It formed its conclusions after a literature review and assessment of the amino acids use in foods and food supplements on the Norwegian market but only in free form.
It assessed 30 amino acids.
“Histidine, methionine and tryptophan are essential amino acids, whereas SAM is a metabolite from methionine,” wrote VKM in the report.
“Mild adverse effects such as nausea and reduced appetite were reported with the use of all four amino acids. There are indications that intake of methionine during the so called methionine-loading test (100mg methionine per kg body weight) is associated with adverse health effects such as dizziness, sleepiness and decreased or increased blood pressure.”
“Intake of methionine supplement seems to be a concern for health also because increased concentration of its metabolite homocysteine in plasma may be associated with cardiovascular disease.”
VKM recommended a tentative guidance level (GL) of210mg/day for methionine, and 220mg/day for tryptophan. They said there was not enough data for the other two.
“The intake of these four amino acids in free form was based on the doses used in food supplements sold in Norway, VKM estimates the intake of free form histidine and SAM to be within an acceptable level, whereas the doses of methionine in supplements available at the Norwegian market is higher than the tentative suggested GL in this assessment.”
“According to information from the Norwegian Food Safety Authority, supplements with single free tryptophan are not sold on the Norwegian market.”