Mikkel Hindhede (1862–1945): A pioneering nutritionist

Early life

Mikkel Hindhede (Figure 1) was born on 13 February 1862 in Lem, Denmark. He was the first son of Jens Mikkelsen Hindhede (1835–1919) and Else Marie Oline Christense Fjord (1843–1862).^1,2 Hindhede’s mother died 5 days after his birth and he was brought up by his father and grandmother who were both strong Protestants and Hinhede was, therefore, raised in ‘fear of god and admonition of the Lord.’ His father remarried and had three more children but Hindhede remained mostly under the care of his grandmother. OPEN IN VIEWER

Hindhede idolised his father and described him as the greatest man he had ever known and the man who had the greatest influence on him. His father was a successful farmer who was profitable even in difficult agricultural times due to a strict economy and good business sense. In the first 16 years of Hindhede’s life, his daily diet mainly consisted of rye bread, milk, gruel, porridge, soups, fish or meat, and as many potatoes as he could eat. Hindhede stated that this diet taught him to appreciate a simple way of living, and the high amount of potatoes in particular was something he continued to have in his diet throughout his life.

Hindhede did remarkably well in school and it was said that he was better at maths than his teacher who recommended an academic path for Hindhede instead of farming. Therefore, in 1878 through the financial help of his father he moved to Copenhagen to pursue academic success. Due to Hindhede’s strong mathematical skills, it was anticipated he would make a career as an engineer. However, because of an oversubscription of students to study engineering at the time, he enrolled to the undergraduate medicine course at Copenhagen University in 1881 after finishing his university preparing exams.

Medical school

Hindhede looked forward to experiencing the student life but he became very disappointed with the reality of it. He was repelled by the large alcohol consumption by his fellow students and their liberal-minded relation to girls and brothels so he decided not to engage in alcohol-based social events. Instead, he spent much of his time alone and he knew that the other students considered him to be different. Despite his social exclusion, he became engaged to his future wife during his time at University.

Academically, Hindhede did very well. He was very popular among the professors and was the first medical student to graduate with the highest grade since 1847 even though he did not consider himself a genius. Instead, he attributed his success to his healthy diet and simple way of living.

During his studies he was taught that a high amount of meat protein was the most important component of a healthy diet. He accepted this knowledge and together with his housemate he started on a meat-rich diet. However, none of them felt comfortable physically on this diet and after returning to their original diet which consisted mainly of porridge and soup, they started feeling well again. Hindhede said following this episode ‘It was the reason for my first doubt on the wisdom of the “prophets”.’ ¹

‘The wisdom of the prophets’

Justus Von Liebig (1803–1873) (Figure 2) and Carl Von Voit (1831–1908) were leading figures in debates about nutrition throughout the nineteenth century. ³ According to Liebig, muscle tissue was degenerated when being active and therefore it had to be regenerated by the nutrition from the diet. Liebig claimed that only meat creates meat and therefore he recommended eating a high amount of meat and consuming his mass-produced meat extracts from South America. OPEN IN VIEWER

Liebig’s student, Von Voit, discovered that nitrogen, which was known as a degradation product of protein, was excreted completely through urine and faeces. This led to experiments with nitrogen balance in individuals on diets with different levels of protein and different levels of activity. Voit found the protein requirement did not increase during activity as Liebig thought but confirmed that a high daily protein intake is recommendable; a person weighing 70 kg with a moderate activity level should consume a daily diet of 118 g protein, 56 g fat and 165 g carbohydrate. ³ Hindhede, however, found the reasoning for these conclusion to be very doubtful, hence the term ‘prophets.’ ⁴

Medical career

After Hindhede’s graduation in 1888, his professors at Copenhagen University expected him to go into research. He was, however, more interested in clinical medicine and accepted a job as a family doctor near to his hometown. The rumour of the young doctor’s impressive achievement in medical school had spread to the area and his patients expected him to prescribe newer medication. However, since he believed a healthy lifestyle was more powerful than medication, he often had to disappoint patients by recommending lifestyle changes instead of prescriptions. In 1890, he became a hospital doctor in Herning and a year later the leading consultant at the hospital of Skanderborg. ²

Hindhede did not follow the contemporaneous views of treatments and he actively debated these matters in journals and newspapers. For instance, he decreased the use of medicine for various conditions, refused to perform appendectomies, stopped using alcohol as medicine and stated that good hygiene and high vegetable intake are important means of treating tuberculosis. Through these and other interventions the hospital decreased its mortality rate to only four percent. This compared favourably with a mortality rate of 13–16% at surrounding hospitals and Skanderborg spent just a quarter of that at neighbouring hospitals.

Even though he debated on many topics, healthy lifestyle was Hindhede’s main interest: ‘My main purpose since my 20th year of life has been to find the lifestyle that causes the most complete health, the greatest well-being. This very important question seems to have interested Doctors relatively little.’ ⁵

In 1895, Hindhede undertook his first nutrition experiment. For 1 month he only ate potatoes, strawberries, butter and milk. He found he had more energy than previously which made him certain that the Liebig–Voit theories on protein minimum were wrong. Consequently he and his family commenced a low-meat diet and he later used his children’s health and academic success as evidence for the efficiency of this diet. ⁵

Laboratory of nutrition

Hindhede also participated in the debate on the minimum protein for cattle and gained a lot of support from Danish farming associations. These associations and numerous doctors recommended that a government-funded laboratory of human nutrition with Hindhede in charge should be established. Despite resistance from professors at Copenhagen University, it was authorised by the Danish government in 1909. ¹

Hindhede ran nutritional experiments on two to three men at a time in the laboratory in contrast to most previous nutrition experiments which had been conducted on animals. The study participant was most frequently Frederik Madsen (1885–1947), a gardener who had been living on a vegetarian diet since 1906, and Hindhede felt blessed to have such a devoted assistant:

Professor Mann, London, once asked me if he could loan Madsen. But I had to say no. I could not do without Madsen. The monotonous diet is not even the worst, worse is the continuous control with urine and excrements. No long trip without a bottle of urine brought along. ⁶

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Figure 3.

Hinhede’s diet recommendation illustrated. People were recommended not to eat food from class B, to eat food from class C with moderation and to eat unrestricted of food from class A.

Hindhede wrote books about the benefits of a protein low diet and his message was popular among vegetarian enthusiasts. So although his ‘Economic Cooking Book,’ published during the First World War, does not sound very appetising today, it described very cheap food and may have been popular at the time. ⁹ Hindhede also travelled abroad in his search for the healthiest lifestyle and worked closely with other researchers across the world, including Professor Chittenden (1856–1943) of Yale University and the German dentist Carl Röse (1864–1947) who both conducted research on protein minimum and found results similar to Hindhede.^1,3,10 Carl Röse visited Hinhede in 1912 to study his work and after his return started his own experiments inspired by Hindhede. Max Rubner (1854–1932), a student of Voit, was one of Hindhede’s critics. He agreed that a diet with less than 118 g protein may be sufficient to maintain a neutral protein balance for some individuals. However, he also argued that individual variations may exist and that protein requirements depend on the source of protein. General guidelines on protein requirements should, Rubner stated, be set at a safe level in order to avoid negative nitrogen balance and consequently organ damage. ³ Thus, Hindhede met both support and opposition for his theories and he felt that some doctors in Denmark did not accept the new findings.

The World Wars

In 1917, when Denmark ran low on foods due to the trade blockade of the First World War, the government created a committee of four scientists that included Hindhede and four farmers to plan how to get Denmark through the food crisis with minimal starvation and mortality. ² The committee decided to reduce the national herds of pigs and cattle and instead use the harvest products to feed the Danish population in food ration packs. Consequently the production of pork was very low, only supplying the farmers, and beef was so expensive that only the rich could afford it. ¹¹ Thus, the diet of most of the population consisted of bread, barley porridge, potatoes, vegetables, milk and some butter which was in agreement with Hindhede’s theories on diet composition.

The food restrictions were introduced in March 1917. In an article published after the war, Hindhede compared the mortality rate of 25- to 65-year-old men in Copenhagen after the introduction of food restrictions with the mortality rate of the same group of people in the preceding 17 years. He found that the mortality rate from 1 October 1917 to 1 October 1918 was 34% lower than the average mortality rate over the previous 17 years. In other words, the death rate decreased from 12.5% to 10.4% corresponding to saving 6300 human lives if applicable to the whole Danish population of 3 million at the time.

Although, Hindhede did not assess whether the results were statistically significant, he confidently attributed the decrease in mortality to a reduction in excess consumption of meat and a low starvation rate. However, he also acknowledged that decreased alcohol production due to the crisis may have contributed to the low mortality. He believed no one would have starved during the war if Central Europe had adopted a similar strategy. ¹¹

In Germany, the high prevalence of hunger during the First World War led to immunosuppression, infections and a high mortality. As a result of these problems, there was an increased emphasis on dietary requirements and particularly protein requirements in the inter-war period. After gaining political power in Germany, the Nazi regime introduced a nutrition policy similar to the Danish with decreased meat production and consumption and increased consumption particularly of wholemeal bread. This policy was backed up by the Nazi-founded ‘Deutsche Gesellschaft für Ernährungsforschung’ (The German Association of Nutrition Research) which found inspiration in the experiments of Hindhede’s associate and admirer Röse. ³ Thus, it is possible that Hindhede influenced the German nutrition policy and in turn the health of the Germans during the Second World War (1939–1945).

Retirement and legacy

Hindhede led the laboratory until 1932 and then lived in retirement until his death on 17 December 1945. He had four children and one of his sons, Kristian Hindhede (1891–1969), became a structural engineer and director of several concrete manufacturing companies. ²

Hindhede succeeded in convincing many people that a healthy diet should contain less meat and more vegetables than that consumed previously and the importance of Hindhedes’s research was widely acknowledged among both researchers who supported and researchers who opposed his theories. ¹ Current dietary guidelines for Western countries are largely based on Hindhede’s. Thus, his theories were ahead of his time and he may have had an impact on the public health both nationally and internationally.^3,12 Hindhede’s work on minimum protein requirements may not be of the same importance in the developed world today where overconsumption is a bigger issue than hunger. However, the Swedish physician and nutrition debater, Stephan Rössner (born 1942), describes Hindhede as ‘a brilliant pioneer in understanding the role of protein in human nutrition.’ ⁹