Thank you for the stimulating overview on sulfur requirements and the possibility of its widepsread dietary inadequacy.
If I am not mistaken you are in error when you state: "From the standpoint of the diet, methionine alone is capable of providing all the necessary body sulfur, with the exception of the two sulfur-containing vitamins, thiamin and biotin." Pantothenic acid is also a sulfur containing vitamin which cannot be made from methionine in humans, and therefore must be supplied by the diet.
Also there seem to be contradictory statements about the cysteine/methionine ratios found in various foods:-
"In general the ratio of cysteine/methionine is close to one for poultry and red meat protein, and to 0.7 for fish. Dairy products tend to have slightly higher levels of methionine and starch rich foods slightly more cysteine. Eggs contain significantly more cysteine. To estimate molar concentrations a 1:1 ratio was employed."
appears to contradict this:
"In milk and dairy products the methionine/cysteine ratio is around 3/1. It is roughly the same in fishes such as canned tuna, which we used as a source of protein supplement in our studies, and in meats. In eggs, soy beans and other plant products it is around 4/3."
Thank you for an otherwise interesting and important article.
Pantothenic acid is a sulfur containing vitamin
2 July 2010
Thank you for the stimulating overview on sulfur requirements and the possibility of its widepsread dietary inadequacy.
If I am not mistaken you are in error when you state:
"From the standpoint of the diet, methionine alone is capable of providing all the necessary body sulfur, with the exception of the two sulfur-containing vitamins, thiamin and biotin."
Pantothenic acid is also a sulfur containing vitamin which cannot be made from methionine in humans, and therefore must be supplied by the diet.
Also there seem to be contradictory statements about the cysteine/methionine ratios found in various foods:-
"In general the ratio of cysteine/methionine is close to one for poultry and red meat protein, and to 0.7 for fish. Dairy products tend to have slightly higher levels of methionine and starch rich foods slightly more cysteine. Eggs contain significantly more cysteine. To estimate molar concentrations a 1:1 ratio was employed."
appears to contradict this:
"In milk and dairy products the methionine/cysteine ratio is around 3/1. It is roughly the same in fishes such as canned tuna, which we used as a source of protein supplement in our studies, and in meats. In eggs, soy beans and other plant products it is around 4/3."
Thank you for an otherwise interesting and important article.
Competing interests
None