RECENT research indicates that the first potatoes were cultivated near Lake Titicaca, on the Peru/Bolivia border in the Andes, about 8,000 years ago. The potato belongs to the Solanaceae or nightshade family whose other members include tomatoes, eggplants, peppers, and tomatillos. A potato is the swollen portion of the underground stem, which is called a tuber and is designed to provide food for the green leafy portion of the plant.

The potato has been consumed in the Andes for about 8,000 years. Taken by the Spanish to Europe in the 16th century, it quickly spread across the globe: today potatoes are grown on an estimated 195,000 sq. km. of farmland, from China's Yunnan plateau and the subtropical lowlands of India and Bangladesh, to Java's equatorial highlands and the steppes of the Ukraine.

In terms of quantity harvested, the humble potato tuber is the world's No. 4 food crop after maize, wheat, and rice, with production in 2007 of more than 320 million tons. More than half of that total was harvested in developing countries.

Though the tuber was productive and hardy, the Spanish put it to very limited use. In the Spanish colonies potatoes were considered food for the lower classes; when brought to the Old World they were used primarily to feed hospital inmates.

It took three decades for the potato to spread to the rest of Europe. Even so, it was cultivated primarily as a curiosity by amateur botanists. Resistance was due to ingrained eating habits, and the tuber's reputation as a food for the underprivileged and, perhaps most importantly, its relationship to poisonous plants.

As time passed, more and more of the nutritional values of the potato were revealed. Soon, the potato gained wide acceptance across Europe, and Irish farmers became almost totally dependent on it for their livelihood.

The terrible potato disease, caused by the fungus phytophthora infestans, caused a disastrous blight in Ireland in the 1840s. Known as the Potato Famine in Ireland, it cut the population by half (through both starvation and emigration). Potato eventually made its way back over the Atlantic to North America. As time passed, the potato became one of the major foods of the world.



Potato production
The world potato production scenario has been undergoing rapid changes in the last decades. Until the early 1990s, most potatoes were grown and consumed in Europe, North America, and countries of the former Soviet Union.

After that, there has been a dramatic increase in potato production and demand in Asia, Africa and Latin America, where output rose from less than 30 million tons in the early 1960s to more than 165 million tons in 2007.

Data shows that in 2005, for the first time, the developing world's potato production exceeded that of the developed world. China is now the biggest potato producer, and almost a third of all potatoes are harvested in China and India. In 2007, potato farmers produced more than 320 million tons.

In Bangladesh, production of potato was almost stagnant since the seventies until 1998-99, when the production began to increase. In the 10 years between 1999 and 2008, Bangladesh's potato production increased 5 times, with an estimated production of more than 80 lakh tons this year.



Nutrition in potato
Potato has a number of nutritional specialties that are good for health and wellbeing. Most significant of these are its relative richness in calories, vitamin C and potassium. A fresh potato tuber, which is more than 72 percent water, contains, per 100g weight, about 100 kcal, 2.3g protein, 30mg vitamin C (freshly harvested) and 418mg potassium. It contains significant amounts of other vitamins (e.g. niacin) and minerals (e.g. magnesium, zinc), but is very low in sodium. The starch from which the calories come is easily digestible, like that of well cooked rice, and is, thus, very helpful for quick energy supply.

Although low in quantity on fresh weight basis, the protein in potatoes is of high quality, with the essential amino-acid composition comparable to that of egg and milk and better than the proteins of rice and lentils. The maize protein is one of the worst in quality. Indeed, a six-ounce potato (170g) contains 3 grams of high quality protein, almost as much as half a glass of milk.

The high potassium and low sodium in potato makes the tuber an ideal food for people suffering from hypertension. Potassium is also essential for attaining optimal muscle performance and improving the nerves' response to stimulation. Since vitamin C is very unstable, the original content of 30mg may go down to only 8mg after storage of 9 months. The vitamin is also lost if cooking takes a long time.

Cooking potatoes unpeeled conserves most of the vitamin B and C, and the salts. Peeling a potato and cutting it into pieces before it is boiled reduces its vitamin content considerably. If cooked potatoes are reheated there is a further loss of vitamins.

A potato with the skin on is an excellent source of fibre. Instead of throwing away the potato peel, it is better to eat it, because it is rich in mineral elements. At least 60 per cent of the potassium contained in the potato lies so close to the skin that it cannot be saved if the potato is peeled.



Policy implications
The potato should be a major component in policy strategies aimed at providing nutritious food for all, rich and poor alike. As it is ideally suited to places where land is limited and labour is abundant, conditions that characterise many of the developing countries like Bangladesh, potato should be a crop of choice in these countries.

Indeed, potato produces more nutritious food more quickly, on less land, and in harsher climates than any other major crop.

Time series data of the Bangladesh Bureau of Statistics (BBS) shows that in Bangladesh, between 1991 and 2005, consumption of rice decreased by 30g per capita per day while consumption of potato increased by about by 20 gm (see figure below).

During this period, consumption of other food items like meat, egg, fruit, and vegetable also increased somewhat, indicating a positive move towards dietary diversification, slow though it is, in commensuration with economic growth and poverty reduction that have been achieved in the country.

Given the present domestic and international rice market situation, and also considering the high potential for potato production in the country, we can easily turn our attention somewhat more towards the "humble" crop which gives us so much of nutrition and health benefits. We can possibly increase our potato consumption from 60g to 120g a day very easily and make it a part of our daily diet as rice is.

Over the next two decades, the population of Bangladesh is expected to double, where pressure on land and water is already intense. A key challenge facing the government is, therefore, to ensure food security for the people, particularly the poor.

The potato will be an important part of efforts to meet this challenge. Let's make the United Nations International Year of the Potato 2008 a success.

Harun K.M. Yusuf, PhD, FBAS, is Professor of Biochemistry and Human Nutrition, University of Dhaka, and Nutrition Advisor, FAO-National Food Policy Capacity Strengthening Programme (NFPCSP).