaxanthin. This fact sheet provides basic information about antioxidants, summarizes what the science says about antioxidants and health, and suggests sources for additional information.

Keywords 
antioxidants diet dietary supplements
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