There is general agreement amongst health professionals and dieticians
that manganese is essential to ensure the health and well being of humans and
animals. The human body contains from 12 to 20 milligrams of manganese.
Estimations of the human requirements for manganese vary considerably, but are
based on studies of the balance between intake and excretion necessary to
maintain this level.
Data from several studies suggest that manganese intake of from 0.035 to
0.070 milligrams per kilo of body weight provides the needed balance. However,
a 1988 study conducted by researchers at the University of Texas at Austin
found that a minimum of 3.5 milligrams per day seems necessary.
Human consumption depends on the amount of certain foods consumed. The
typical English winter diet (with substantial tea intake) provides up to 8.8 mg
of manganese per day, while studies of women in Japan, Canada, New Zealand and
the USA suggest average daily intakes from 2.5 to 4 mg per day.
Manganese deficiency has been demonstrated in animals and has been noted
in humans in association with vitamin K deficiency. Its main manifestations in
all species studied are impaired growth, skeletal abnormalities, disturbed or
depressed reproductive functions, lack of muscular coordination among newborns
and defects in lipid and carbohydrate metabolisms.
The following fresh food groups (in descending order) are most important
in manganese content: nuts, whole cereals, dried fruits, roots, tubers and
stalks, fruits, non-leafy vegetables, meat, poultry products, fish and
seafoods. Leafy vegetables also rank high on the list when expressed in
dry-weight terms. Tea has a very high manganese content, ten times that of
The wide range of manganese contained in cereal grains and products
depends on the species and on the milling process used. In a US study,
wholewheat containing 31 ppm total manganese yielded 160 ppm in the germ, 119 ppm in
the bran and only 5 ppm in the white flour.
Half a cup of oatmeal, 30 grams of shredded wheat or raisin bran cereal,
a quarter of a cup of pecans or a third of a cup of peanuts, and half a cup of
cooked spinach, contain each over a milligram of manganese.
Sweet potatoes, red lima or navy beans and pineapple juice are other
sources. There is very little or no manganese present in dairy products and
highly refined sugar-containing foods.