- A Dutch modelling study found that replacing animal foods with plant-based alternatives can reduce protein and several key nutrient intakes.
- Older adults, adolescents and some women appeared most vulnerable to shortfalls.
- The message is not that plant-based diets are unhealthy, but that simple swaps are not always nutritionally equal.
Plant-based eating can be good for health and the planet, but it still needs proper planning.
A Dutch dietary modelling study looked at what happens when commonly eaten animal-based foods are replaced with plant-based alternatives.
Researchers used national dietary data from 3,570 people aged 1 to 79.
They modelled two scenarios.
One used more nutritionally favourable plant-based replacements.
The other used more widely available plant-based substitutes with lower nutritional quality.
This was not a trial of people eating vegan or vegetarian diets in real life.
It was a simulation of partial replacement.
That distinction matters.
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In the original diets, protein intake was generally above standard recommendations for most age groups.
After the substitutions, protein intake fell.
In several adult groups, especially women, intake dropped below recommended levels.
Older adults were a particular concern because they often need more protein to preserve muscle.
Essential amino acid intake also declined.
Most amino acids remained above recommended levels, but methionine plus cysteine fell below recommended levels in older adults in both scenarios.
Several vitamins also dropped after substitution.
These included vitamins A, B1, B2, B3, B6 and B12.
Vitamin D was already low before the dietary shift and stayed inadequate afterwards.
Calcium fell further too, becoming below recommended levels across all groups.
Iron intake rose slightly because of more non-haem iron, but remained low for children and women of reproductive age.
Iodine, selenium and zinc also fell.
Zinc became inadequate across all age groups after substitution.
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That sounds negative, but the right interpretation is more nuanced.
A well-planned plant-based diet can be nutritionally strong.
But swapping meat, fish and dairy gram for gram with whatever plant-based substitute is on the shelf may not deliver the same nutrient profile.
Fortification matters.
So do legumes, nuts, seeds, whole grains, calcium-set tofu, fortified milks and B12 supplementation.
The study is a reminder that plant-based eating should not be treated as automatically healthy by default.
The quality of the replacement matters just as much as what is being removed.
