Discovering nutrition

The twentieth century is living under the impact of the biological revolution which began a hundred and fifty years ago, when men like Darwin, Wallace, Mendel and Pasteur began to publish their observations on the living world. Their work caused a vast expansion in man’s appreciation of a wide range of biological concepts and systems. It is perhaps surprising that it has taken mankind so long to elucidate the effect of food on health, but without the initial understanding of normal biological processes, the whole subject of health and illness remained shrouded in mystery.

Eat to live

One of the characteristics of a living organism is that it must feed to survive. Animals are specialized organisms, as they cannot meet their food requirements from elemental sources or derive benefit from energy supplied by the sun. Animals have to ingest organic molecules which have been synthesized by other organisms. These molecules are broken down by the process of digestion into smaller subunits which the animal rebuilds into its own typical cellular material. The pieces left over are excreted. These essential unsynthesizable food units, without which the animals cannot survive, became known as nutrients and the study of man and his food is called nutrition.

Vital amines

Although the science of nutrition has only recently been recognized, populations have developed traditional methods of food preparation that have contributed to an adequate nutrient intake. The Central American Indians learnt to add alkali to their tortilla dough so as to release a bound vitamin in the corn.

Despite such methods, diseases of nutritional origin have occurred over the centuries. Rickets caused by vitamin D deficiency was described in ancient times and in the Middle Ages. Scurvy also afflicted sailors until Lind in 1753 published his famous treatise based on tests with citrus fruits which relieved symptoms. British sailors became known as “limeys” because of their ration of lime juice containing vitamin C.

In 1883 Takaki eliminated beriberi as a cause of death in the Japanese army by feeding the men bread, vegetables and milk instead of milled rice. Similarly Eijkman in 1890 found his chickens thrived on unmilled rice and postulated that there was a substance present in the germ or pericarp of the rice without which health was impaired. This suggestion was quite new and innovatory, as it was thought that germs caused illhealth. For this inspired work Eijkman was awarded a Nobel Prize.

The turn of the century produced a flourishing investigation into these accessory factors, as they came to be known. The term vitamin was derived from the latin for vital amine – but is a misnomer as they are not all amines.

Sir Frederick Gowland Hopkins, McCollum and Davies, and Sir Edward Mellanby were responsible for describing the vitamins A, B and D respectively; their chemical isolation and synthesis soon followed. Research continues, as there is still controversy about metabolism and the bodily requirements of many vitamins like C, E, and K.