Plant-based diets are associated with numerous health benefits, including reduced risks of chronic diseases. However, questions persist regarding the implications of lower dietary intakes of certain non-essential nutrients, such as retinol, vitamin K2, carnitine, and creatine, which are primarily found in animal-derived foods. This narrative review evaluates the roles of these nutrients in human physiology and examines whether their absence in plant-based diets is likely to impact health outcomes. Retinol requirements can be met through the consumption of provitamin A carotenoids in plant foods, even in individuals with reduced conversion efficiency. Endogenous synthesis adequately supports physiological needs for vitamin K2, and currently available evidence does not consistently demonstrate that dietary vitamin K2 provides additional benefits for bone or cardiovascular health. Carnitine and creatine levels may differ between individuals following omnivorous and plant-based diets, but these differences do not result in compromised muscle function, cognitive health, or metabolic outcomes. Current evidence does not indicate that the absence of these non-essential nutrients in plant-based diets adversely affects health or confers disadvantages compared to omnivorous diets.

Within the past several years, a primarily social media-driven controversy about the healthfulness of seed oils has emerged in the US and, to a lesser extent, in other geographical regions. When re...

The carnivore diet consists of meat, fish, eggs, and animal fats, and excludes all plant-based foods. Controlled prospective studies have not evaluated the implications of the carnivore diet for cardiovascular safety, and the existing evidence base remains limited in quality and scope. This narrative review evaluated the scientific literature on the carnivore diet to assess nutrient adequacy, metabolic effects, and alignment with established dietary guidelines for cardiovascular disease (CVD) prevention. We searched PubMed and Google Scholar through April 2026. Eligible studies included modeling research, surveys, case reports, and reviews of carnivore diets; findings from ketogenic and low-carbohydrate diets were drawn upon extensively, given the absence of carnivore-specific trial data. Carnivore diets provide high intakes of saturated fat, cholesterol, sodium, heme iron, and protein and lack fiber and essential nutrients such as folate, vitamin C, magnesium, and potassium. Reported short-term benefits (e.g., improved glycemic control, weight loss, and elevated HDL-cholesterol) are derived primarily from self-reported survey data and case reports, and are therefore highly susceptible to selection, recall, and reporting biases, alongside the absence of objective clinical verification. Significant elevations in total and LDL-cholesterol were also documented. The carnivore diet is inconsistent with public health guidelines recommending plant-based dietary patterns for CVD risk reduction, and current evidence does not support its long-term safety. Based on currently available evidence, the carnivore diet cannot be considered a heart-healthy eating pattern; however, well-designed prospective trials are needed to definitively characterize its long-term cardiovascular effects.

Chronic noncommunicable diseases, including cardiovascular disease (CVD), type 2 diabetes (T2D), and cancer, constitute leading causes of global mortality, with suboptimal diet identified as a primary modifiable risk factor. Plant-based dietary patterns (PBDPs) can be conceptualized along a continuum of quality, with whole-food PBDPs consistently linked to lower risks of CVD, T2D, and all-cause mortality, though much of this evidence derives from studies of vegan or healthy plant-based dietary index patterns rather than whole-plant-food diets directly. Evidence further indicates that minimizing or eliminating added salt, oil, and sugar (SOS) within whole-food PBDPs may provide additional cardiometabolic benefits, primarily by favorably modifying three graded intermediate biomarkers: low-density lipoprotein cholesterol (LDL-C), blood pressure (BP), and adiposity. Dietary sodium increases BP in a linear, dose-dependent manner and enhances food palatability, potentially promoting passive overconsumption and increased adiposity. Although added oil is preferable to saturated fat for LDL-C reduction, preliminary evidence suggests that adding olive oil to an already oil-restricted whole-food PBDP may reduce its LDL-C and body-weight benefits; these findings are hypothesis-generating and require confirmation in larger, longer-term trials. Whole-food fat sources such as nuts and seeds may offer cardiovascular benefits at least equivalent to those of oils, without this attenuating effect. Added sugar promotes excess caloric intake, contributing to increased adiposity, and may impair insulin sensitivity; these effects are most clearly and consistently established for sugar-sweetened beverages (SSBs), whereas the evidence for solid added sugars is weaker and may depend more on excess energy intake and broader dietary context. This narrative review synthesizes evidence from systematic reviews, meta-analyses, Mendelian randomization studies, and key clinical trials to evaluate whether whole-food PBDPs minimizing or eliminating SOS may provide incremental benefit for chronic disease risk reduction and management compared to whole-food PBDPs that include these additives. Direct long-term randomized evidence comparing SOS-restricted to SOS-inclusive whole-food PBDPs remains limited, and the possible incremental benefit of SOS restriction within an already health-promoting dietary pattern warrants further investigation. Complete SOS elimination has not yet been shown to provide incremental benefit beyond a high-quality PBDP, and any benefit is likely greatest in individuals with hypertension, obesity, elevated cardiometabolic risk, or high baseline SOS intake.

Plant-based dietary patterns are typically discussed in terms of nutrients of concern—iron, creatine, indispensable amino acids, and rapidly fermented carbohydrates—based on the assumption that reduced dietary exposure necessarily translates into reduced physiological availability. This review examines physiological adaptation as an alternative framework, drawing on human intervention and observational evidence across five biological systems: iron homeostasis, endogenous biosynthesis of creatine and carnosine, protein metabolism, fermentation of dietary fiber by the gut microbiota, and the microbial biotransformation of plant polyphenols. Sustained changes in dietary exposure are accompanied by coordinated homeostatic responses, including increased intestinal iron absorption, upregulated endogenous synthesis, improved nitrogen economy, functional remodeling of the gut microbiota, and enhanced polyphenol biotransformation, which contribute to maintaining physiological function. However, adaptive capacity is not unlimited: pregnancy, chronic inflammation, malabsorptive disease, and severe or prolonged dietary insufficiency can exceed adaptive capacity and increase the physiological relevance of dietary intake, planning, or supplementation. Recognizing physiological adaptation as a distinct, measurable phenomenon reframes plant-based diets less as inherently deficient patterns requiring correction and more as a physiological model for understanding how the human body responds to sustained dietary change, with implications for interpreting acute versus long-term evidence and for nutritional counseling.