Chris Voigt, executive director of the Washington State Potato Commission, has completed a two-month stunt, organised to prove the potato's nutritional value, as a protest against efforts by dietary busybodies to limit the use of it in US government food programs.

The bossy boots in the Women, Infant and Children's Program run by the US Department of Agriculture, which provides food to low-income women and children, changed the rules to exclude the spud from the handouts of fruit and vegetables.

His stunt consisted of eating 20 spuds a day - 1200 in all over 60 days - and nothing else. Not even toppings - cream, sour cream, chile, bacon bits or any of the myriad ways by which the potato is prepared and, these days, sometimes turned into a metabolic catastrophe, particularly in the US.

At most he used a little salt, pepper and oil - and apparently, sometimes some herbs - with which to fry (but not deep fry), bake, boil, mash or place in ashes the spuds.

It seemed to do him no great harm, even if he was longing for a little variety by the end.

Old Ireland was divided into those who could afford to put other things on their tables (or on their potatoes) and those for whom the ''sauce of the poor man'' was a little potato on top of a big one.

Mr Voigt chose 20 spuds a day so as to maintain his weight, based on a calculation of his height, body mass index and what is known of the food quality of potatoes. The diet saw him shed 10 kilograms, and caused his body mass index to fall from a plump (but hardly obese) 26 to a very satisfactory 23. The diet also caused a significant fall in his cholesterol, triglycerides, low-density lipoprotein and dramatic falls in the ratios of cholesterol over high-density lipoprotein (a fall of 37 per cent). There was also a significant (9 per cent) fall in his blood sugars.

One could say this produced a dramatic reduction in his risk of diabetes or heart disease.

No one - not even Mr Voigt - argues that the spud is a complete food, but it does a better imitation of it than most foods, including most other vegetables. Ireland's love-hate relationship with the spud came from a massive over-dependence on the tuber, which was to prove catastrophic when the crop was ruined by blight during the 1840s. Yet the misery and the starvation - and the massive emigration it forced - would not have been necessary had the English landlords, and the English government, not closed their minds and hearts to the problem, in an early rendition of Jenny Macklin's tough love program for Aborigines, single mothers and students.

Irish exports of beef, wheat, pork and dairy produce to Britain (and, by and large, the standard of living of the Irish landlord class) were not greatly affected by the famine. Indeed, to a good extent, it was regarded as God's judgment on the feckless Irish, both for being fond of the spud in the first place, and for becoming dependent upon it.

There were several aspects to this. First, the spud was of South American origin and, therefore, weird and somewhat sinister. It had weird South American cousins - the tomato, the capsicum, the eggplant and even the tobacco plant are fairly closely related to the potato, but these at least produced their fruit above the ground, not in the soil. Its European relations - mandrake and deadly nightshade, for example - were definitely sinister, dangerous and used by witches and wizards. Like tobacco, it could induce narcosis, which seemed to confirm intrinsic danger.

As well as this, the spud had several initially mysterious attributes. It would, for example, flourish above the ground, and produce stems, leaves and flowers without doing a thing down below. Indeed, there seemed very little relationship between what was going on below and on top. It took a long time for people to twig that the tuber-growing process was triggered only when there was about 12 hours of sunshine a day.

Spaniards, Italians, the French, and even Scots and Poms did not entirely loathe the spud, and France even invented the french fry, but all of them regarded it as essentially a garden rather than a paddock vegetable, so that the crop was small and exotic, not one, for a long time, enjoyed by the common herd.

It was, more or less, the Irish who recognised how easy it was to plant in profusion in an open field, so that an acre or two could feed whole families all year. One did not even need a plough, anything much in the way of agricultural implements, soil preparation, processes of raking, hoeing, harrowing or harvesting, or anything too complicated in terms of storage of the product.

The lazy bed system involved not much more than creating dirt ridges separated by trenches. One buried the ear of a spud, or the seed potato, inside the ridge, and that was pretty much it. A typical yield was about 10 tons of spuds to the acre from, probably, an aggregate of 20 days work in a year.

And the spud, once grown, could be eaten without any processing. The previous cereals of Ireland, oats and, to a lesser extent, wheat required milling or grinding; a spud could be boiled in a kettle or baked in the ashes of a peat fire. A child could cook one as well as an adult.

Stored underground, or away from the sun, the potato would keep. Even if it came to be affected by sunlight, so that the skin turned a sinister (and dangerous) green, the problem could be averted simply by peeling.

Some say that Walter Raleigh (the Wessex colonialist who, had he been able to spell properly, would have been called Walter Riley) brought the tuber to Ireland, where he had a farm.

In any event, no country in Europe was as suited to the profusion of the spud. This was, according to Larry Zuckerman's historical account The Potato, primarily because Ireland sat so comfortably alongside the Gulf Stream and, as a result, enjoyed a mild, if wet, climate. Lots of 12 hour days, too.

But all of this convenience was, perversely, at the heart of Protestant disapproval.

Protestant ideology was developing the notion of a relationship between hard work and virtue, between effort and reward, between wealth, its creation, the work ethic and the favour of God.

It was a puritan, disapproving code of beliefs which suited the northern European climes where Protestantism flourished.

By contrast, in the more Mediterranean environments such as Spain, Italy and Ireland, Protestantism never took hold, and, even today, the Germans and the Scandinavians believe that the collapse of European Community economies has been in the feckless and Catholic south, rather than among the industrious northerners.

Even socialism has had a Protestant face, via Methodism. In Australian labour circles, the influence of the Methodist strain has been balanced by the Irish element, at least until the advent of ''up-by-the clock'' Julia Gillard and that natural-born straightener and anti-fun person Macklin.

''Natural'' farming - with wheat, oats or other grains - involved a year-round cycle of soil preparation, rotation, sowing, weeding, harvesting and post-production. In the more northern parts, questions of winter food storage were important because of snow and ice on the ground. By contrast, in Ireland, it rarely snowed.

A very hard-working farming family, particularly in the years preceding the Agricultural Revolution, was barely able to survive with everyone working 10 hours a day. If meat was part of the diet, it was only obtained by trading bread or wheat.

This was, the ruling ideology went, more or less ordained by God. As punishment for Adam and Eve, God had told Eve that she would have pain in childbirth, and Adam that he was condemned to work. The ground would be cursed, would bring forth thorns and thistles, and that in sorrow and in sweat would man work to get bread.

What a slap in the face - whether to God or to hard-working Scots, Germans, Welsh or Englishmen - that the Catholic Irish were growing an equally nutritious crop with scarcely a stroke of work.

What was worse was that this idle and feckless existence, once established, seemed only to accentuate their already deplorable habit of breeding.

A culture of dependency - far worse than that inflicted on Aborigines by sit-down money - was being instilled, not to mention a habit of cheek and insolence to their landlords and betters. Anyone who reads the sectarian literature of the 19th century, or Methodist literature about the risk of pandering to the poor, will appreciate that the Irish were hardly seen as human - and of a lower standard of citizenship than the modern Aborigine.

Accordingly, the development of a blight on an increasingly mono-cropping population was seen as a judgment of God on the benighted Irish. Basically, they had it coming.

Before the spud, the Irish had a more varied diet, though hardly an exciting one. Like the Scots they ate a lot of oats, which in England was mostly for horses. They had lots of dairy, particularly curds and whey, and the richer ones had pigs and chickens.

Increasingly, however, the poor became more dependent on the spud, often seeing it as a real treat, sometimes mixing it with milk, butter, turnips, cabbage or onions. Once the blight came it seemed as if the laws of supply and demand were turned on their head: the less money people had, and the pricier an undiseased potato became, the higher the demand. In due course, the diaspora Irish flourished in a land where there was more opportunity.

It was, however, a lesson in over-dependence on one type of food, not a judgment on the spud; just as Mr Voigt's survival and triumph is one up on the fun police, with whom Australians are all too familiar.