Manufacturers of plant-based meat substitutes have worked hard to produce a taste and mouth-feel that is comparable to their animal-based counterparts. The texture of meat analogues is thickened with indigestible fibres, like methyl cellulose. While leghemoglobin, an iron carrying molecule extracted from soy, red beet berries and carrot extracts have been used to simulate ‘bloodiness’.
The nutritional labels of plant-based analogues, calling out vitamin, fat and protein content, might also suggest some degree of equivalency. In order to increase the protein levels of plant-based meat alternatives, for instance, isolated plant proteins from soy, peas and other plant-based sources are utilised. Some formulations also include the addition of vitamin B12 and zinc to their recipes in order to simulate meat’s nutritional profile.
However, a new study from researchers at Duke University notes that many other components of nutrition don’t appear on product labels – and this is where they say plant-based analogues ‘differ widely’ from meat alternatives.
The research, published this week in journal Scientific Reports, measured metabolites – the ‘building blocks of the body's biochemistry’. The study’s authors note that these metabolites are crucial to the conversion of energy, signalling between cells, building structures and tearing them down, and a host of other functions.
There are expected to be more than 100,000 of these molecules in biology and about half of the metabolites circulating in human blood are estimated to be derived from our diets.
"To consumers reading nutritional labels, they may appear nutritionally interchangeable," said Stephan van Vliet, a postdoctoral researcher at the Duke Molecular Physiology Institute who led the research. "But if you peek behind the curtain using metabolomics and look at expanded nutritional profiles, we found that there are large differences between meat and a plant-based meat alternative."
Meat and plant-based: Not a like-for-like substitution
The Duke Molecular Physiology Institute's metabolomics core lab compared 18 samples of a popular plant-based meat alternative to 18 grass-fed ground beef samples from a ranch in Idaho. The analysis of 36 cooked patties found that 171 out of the 190 metabolites they measured varied between beef and the plant-based meat substitute.
The beef contained 22 metabolites that the plant substitute did not. The plant-based substitute contained 31 metabolites that meat did not. The greatest distinctions occurred in amino acids, dipeptides, vitamins, phenols, and types of saturated and unsaturated fatty acids found in these products.
The researchers found several metabolites known to be important to human health were found either exclusively or in greater quantities in beef. This included: creatine, spermine, anserine, cysteamine, glucosamine, squalene, and the omega-3 fatty acid DHA. "These nutrients have potentially important physiological, anti-inflammatory, and or immunomodulatory roles," the authors said in the paper.
Vegans ‘can live healthy lives’
While the research highlighted nutritional deviations between meat analogues and beef, the study authors did not make any conclusions over which option was beneficial for human health.
"These nutrients are important for our brain and other organs including our muscles," van Vliet explained. "But some people on vegan diets can live healthy lives - that's very clear."
Indeed, the researchers stressed that the plant-based meat alternative contained several beneficial metabolites not found in beef, such as phytosterols and phenols.
"It is important for consumers to understand that these products should not be viewed as nutritionally interchangeable, but that's not to say that one is better than the other," van Vliet concluded. "Plant and animal foods can be complementary, because they provide different nutrients."
He said more research is needed to determine whether there are short-term or long-term effects of the presence or absence of particular metabolites in meat and plant-based meat alternatives.
'A metabolomics comparison of plant based meat and grass fed meat indicates large nutritional differences despite comparable Nutrition Facts panels'
Authors: van Vliet, S., Bain, J.R., Muehlbauer, M.J. et al.