Replacing 30 grams of white or oily fish daily with plant-based protein sources is linked to a higher likelihood of vitamin B12 deficiency in adults aged 21 to 75.
Mechanism
Synthesis from 1 study
Fish is one of the few natural sources of vitamin B12 that the body can use. When people replace fish with plant foods like beans or tofu, they stop getting this essential nutrient. Over time, their body runs low on B12 because plants don’t provide it, and without enough, cells can’t function...
Most probable mechanism
When people stop eating fish and eat more plant-based proteins instead, they get less of the form of vitamin B12 that the body can use. This causes the amount of B12 in the blood to drop over time, and cells can't get enough to do their normal jobs, which can lead to deficiency.
Dietary substitution of fish with plant-based proteins reduces intake of bioavailable vitamin B12, which is naturally present in animal-derived foods but absent in unfortified plant foods.
Lower intake leads to a gradual decline in serum cobalamin concentrations due to limited hepatic storage and no compensatory endogenous production.
Reduced serum levels impair the binding and transport of vitamin B12 to peripheral tissues via transcobalamin II, limiting cellular uptake and utilization in metabolic pathways requiring methylcobalamin and adenosylcobalamin.
Evidence from Studies
Supporting (1)
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Substituting animal protein foods with plant protein foods influences vitamin B12 and folate statuses in a multiethnic Asian population
Contradicting (0)
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