A revised version of an influential recommended diet which first made waves in 2019 remains "problematic" in terms of meeting human nutritional needs, according to one expert.

The so-called Planetary Heath Diet was developed by the EAT-Lancet Commission, a partnership between the influential medical journal The Lancet and the EAT Forum, which describes itself as a science-based platform for food system transformation.

This diet hit headlines in 2019 for advocating for drastic cuts to consumption of meat and dairy products, and large increases in consumption of plant-sourced foods.

It was lauded by environmental groups as a pathway to reducing the environmental footprint of agriculture, though some in the medical community harboured concerns about nutritional deficiencies from reducing animal-sourced foods to such a large extent.

The Planetary Health Diet was revamped and published again late in 2025 with somewhat less fanfare than its original 2019 version.

But did the latest version account for the concerns that have been raised since 2019 about the possibility of nutritional deficiencies?

According to one of the original diet's critics, seemingly not.

Speaking to Agriland, Prof. Alice Stanton of the Royal College of Surgeons in Ireland (RCSI) said that the actual diet has changed "very little".

"It’s the same basically. There is some rounding up and rounding down of the number of grams that your allowed. It is...much more clearly stated the restrictions on animal-sourced foods, all animal sourced foods," Prof. Stanton said.

"So it's clearly saying that there should only be two relatively small portions a day of animal-sourced foods, one dairy and one from fish, red meat, poultry, and eggs," she added.

These restrictions work out as 250ml of milk or about 25g of cheese from the dairy category per day, and about 75g to 100g from the meat, fish and eggs category per day.

"We know that when average intakes per country drop to 25% to 30% of calories coming from animal-sourced foods, we get increasing micronutrient deficiencies - iron, zinc, iodine, vitamin B12, vitamin D, vitamin A," Prof. Stanton said.

She pointed out that animal-sourced foods are rich sources of those micronutrients, and for some the only source. Potential deficiencies in protein and long-chain omega 3 fatty acids also become an issue in this case as well.

According to Prof. Stanton, the latest version of the Planetary Health Diet is compared more so with usual global diets rather than dietary recommendations.

"What they've done differently in the second version is they’ve said we’re not going to really consider what are the current recommendations for micronutrient intake; we're going to compare it with usual diets worldwide... And they say that actually [it is] equal or better for most nutrients on that basis," she said.

However, Prof. Stanton added: "The current world situation, with current diets, is that over half of the world's population is deficient for at least one micronutrient, and it's not only in poor countries.

"All dietary recommendations are to provide micronutrient adequacy, so to improve the current very poor situation. I can't see how we can recommend a diet that is going to be about the same as the current situation, or perhaps worse for some micronutrients," she added.

Health impacts

Highlighting some of the main health impacts that these nutritional deficiencies can lead to, Prof. Stanton said: "I’d be most concerned about young people, women and the elderly.

"The young people, babies and infants, and growing adolescents, need those nutrients to support growth, particularly of brains, bones and musculature," she said.

"The young and the elderly have increasing protein requirements. It’s difficult to ensure high-quality bioavailable protein from a mainly plant-based diet," she explained.

Prof. Stanton pointed out that, in countries which have, in large, a plant-based diet, they have "a huge instance of childhood stunting...of children who don’t develop physically normally, and whose brains don’t develop normally".

According to Prof. Stanton, it will be "nigh-on impossible to persuade whole populations" to change their diets in ways demanded by the Planetary Health Diet.

"If we don’t realise that this is not going to happen, we’re going to assume it might happen, and we’re not going to spend enough time looking at other ways of addressing the environmental challenges and the sustainability challenges that we face," she said.

2023 Lancet publication

In early 2023, The Lancet published a paper which suggested that the original 2019 diet had several issues along the lines of those described by Prof. Stanton.

However, that 2019 paper doesn't seem to have had a strong influence on the latest version of the Planetary Health Diet from this year.

"The earlier [2019] publication clearly identified that there are differences in bioavailability of micronutrients... In general, nutrients such as iron, zinc, calciun, and vitamin D are more bioavailable and more bioeffective, they are more potent, if they come from meat and dairy, and fish," Prof. Stanton explained.

She added that the 2023 paper "also addressed the presence of antinutrients, including phytate in plant foods, particularly legumes and nuts, which bind-up those micronutrients, which prevent them from being absorbed".

Despite serious reservations over the nutritional deficiencies in the Planetary Health Diet, Prof. Stanton said there is "some value" in what the EAT-Lancet Commission is doing.

She said: "It's part of the discussion, so even though I see the diet as being nutritionally inadequate and impossible to implement in individual countries, and certainly worldwide, I can see that it is a voice that we should listen to."

However, she said that improving the quality of human diets while also reducing the environmental footprint of food production is "a very complex issue, and isn’t solved by a diet from on-high being enforced upon people".