She made her case earlier this month at the Nutrition Society’s summer conference, explaining that a number of sustainable diets recommend that meat and dairy consumption should be limited to meet greenhouse gas emission goals.
She drew attention to the well-known EAT-lancet dietary recommendations, released in 2019, which focusses on reducing meat, egg, and milk consumption.
“However, earlier this year there was a viewpoint published in the Lancet which identified potential risks of this EAT-Lancet diet in terms of micronutrient deficiency. This is partly concerned with the bioavailability of these micronutrients within a plant-based diet, which hadn’t been completely accounted for. This included vitamin B12, iron and zinc,” she asserted.
She said research conducted at Surrey university had been carried out to identify the iodine provision from the diet, following the lack of its identification as an additional at-risk nutrient in the viewpoint report. She noted this is potentially due to the assumption that people would consume iodised salt; a health programme which has not been implemented in the UK.
It was found that iodine intakes from the diet were lower than the recommended amounts of 150 mcg per day, whilst in those consuming dairy alternatives, intakes were found to be just 54 mcg per day due to the lack of product fortification.
She concluded that guidelines should specify that additional iodine supplementation may be required, whilst calling for the industry to consider iodine fortification in alternative products.
“Unless there was additional supplementation or fortification with iodine, the EAT-lancet diet wouldn’t meet our needs,” she asserted.
Animal vs. plant-based diet
“Animal-based foods provide us with a huge proportion of nutritional requirements and are really important for the provision of micronutrients,” she explained.
She specified that, according to the national diet and nutrition survey, milk and dairy products provide around a third of adult requirements for B12, calcium, and iodine, and around 25% of riboflavin. Meat products contributed 30% of B12 and zinc, and 20% of iron, whilst eggs and fish provided a smaller but still significant source of iodine and B12.
Prof Bath spotlighted the findings of a systematic review involving 141 global studies: “It found that plant-based diets, whether that’s vegan, vegetarian or a mixture, had some benefit in terms of some micronutrients including folate, vitamin C and E. But it did identify that, overall, there were lower intakes and status of vitamins B12 and D, iron, iodine, zinc, and calcium in those following a predominantly plant-based diet.”
She added that these at-risk micronutrients are particularly important for reproductive health in women, particularly prior to and during pregnancy, as well as for the subsequent cognitive health of the child.
Deficiency prevalence
“Micronutrient deficiencies are recognised as a huge global public health concern and is identified as ‘hidden hunger’ with two billion affected by at least one micronutrient deficiency world-wide. It tends to affect mostly women and children, partly due to their higher requirements, but also because they are particularly vulnerable to the effects of deficiency,” she stressed.
She added that in the UK one third of women were deficient in at least one micronutrient, whilst specifically for iodine, 12% of girls aged 11-18 and 10% women 19-64 years old were reported to have intakes below the LRNI (lower reference nutrient intake).
She highlighted that, in addition to intakes of iodine that are already low in the particularly at-risk groups of women and young girls, this group was also more likely to adopt a plant-based diet.