Addressing the Question of Nutritional Equivalence in Future Foods

There is no denying that our food supply chain is a system under stress with our ever-expanding population, compounded by a changing climate that’s squeezing producers to maximize production under increasingly challenging circumstances. And then there’s the environmental impact that agriculture itself is having, with livestock rearing fingered as a significant contributor, feeding back into a cyclical problem. It is therefore no wonder that the research into and appetite for alternative protein sources has exploded in the last few years. Multiple avenues are being explored, some more novel and ambitious than others, including microbial fermentation, cellular agriculture, mycoproteins, insects, algae and plant-based proteins.

While the likes of cellular agriculture are still providing the consumer with animal cells and the nutritional value they convey, the same cannot necessarily be said for their plant-based counterparts.

The labeling illusion

Look at most food packaging and it will provide you with a breakdown of the nutritional values of that product. However, how many of us really understand what we are being shown or what’s being hidden? While nutritional breakdowns may give us an idea of the number of grams of saturated fat something contains or its calorific value, we are only seeing part of the picture. Labels generally state the protein content grouped together as a single entity, but proteins are made up of amino acids, the composition of which can vary greatly from protein to protein. This fact is vitally important when we consider our dietary needs. While our bodies are able to synthesize some amino acids, others must be ingested in the food we eat, hence it is important that we include protein sources rich in these missing “essential amino acids” in our diet. But looking at most packaging, it is not possible to tell whether the amino acids obtained from a plant-based burger, for example, are equivalent to those we could obtain from eating its meat-based counterpart.

The amino acid make-up is not the only aspect that may vary either.¹ Digestibility, a factor impacted by how the building blocks of molecules are put together in those foods, can have a great impact on what we can or cannot obtain from it. The presence of so called “antinutrients”, such as phytic acid, present in some legumes used as a popular meat substitute, can also reduce the bioavailability of nutrients and compounds present. So, what may superficially appear “the same”, has the potential to mask important differences in nutritional values. A 2019 consumer survey conducted by the International Food Information Council highlighted how presenting nutritional information in this way can impact consumer attitudes and opinions towards foods that will inevitably influence their food choices.

Are plant-based foods nutritionally equivalent to animal products?

In short, the answer to this question is no. However, that’s not to say meat = good, plants = bad, there are wins and losses on both sides.

A 2021 study by Dr. Stephan van Vliet and colleagues at Duke University School of Medicine, published in Science Reports,² highlighted some of these discrepancies at the metabolic level. The team used untargeted metabolomics to explore the metabolite profiles of grass-fed ground beef and a popular plant-based alternative that had been matched for serving size and fat content. While the nutritional labeling on the products appeared very similar, their analyses revealed around a 90% difference in metabolite profile between the foods that spanned the nutrient classes, including amino acids, fatty acids, vitamins and phenols. Teasing these results apart showed that 22 metabolites were found exclusively in the beef and a further 51 were in greater quantities in the beef than the plant-based alternative. However, 31 metabolites were found exclusively in the plant-based alternative and a further 67 were in greater quantities than in the beef product. While the beef provided compounds such as glucosamine, which benefits connective tissues and blood vessels, and antioxidants including squalene that the plant-based product lacked, the plant-based alternative provided vitamin C and phenolic antioxidants among other beneficial molecules that were absent in the beef.

The study gives us a taste of just how different these apparently similar foods are and the problem with routinely tracking (around 150 in the case of many databases) and reporting (around 13 in the case of most nutritional information labels) only a fraction of the nutritional components and/or grouping them together. This also highlights that studies based on label or categorization information³ rather than more comprehensive analytical data may miss important shortcomings and benefits of both animal products and their alternatives.

The authors concluded from their results that, on this basis, the products shouldn’t be viewed as interchangeable but instead as complementary to one another from a nutritional standpoint. They write, “The complexity of the whole food matrix—as indicated here by our metabolomics findings—highlights that attempting to mimic food sources using single constituents such as isolated proteins, vitamins and minerals is challenging and arguably underestimates the complexity of the food source it is meant to mimic.”

This echoes evidence from other groups that protein sources are not metabolically or nutritionally equivalent,^{4, 5} with De Marchi and colleagues finding 21-fold less methionine—an essential amino acid for humans—in plant-based compared to beef burgers.⁶ They concluded that complete and unbiased nutritional information on such products is necessary so that consumers can adjust their diet accordingly to continue to meet their nutritional needs. Since then, further studies have gone on to add to this body of evidence, look for alternative sources that do deliver high-quality protein⁷ and ways to bridge the gap.

A need for guidance

A number of studies have also highlighted nutritional disparities of animal, traditional plant-based and novel plant-based foods that may be visible on nutritional labels but to which many of us may pay little attention based on our preconceptions about plant-based alternatives compared to their animal-based counterparts. In a bid to enhance the sensory appeal of novel alternative proteins over some traditional plant-based substitutes,⁸ some products have turned to the addition of salt, sugar and fat and are themselves classed as ultra-processed foods.⁹

A 2021 study from Tso and Forde found that while a diet of traditional plant-based substitutes met daily requirements for calcium, potassium, magnesium, phosphorus, zinc, iron and Vitamin B12 and was lower in saturated fat, sodium and sugar than the reference omnivorous diet, diets based on novel plant-based substitutes failed to meet daily requirements for calcium, potassium, magnesium, zinc and Vitamin B12 and exceeded the reference diet for saturated fat, sodium and sugar.⁸

A 2022 study from researchers at the University of Göttingen highlighted the differences in nutritional values for both meat and cheese against their plant-based alternatives using nutritional scoring and analytical chemistry-based techniques to evaluate vitamin and mineral content.¹⁰ The work highlighted that fat, saturated fatty acids and salt in particular varied considerably between the samples tested. While some of these differences may be visible on nutritional labels, the authors suggested that because of these types of differences, “consumers need guidance on how to compose a balanced plant-based diet.” This message is reinforced by a UK study highlighting the high level of salt in five out of six plant-based meat alternatives tested, with three quarters not meeting UK salt intake guidelines.¹¹

In Canada, legislation has been introduced this year stipulating criteria for the protein content, protein quality and minimum content of a range of vitamins and minerals permitted in meat alternatives to try and help address some of these concerns.

Filling the gap

Redressing nutritional inequities, both present and absent from nutritional labels, between alternative protein sources and the animal products they are seeking to emulate is understandably an active area for future foods research. Enhancing the micronutrient profile while reducing reliance on nutritionally sensitive components such as salt and sugar are of particular interest.

Fortification is one method by which missing components may be added to meat alternatives. Vitamin B12 is a good example, being important to health but typically absent or only present in unavailable forms in plants. However, adding individual components without the complex matrix in which they are found in the original meat product may mean that synergistic benefits gained from meat consumption will still be impaired.¹²

Genes may be engineered in that enhance the capabilities of plants or cells to produce these missing nutrients. This approach has been utilized successfully to enhance the nutritional value of bovine cells used to produce cell-cultured meat. However, in this particular case, the scientists sought to provide added nutritional benefits that would not normally be present in the original meat product rather than add back in something that was missing.

Even if a nutrient is present in both the meat and alternate protein source on analysis, that does not necessarily mean that its bioavailability is the same in both foodstuffs.¹³ Take iron for example. In meat, iron is present in heme, which has greater bioavailability than the non-heme form found in plants such as legumes that provide popular meat alternatives. To address this, scientists have developed a novel plant-based alternate protein source in which the iron is present in the heme form thanks to a soy leghemoglobin protein preparation derived from Pichia pastoris yeast.¹⁴ However, while encouraging, this is far from standard practice in foods we are likely to find on supermarket shelves.

Food for thought

While recent innovation in the alternative protein source space has seen great improvements in organoleptic properties such as texture, taste and appearance, it would appear that there is still much to be done to address nutritional inequalities.¹⁵ The general message seems to be that alternative protein sources, especially those derived from plants, can provide a more sustainable alternative to animal products but currently there is a significant degree of nutritional variability within the field. Consequently, it is important that consumers do not see many of these products as a straight swap or consider only the protein quantity of the product,¹⁶ with a more flexitarian approach to their consumption advised by some.¹⁷ At risk groups such as children, pregnant women and the elderly need to be particularly careful and improvements in regulation and legislation standards could help to safeguard shoppers.