Look at the food label for any grain product (even the most refined of breads) and you’ll always see 4 B-vitamins (thiamin, niacin, riboflavin, folate) and iron listed.
Thiamin(B1), riboflavin (B2), and niacin (B3), are bread's enriched vitamins, while iron is its enriched mineral. Meaning, the flour lost these nutrients while undergoing the milling process, so they are added back in.
The requirement of replenishing these nutrients stems from the Enrichment Act of 1942, an initiative to lower the rates of vitamin and mineral deficiencies at the time.
In February of 1996, the Food & Drug Administration required that folic acid (the bioavailable version of folate, another B vitamin) be added to all grain products,in an effort to lower rates of neural tube defects (research unequivocally demonstrated that babies of women who consumed low levels of folate during the first trimester of pregnancy had a higher risk of being born with neural tube defects.)
Folate is not originally found in the endosperm of grains (which is the only part white bread is made from), so it is put in via fortification (added on), rather than enrichment (added back).
Since folate is a B vitamin (which is water soluble), it is crucial to get the required amount every single day.
Whole grains naturally contain folate, so they do not need extra amounts.
Quick lesson on whole wheat vs. white or regular wheat bread:
• Whole wheat breads use all 3 parts of the wheat shaft: the germ, bran, and endosperm
• Refined wheat breads only use the endosperm (thus completely missing out on nutrients found exclusively in the bran and germ, such as vitamin E and selenium).
Fortunately, the folate initiative has worked! Since the fortification of folate to breads, cereals, and pastas, neural tube defects have decreased by 25 percent in this country.
Why bread products? They are widely consumed by people in the United States, regardless of age, socioeconomic level, or ethnicity.
That being said, commercial breads are not the best sources of folate. Spinach, asparagus, and all sorts of legumes (lentils, chickpeas, black beans, kidney beans, etc.) provide more substantial amounts of this crucial B-vitamin.