Journal Article

A systematic review and meta-analysis of randomized trials of substituting soymilk for cow’s milk and intermediate cardiometabolic outcomes: understanding the impact of dairy alternatives in the transition to plant-based diets on cardiometabolic health

Sievenpiper, J. L., Erlich, M. N., Kendall, C. W. C., Chiavaroli, L., Zurbau, A., Almneni, A., Messina, M., Leiter, L. A., Ayoub-Charette, S., Jenkins, D. J. A., Blanco Mejia, S., Bazinet, R. P., Ghidanac, D., Khan, T. A.

2024

Overview

Background Dietary guidelines recommend a shift to plant-based diets. Fortified soymilk, a prototypical plant protein food used in the transition to plant-based diets, usually contains added sugars to match the sweetness of cow’s milk and is classified as an ultra-processed food. Whether soymilk can replace minimally processed cow’s milk without the adverse cardiometabolic effects attributed to added sugars and ultra-processed foods remains unclear. We conducted a systematic review and meta-analysis of randomized controlled trials, to assess the effect of substituting soymilk for cow’s milk and its modification by added sugars (sweetened versus unsweetened) on intermediate cardiometabolic outcomes. Methods MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched (through June 2024) for randomized controlled trials of ≥ 3 weeks in adults. Outcomes included established markers of blood lipids, glycemic control, blood pressure, inflammation, adiposity, renal disease, uric acid, and non-alcoholic fatty liver disease. Two independent reviewers extracted data and assessed risk of bias. The certainty of evidence was assessed using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). A sub-study of lactose versus sucrose outside of a dairy-like matrix was conducted to explore the role of sweetened soymilk which followed the same methodology. Results Eligibility criteria were met by 17 trials ( n  = 504 adults with a range of health statuses), assessing the effect of a median daily dose of 500 mL of soymilk (22 g soy protein and 17.2 g or 6.9 g/250 mL added sugars) in substitution for 500 mL of cow’s milk (24 g milk protein and 24 g or 12 g/250 mL total sugars as lactose) on 19 intermediate outcomes. The substitution of soymilk for cow’s milk resulted in moderate reductions in non-HDL-C (mean difference, − 0.26 mmol/L [95% confidence interval, − 0.43 to − 0.10]), systolic blood pressure (− 8.00 mmHg [− 14.89 to − 1.11]), and diastolic blood pressure (− 4.74 mmHg [− 9.17 to − 0.31]); small important reductions in LDL-C (− 0.19 mmol/L [− 0.29 to − 0.09]) and c-reactive protein (CRP) (− 0.82 mg/L [− 1.26 to − 0.37]); and trivial increases in HDL-C (0.05 mmol/L [0.00 to 0.09]). No other outcomes showed differences. There was no meaningful effect modification by added sugars across outcomes. The certainty of evidence was high for LDL-C and non-HDL-C; moderate for systolic blood pressure, diastolic blood pressure, CRP, and HDL-C; and generally moderate-to-low for all other outcomes. We could not conduct the sub-study of the effect of lactose versus added sugars, as no eligible trials could be identified. Conclusions Current evidence provides a good indication that replacing cow’s milk with soymilk (including sweetened soymilk) does not adversely affect established cardiometabolic risk factors and may result in advantages for blood lipids, blood pressure, and inflammation in adults with a mix of health statuses. The classification of plant-based dairy alternatives such as soymilk as ultra-processed may be misleading as it relates to their cardiometabolic effects and may need to be reconsidered in the transition to plant-based diets. Trial registration ClinicalTrials.gov identifier, NCT05637866.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Adipose tissue / Adult / Adults / Alternatives / Bias / Biomedicine / Blood lipids / Blood pressure / Blood Pressure - physiology / Body mass index / C-reactive protein / Cardiopulmonary system / Cardiovascular disease / Cardiovascular Diseases - prevention & control / Cardiovascular system / Cattle / Cholesterol / Clinical trials / Cow's milk / Creatinine / Dairy industry / Dairy products / Diet / Diet, Plant-Based / Dietary guidelines / Fatty liver / Food / Food plants / Food processing / Funding / Glucose / Health aspects / Health care / Health risks / High density lipoprotein / Humans / Impact analysis / Inflammation / Intervention / Kidney diseases / Lactose / Lipids / Lipoproteins / Liver / Liver diseases / Low density lipoprotein / Low density lipoproteins / Medical research / Medicine / Medicine & Public Health / Medicine, Experimental / Meta-analysis / Metabolism / Milk / Milk proteins / Nutrition / Physiological aspects / Plant-based beverages / Processed foods / Proteins / Randomized controlled feeding trials / Randomized Controlled Trials as Topic / Research Article / Risk assessment / Risk factors / Soy Milk - administration & dosage / Soy protein / Soybean milk / Soymilk / Substitutes / Sucrose / Sugar / Sweetness / Systematic review / Testing / Uric acid / Vegetarianism