Health

How Lucy Wills discovered a medical marvel in Marmite

Some love it; some hate it; but there is something special about Marmite, as Lucy Wills discovered in the 1920s. The discovery that folic acid is important to the health of pregnant women is a classic story of serendipity in science.

Having recently finished a medical degree, Wills was recruited to Mumbai, India, to investigate why many pregnant women were suffering from a severe and often fatal form of anaemia. Wills began by studying the women’s living conditions and their stools, looking for any bacteria that might be causing their illness, but came up with nothing.

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She also paid careful attention to their diets, taking a record of everything they ate for five days. From this, she determined that deficiencies of vitamins A and C might be the cause of their anaemia and began experiments with rats to look for more evidence.

Fed on a diet of oatmeal and wholewheat flour, the death rate from anaemia among Wills’s rats ranged from 5 to 29 per cent. This was completely prevented by supplementation with whole milk. Further experiments with different diets appeared to back up her idea that deficiency of certain vitamins was causing anaemia in the rats. But these studies were compromised by an infestation of lice carrying bacteria that can produce anaemia in rats.

The breakthrough finally came when Wills carried out tests in monkeys, feeding them a diet based on that of women in Mumbai and giving supplements to some of the monkeys. One monkey on the baseline diet grew very poorly and its red blood cell count was very low. Then Wills replaced the yeast powder in its diet with Marmite, a commercial yeast extract made as a by-product of beer brewing. Marmite was included in soldiers’ rations during the first world war, and was believed to be a rich source of vitamins.

The monkey made a remarkable recovery. Seemingly by chance, Wills happened upon a potent source of whatever was missing from the diets of women suffering from anaemia during pregnancy.

Supplementing people’s diets with vitamins A and C had completely failed to treat anaemia in Wills’ clinical tests. But liver extract proved to work. Liver had earlier been found to be effective in another form of anaemia, named Addisonian anaemia, caused by defective gastric secretions. But much higher doses were needed in pregnant women, suggesting there might be another cause.

Wills learned from analysis by Harriette Chick at the Lister Institute that Marmite was rich in vitamin B. After its success at treating anaemia in monkeys, Wills tried giving it to 22 women, and it had a similar effect to that of liver extract. “Despite the small number, the results of the treatment were, however, so striking that I feel justified in reporting them – more especially as I am leaving India, and shall not be able to continue the work,” she wrote.

Vitamin B complex is actually a group of distinct compounds, only two of which had been identified at the time. After returning to the UK, Wills worked with biochemists P.W. Clutterbuck and Barbara Evans to identify the key factor in Marmite and liver extract. Folic acid was finally isolated from spinach in 1941, its name a derivation of folium, the Latin for leaf.

It was later discovered that folic acid not only prevents anaemia in pregnant women, but greatly reduces the risk of neural tube defects in the fetus that can result in spina bifida or anencephaly. In the US and Canada, fortified flour containing folic acid was introduced in 1998, which led to a dramatic fall in the rate of these birth defects. Following a long campaign by medical groups, the UK finally agreed to introduce folic acid fortification in 2018.

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