Today’s food is different from a few decades ago

The nutrition in fruits and vegetables has significantly dropped in the past few decades, mainly because of the use of pesticides, fertilizers and degrading soil quality.

For instance, a landmark study (2004) of vegetable fruits found that several nutrients, such as vitamin C, iron, calcium etc. have declined across major garden crops since 1950. And this decline has only increased over the past few years.

It simply means natural food sources have less nutritional content, which may not be enough to meet your body's needs.