Nutrient Intake and Status in Adults Consuming Plant-Based Diets Compared to Meat-Eaters: A Systematic Review

FAB RESEARCH COMMENT:

This systematic review of 141 studies of micronutrient status in adults following omnivorous, vegetarian and vegan diets found that nutrient deficiencies were common for all these self-reported dietary patterns - but that vegetarians, and particularly vegans, were more likely to show deficiencies in many key nutrients known to be essential for healthy brain development and function.

These included vitamin B12, vitamin D, iron, zinc, iodine and calcium - but also the long chain omega-3 fatty acids EPA and DHA. Deficiencies of these vital fats are almost inevitable in unsupplemented vegan diets, as fish and seafood (or 'organ meats') are the main dietary sources.
However, these brain-essential fats are only mentioned briefly in this news article - and are not included in the overall summary of deficiencies more common in 'plant-based' diets - probably because many studies of 'micronutrients' only include vitamins and essential minerals. 

So-called 'plant-based' diets are widely promoted as having benefits for health as well as the environment - and this review concludes by repeating this as though it were an established fact - which it is not.

The simplistic claim that 'plant-based' diets are 'healthier' and 'more sustainable or 'environmentally friendly' than 'omnivorous ones' - when the term 'plant based' is being used to promote specifically vegetarian or vegan diets - is simply NOT evidence-based, as it fails to take into account two crucial facts.

1) 'Plant-based' is NOT the same as vegetarian (excluding meat and fish) - let alone vegan (excluding ALL animal derived foods - i.e. meat, fish, eggs, milk and dairy products). 

Most traditional human diets have been 'plant-based' - but ALL (before industiralisation) have always included at least SOME animal derived foods, because strictly plant-pased (i.e. vegan) diets simply cannot support human suvival, let alone fertility, healthy reproduction and brain growth without supplementation, or the use of fortified foods.  

With respect to health, as this systematic review itself shows, vegan and vegetarian diets compared with omnivorous ones provide signficantly lower anounts of many key nutrients that are absolutely essential for brain and body health - including the long-chain omega-3 fats (EPA and DHA), vitamin B12, vitamin D, iron, zinc, iodine, and calcium.

The most commonly cited diet for supporting cardiovascular, metabolic and brain health is the so-called 'Mediterranean-type' diet (originally modelled on the traditional diet of Crete - because the first studies to investigate dietary patterns in relation to health in developed countries found that that the Cretan diet was the one most strongly linked linked to freedom from degenerative diseases.

While any traditional Mediterrean-type diets are 'plant-based' in terms of the proportions of different foods consumed, their defining features incude frequent consumption of fish and seafood, as well as meat, eggs and dairy products. 

Importantly, in all traditional diets, these animal-derived foods are also consumed in fresh or minimally processed form - NOT as the industrially produced, ultra-processed versions most common in modern, western-type diets. 

2) The Environmental effects of food production depend crucially on the actual methods used in every stage of the production, storage, packaging, transport and distribution of that food (including all inputs and ingredients, as well as the energy, labour and capital costs involved).

Again - fish and seafood, meat, eggs and dairy products produced via tradtional small, 'mixed farming' methods, are not only highly nutritious, but are also sustainable, and less damaging to the environment than many (but not all) 'plant-based' foods. 

The KEY issue for environmental sustainability is whether foods and their ingredients (plant-derived or animal-derived) - are fresh, whole or minimally processed, and produced locally, using 'regenerative' farming methods (as was the case with almost all pre-industrial diets) - or whether they are produced via large-scale, highly industrialised methods, 

BOTH monocultures of industrially farmed plant crops (such as corn, soy, wheat that dominate modern western-type diets) AND the large-scale 'factory farming' of animals are environmentally damaging.


Related news article:

• Professor warns of micronutrient deficiency risks in sustainable diets