Research Articles

Science supports meat

Meat and mental health: A meta-analysis of meat consumption, depression, and anxiety

URL: https://www.tandfonline.com/doi/full/10.1080/10408398.2021.1974336

Journal: Critical Reviews in Food Science and Nutrition

Publication Date: 10/2021

Summary: In this meta-analysis, we examined the quantitative relation between meat consumption or avoidance, depression, and anxiety. in June 2020, we searched five online databases for primary studies examining differences in depression and anxiety between meat abstainers and meat consumers that offered a clear (dichotomous) distinction between these groups. Twenty studies met the selection criteria representing 171,802 participants with 157,778 meat consumers and 13,259 meat abstainers. we calculated the magnitude of the effect between meat consumers and meat abstainers with bias correction (Hedges’s g effect size) where higher and positive scores reflect better outcomes for meat consumers. Meat consumption was associated with lower depression (Hedges’s g=0.216, 95% Ci [0.14 to 0.30], p < .001) and lower anxiety (g=0.17, 95% Ci [0.03 to 0.31], p = .02) compared to meat abstention. Compared to vegans, meat consumers experienced both lower depression (g=0.26, 95% Ci [0.01 to 0.51], p = .041) and anxiety (g=0.15, 95% Ci [-0.40 to 0.69], p = .598). Sex did not modify these relations. Study quality explained 58% and 76% of between-studies heterogeneity in depression and anxiety, respectively. The analysis also showed that the more rigorous the study, the more positive and consistent the relation between meat consumption and better mental health. The current body of evidence precludes causal and temporal inferences.

Effect of Lower Versus Higher Red Meat Intake on Cardiometabolic and Cancer Outcomes: A Systematic Review of Randomized Trials

URL: https://annals.org/aim/fullarticle/2752326/effect-lower-versus-higher-red-meat-intake-cardiometabolic-cancer-outcomes

Journal: Annals of Internal Medicine

Publication Date: 10/2019

Summary: Low- to very-low-certainty evidence suggests that diets restricted in red meat may have little or no effect on major cardiometabolic outcomes and cancer mortality and incidence.

Behavioral Characteristics and Self-reported Health Status Among 2029 Adults Consuming a “Carnivore Diet”

URL: https://academic.oup.com/cdn/advance-article/doi/10.1093/cdn/nzab133/6415894

Journal: Clinical Developments in Nutrition

Publication Date: 11/2021

Summary: The “carnivore diet,” based on animal foods and excluding most or all plant foods, has attracted recent popular attention. However, little is known about the health effects and tolerability of this diet, and concerns for nutrient deficiencies and cardiovascular disease risk have been raised. We obtained descriptive data on the nutritional practices and health status of a large group of carnivore diet consumers. A social media survey was conducted March 30 to June 24, 2020 among adults self- identifying as consuming a carnivore diet ≥ 6 months. Survey questions interrogated motivation, dietary intake patterns, symptoms suggestive of nutritional deficiencies or other adverse effects, satisfaction, prior and current health conditions, anthropometrics, and laboratory data.  A total of 2029 respondents (median age 44 years, 67% male), reported consuming a carnivore diet for 14 (interquartile range 9–20) months, motivated primarily by health reasons (93%). Red meat consumption was reported ≥ daily by 85%. Under 10% reported consuming vegetables, fruits or grains > monthly, and 37% denied vitamin supplement use. Prevalence of adverse symptoms was low (<1% to 5.5%). Symptoms included gastrointestinal (3.1–5.5%), muscular (4.0%), and dermatologic (1.1–1.9%). Participants reported high levels of satisfaction and improvements in overall health (95%), wellbeing (69–91%), various medical conditions (48–93%) and BMI (from 27.2 [23.5–31.9] to 24.3 [22.1–27.0] kg/m2). Among a subset reporting current lipids, LDL-cholesterol was markedly elevated (172 mg/dL), whereas HDL-cholesterol (68 gm/dL) and triglycerides (68 mg/dL) were optimal. Participants with diabetes reported benefits including reductions in BMI (4.3 kg/m2, 1.4–7.2), HbA1C (0.4%, 0–1.7), and diabetes medication use (84–100%). Contrary to common expectations, adults consuming a carnivore diet experienced few adverse effects and instead reported health benefits and high satisfaction. Cardiovascular risk factors were variably affected. The generalizability of these findings and the long-term effects of this dietary pattern require further study. In a survey of over 2000 adults following a “carnivore diet” (i.e., one that aims to avoid plant foods), health benefits and satisfaction were generally reported.

Dietary Intake of Red Meat, Processed Meat, and Poultry and Risk of Colorectal Cancer and All-Cause Mortality in the Context of Dietary Guideline Compliance

URL: https://www.mdpi.com/2072-6643/13/1/32

Journal: Nutrients

Publication Date: 12/2020

Summary: Meat intake has been linked to increased risk of colorectal cancer (CRC) and mortality. However, diet composition may affect the risks. We aimed to estimate associations between red and processed meat and poultry intake and risk of CRC and all-cause mortality and if they are modified by dietary quality using Cox regression analyses. Baseline dietary data were obtained from three survey rounds of the Danish National Survey on Diet and Physical Activity. Data on CRC and all-cause mortality were extracted from national registers. The cohort was followed from date of survey interview—or for CRC, from age 50 years, whichever came last, until 31 December 2017. Meat intake was analysed categorically and continuously, and stratified by dietary quality for 15–75-year-old Danes at baseline, n 6282 for CRC and n 9848 for mortality analyses. We found no significant association between red and processed meat intake and CRC risk. For poultry, increased CRC risk for high versus low intake (HR 1.62; 95%CI 1.13–2.31) was found, but not when examining risk change per 100 g increased intake. We showed no association between meat intake and all-cause mortality. The association between meat intake and CRC or mortality risk was not modified by dietary quality.

Effect of a 90 g/day low-carbohydrate diet on glycaemic control, small, dense low-density lipoprotein and carotid intima-media thickness in type 2 diabetic patients: An 18-month randomised controlled trial

URL: https://pubmed.ncbi.nlm.nih.gov/33017456/

Journal: PLoS One

Publication Date: 10/2020

Summary: This study explored the effect of a moderate (90 g/d) low-carbohydrate diet (LCD) in type 2 diabetes patients over 18 months. Ninety-two poorly controlled type 2 diabetes patients aged 20-80 years with HbA1c ≥7.5% (58 mmol/mol) in the previous three months were randomly assigned to a 90 g/d LCD r traditional diabetic diet (TDD). The primary outcomes were glycaemic control status and change in medication effect score (MES). The secondary outcomes were lipid profiles, small, dense low-density lipoprotein (sdLDL), serum creatinine, microalbuminuria and carotid intima-media thickness (IMT). A total of 85 (92.4%) patients completed 18 months of the trial. At the end of the study, the LCD and TDD group consumed 88.0±29.9 g and 151.1±29.8 g of carbohydrates, respectively (p < 0.05). The 18-month mean change from baseline was statistically significant for the HbA1c (-1.6±0.3 vs. -1.0±0.3%), 2-h glucose (-94.4±20.8 vs. -18.7±25.7 mg/dl), MES (-0.42±0.32 vs. -0.05±0.24), weight (-2.8±1.8 vs. -0.7±0.7 kg), waist circumference (-5.7±2.7 vs. -1.9±1.4 cm), hip circumference (-6.1±1.8 vs. -2.9±1.7 cm) and blood pressure (-8.3±4.6/-5.0±3 vs. 1.6±0.5/2.5±1.6 mmHg) between the LCD and TDD groups (p<0.05). The 18-month mean change from baseline was not significantly different in lipid profiles, sdLDL, serum creatinine, microalbuminuria, alanine aminotransferase (ALT) and carotid IMT between the groups. A moderate (90 g/d) LCD showed better glycaemic control with decreasing MES, lowering blood pressure, decreasing weight, waist and hip circumference without adverse effects on lipid profiles, sdLDL, serum creatinine, microalbuminuria, ALT and carotid IMT than TDD for type 2 diabetic patients.

 

Beneficial effects of ketogenic diet in obese diabetic subjects

URL: https://link.springer.com/article/10.1007%2Fs11010-007-9448-z

Journal: Molecular and Cellular Biochemistry

Publication Date: 04/2007

Summary: Obesity is closely linked to the incidence of type II diabetes. It is found that effective management of body weight and changes to nutritional habits especially with regard to the carbohydrate content and glycemic index of the diet have beneficial effects in obese subjects with glucose intolerance. Previously we have shown that ketogenic diet is quite effective in reducing body weight. Furthermore, it favorably alters the cardiac risk factors even in hyperlipidemic obese subjects. In this study the effect of ketogenic diet in obese subjects with high blood glucose level is compared to those with normal blood glucose level for a period of 56 weeks. A total of 64 healthy obese subjects with body mass index (BMI) greater than 30, having high blood glucose level and those subjects with normal blood glucose level were selected in this study. The body weight, body mass index, blood glucose level, total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, urea and creatinine were determined before and at 8, 16, 24, 48, and 56 weeks after the administration of the ketogenic diet. The body weight, body mass index, the level of blood glucose, total cholesterol, LDL-cholesterol, triglycerides, and urea showed a significant decrease from week 1 to week 56 (P < 0.0001), whereas the level of HDL-cholesterol increased significantly (P < 0.0001). Interestingly these changes were more significant in subjects with high blood glucose level as compared to those with normal blood glucose level. The changes in the level of creatinine were not statistically significant. This study shows the beneficial effects of ketogenic diet in obese diabetic subjects following its long-term administration. Furthermore, it demonstrates that in addition to its therapeutic value, low carbohydrate diet is safe to use for a longer period of time in obese diabetic subjects.

The effect of a low-carbohydrate, ketogenic diet on nonalcoholic fatty liver disease: a pilot study

URL: https://link.springer.com/article/10.1007%2Fs10620-006-9433-5

Journal: Digestive Diseases and Sciences

Publication Date: 02/2007

Summary: Nonalcoholic fatty liver disease is an increasingly common condition that may progress to hepatic cirrhosis. This pilot study evaluated the effects of a low-carbohydrate, ketogenic diet on obesity-associated fatty liver disease. Five patients with a mean body mass index of 36.4 kg/m2 and biopsy evidence of fatty liver disease were instructed to follow the diet (<20 g/d of carbohydrate) with nutritional supplementation for 6 months. Patients returned for group meetings biweekly for 3 months, then monthly for the second 3 months. The mean weight change was −12.8 kg (range 0 to −25.9 kg). Four of 5 posttreatment liver biopsies showed histologic improvements in steatosis (P=.02) inflammatory grade (P=.02), and fibrosis (P=.07). Six months of a low-carbohydrate, ketogenic diet led to significant weight loss and histologic improvement of fatty liver disease. Further research is into this approach is warranted.

Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum

URL: https://academic.oup.com/ajcn/article/87/1/44/4633256

Journal: American Journal of Clinical Nutrition

Publication Date: 01/2008

Summary: Altering the macronutrient composition of the diet influences hunger and satiety. Studies have compared high- and low-protein diets, but there are few data on carbohydrate content and ketosis on motivation to eat and ad libitum intake. We aimed to compare the hunger, appetite, and weight-loss responses to a high-protein, low-carbohydrate [(LC) ketogenic] and those to a high-protein, medium-carbohydrate [(MC) nonketogenic] diet in obese men feeding ad libitum. Seventeen obese men were studied in a residential trial; food was provided daily. Subjects were offered 2 high-protein (30% of energy) ad libitum diets, each for a 4-wk period-an LC (4% carbohydrate) ketogenic diet and an MC (35% carbohydrate) diet-randomized in a crossover design. Body weight was measured daily, and ketosis was monitored by analysis of plasma and urine samples. Hunger was assessed by using a computerized visual analogue system. Ad libitum energy intakes were lower with the LC diet than with the MC diet [P=0.02; SE of the difference (SED): 0.27] at 7.25 and 7.95 MJ/d, respectively. Over the 4-wk period, hunger was significantly lower (P=0.014; SED: 1.76) and weight loss was significantly greater (P=0.006; SED: 0.62) with the LC diet (6.34 kg) than with the MC diet (4.35 kg). The LC diet induced ketosis with mean 3-hydroxybutyrate concentrations of 1.52 mmol/L in plasma (P=0.036 from baseline; SED: 0.62) and 2.99 mmol/L in urine (P<0.001 from baseline; SED: 0.36). In the short term, high-protein, low-carbohydrate ketogenic diets reduce hunger and lower food intake significantly more than do high-protein, medium-carbohydrate nonketogenic diets.

The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633336/

Journal: Nutrition and Metabolism

Publication Date: 12/2008

Summary: Dietary carbohydrate is the major determinant of postprandial glucose levels, and several clinical studies have shown that low-carbohydrate diets improve glycemic control. In this study, we tested the hypothesis that a diet lower in carbohydrate would lead to greater improvement in glycemic control over a 24-week period in patients with obesity and type 2 diabetes mellitus. Eighty-four community volunteers with obesity and type 2 diabetes were randomized to either a low-carbohydrate, ketogenic diet (<20 g of carbohydrate daily; LCKD) or a low-glycemic, reduced-calorie diet (500 kcal/day deficit from weight maintenance diet; LGID). Both groups received group meetings, nutritional supplementation, and an exercise recommendation. The main outcome was glycemic control, measured by hemoglobin A1c. Forty-nine (58.3%) participants completed the study. Both interventions led to improvements in hemoglobin A1c, fasting glucose, fasting insulin, and weight loss. The LCKD group had greater improvements in hemoglobin A1c (-1.5% vs. -0.5%, p = 0.03), body weight (-11.1 kg vs. -6.9 kg, p = 0.008), and high density lipoprotein cholesterol (+5.6 mg/dL vs. 0 mg/dL, p < 0.001) compared to the LGID group. Diabetes medications were reduced or eliminated in 95.2% of LCKD vs. 62% of LGID participants (p < 0.01). Dietary modification led to improvements in glycemic control and medication reduction/elimination in motivated volunteers with type 2 diabetes. The diet lower in carbohydrate led to greater improvements in glycemic control, and more frequent medication reduction/elimination than the low glycemic index diet. Lifestyle modification using low carbohydrate interventions is effective for improving and reversing type 2 diabetes.

Comparison of Low Fat and Low Carbohydrate Diets on Circulating Fatty Acid Composition and Markers of Inflammation

URL: https://link.springer.com/article/10.1007/s11745-007-3132-7

Journal: Lipids

Publication Date: 11/2007

Summary: Abnormal distribution of plasma fatty acids and increased inflammation are prominent features of metabolic syndrome. We tested whether these components of metabolic syndrome, like dyslipidemia and glycemia, are responsive to carbohydrate restriction. Overweight men and women with atherogenic dyslipidemia consumed ad libitum diets very low in carbohydrate (VLCKD) (1504 kcal:%CHO:fat:protein = 12:59:28) or low in fat (LFD) (1478 kcal:%CHO:fat:protein = 56:24:20) for 12 weeks. In comparison to the LFD, the VLCKD resulted in an increased proportion of serum total n-6 PUFA, mainly attributed to a marked increase in arachidonate (20:4n-6), while its biosynthetic metabolic intermediates were decreased. The n-6/n-3 and arachidonic/eicosapentaenoic acid ratio also increased sharply. Total saturated fatty acids and 16:1n-7 were consistently decreased following the VLCKD. Both diets significantly decreased the concentration of several serum inflammatory markers, but there was an overall greater anti-inflammatory effect associated with the VLCKD, as evidenced by greater decreases in TNF-α, IL-6, IL-8, MCP-1, E-selectin, I-CAM, and PAI-1. Increased 20:4n-6 and the ratios of 20:4n-6/20:5n-3 and n-6/n-3 are commonly viewed as pro-inflammatory, but unexpectedly were consistently inversely associated with responses in inflammatory proteins. In summary, a very low carbohydrate diet resulted in profound alterations in fatty acid composition and reduced inflammation compared to a low fat diet.

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