Folic Acid and Vitamin B12

In 1941, a substance extracted from spinach leaves and named folic acid (from the Latin word “folium”) for leaf was found to be effective in the treatment of anemia. Folic acid, also called folate, is a family of water-soluble compounds. The folic acid in diet is converted to its biologically active form in the body with help of vitamin B12 and other vitamins.
     Folic acid participates in several important metabolic processes in the body; the most important being the synthesis of DNA.
     Unlike vitamin B12, which is present only in animal protein, folate are ubiquitous in nature, being present in nearly all natural foods. Again unlike Vitamin B12, folate is highly susceptible to
oxidative destruction: 50 to 95% of the folate content of foods may be destroyed by protracted cooking or other processing (such as canning), and all folate is lost from refined foods. Food with the highest folate content per unit of dry weight include yeast, liver and other organ meat, fresh green vegetables and some fresh fruits.

Recommended Dietary Allowances

Folic Acid
(mcg)

previous
RDA
Folic Acid
(mcg)

1989
RDA
B6
(mg)
B12
(mcg)
Zinc
(mg)
Infants
0 – 0.5 year 30 25 0.3 0.3 5
0.5 – 1 year 34 35 0.6 0.5 5
Children
1 – 3 years 100 50 1.0 0.7 10
4 – 6 years 200 75 1.1 1.0 10
7 – 10 years 300 100 1.4 1.4 10
Males 11 – 14 years 400 150 1.7 2.0 15
Females 11 – 14 years 400 150 1.4 2.0 12
Adults
Males 15+ years 400 200 2.0 2.0 15
Females 15-18 years 400 180 1.5 2.0 12
Females 19+ years 400 180 1.6 2.0 12
Pregnant 800 400 2.2 2.2 15
Lactating, 1st 6 mo 500 260-280 2.1 2.1 19
Lactating, 2nd 6 mo 500 260-280 2.1 2.1 16

The Folic Acid Content of Selected Food

Food Amount Folic Acid (mcg)
Brewer’s (Nutritional) Yeast 1 Tbsp 313
Spinach, raw 1 cup 106
Spinach, cooked 1/2 cup 82
Orange Juice 6 ounces 102
Cereals, fortified (see label) 1/2 cup 50 – 100
Lettuce, romaine 1 cup 98
Lettuce, iceberg 1 cup 0 – 20
Beets, cooked 1/2 cup 66
Avocado 1/2 medium 59
Broccoli, cooked 1/2 cup 44
Wheatgerm 2 Tbsp 40
Beans, red, cooked 1/2 cup 34
Banana 1 medium 33
Brussels sprout, cooked 1/2 cup 28
Bread, whole wheat 1 slice 16
Bread, white 1 slice 10

The Vitamin B12 Content of Selected Food

Food Amount Vitamin B12 (mcg)
Clams, canned 3 ounces 68.0
Oysters, canned 1/2 cup 19.1
Tuna 3 1/2 ounces 18.0
Yogurt 1 cup 1.06
Milk, non-fat 1 cup 0.95
Halibut 3 ounces 0.85
Egg 1 large 0.77
Chicken 3 ounces 0.36
Cheese, Cheddar 1 ounce 0.32