Food and Behaviour Research

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

Neufingerl N, Eilander A (2021) Nutrients Dec 23;14(1):29 doi: 10.3390/nu14010029 

Web URL: Read this on PubMed

Abstract:

Health authorities increasingly recommend a more plant-based diet, rich in fruits, vegetables, pulses, whole grains and nuts, low in red meat and moderate in dairy, eggs, poultry and fish which will be beneficial for both health and the environment.

A systematic review of observational and intervention studies published between 2000 and January 2020 was conducted to assess nutrient intake and status in adult populations consuming plant-based diets (mainly vegetarian and vegan) with that of meat-eaters.

Mean intake of nutrients were calculated and benchmarked to dietary reference values. For micronutrient status, mean concentrations of biomarkers were calculated and compared across diet groups.

A total of 141 studies were included, mostly from Europe, South/East Asia, and North America.

Protein intake was lower in people following plant-based diets compared to meat-eaters, but well within recommended intake levels.

While fiber, polyunsaturated fatty acids (PUFA), folate, vitamin C, E and magnesium intake was higher, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intake was lower in vegetarians and vegans as compared to meat-eaters.

Intake and status of vitamin B12, vitamin D, iron, zinc, iodine, calcium and bone turnover markers were generally lower in plant-based dietary patterns compared to meat-eaters.

Vegans had the lowest vitamin B12, calcium and iodine intake, and also lower iodine status and lower bone mineral density.

Meat-eaters were at risk of inadequate intakes of fiber, PUFA, α-linolenic acid (ALA), folate, vitamin D, E, calcium and magnesium.

There were nutrient inadequacies across all dietary patterns, including vegan, vegetarian and meat-based diets.

As plant-based diets are generally better for health and the environment, public health strategies should facilitate the transition to a balanced diet with more diverse nutrient-dense plant foods through consumer education, food fortification and possibly supplementation.

FAB RESEARCH COMMENT:

This systematic review of 141 studies found that compared with omnivores, adults consuming vegetarian and vegan diets were significantly more likely to show multiple essential nutrient deficiencies. 

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 established fact - which it is not. This simplistic claim 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 have always included at least some animal derived foods, because strictly plant-pased (vegan) diets simply cannot support human suvival, let alone fertility, healthy reproduction and brain growth.  

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 on the 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 rather than large-scale, highly industrialised 'factory farming' methods, are not only highly nutritious, but are also sustainable, and less damaging to the environment.


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