‘Potatoes boost brain power, fight cancer, diabetes’

THE human brain is unique – no other animal possesses such a large brain relative to the size of its body.

It has been argued that an increase in meat consumption could have triggered the increase in size, but now scientists believe that we may have another food to thank: the humble potato.

Researchers suggest carbohydrate consumption, particularly in the form of starch, was critical for the extraordinary development of the brain over the past million years.

They say starches would have been readily available to ancestral human populations in the form of potatoes as well as in seeds, some fruits and nuts.

Commonly called sweet potato, Ipomoea batatas belongs to the plant family Convolvulaceae. In Nigeria, it is called edia-makara in Anaang, dankai in Berom, iyan-ebo in Edo, bia mbakara in Efik, ba-fadamee in Hausa, ediam-umani in Ibibio, ji-bekee or nduku in Ibo, beke buru in Ijo-Izon, dangali in Kanuri, dangura in Mambila, duku in Nupe, atsaka in Tiv, imitata or ole-oyinbo in Urhobo, anamo or odukun in Yoruba.

The new study combines archaeological, anthropological, genetic, physiological and anatomical data to argue that carbohydrate consumption was key in the human brain’s evolution.

Up until now there has been a heavy focus on the role of animal protein and cooking in the development of the human brain over the last two million years and the importance of starch rich plant foods has been largely overlooked.

Dr. Karen Hardy and her team at the Autonomous University of Barcelona say that there are five crucial reasons why a starch-rich diet was critical in human development.

The study was published in The Quarterly Review of Biology.

Firstly, the human brain uses up to 25 per cent of the body’s energy daily budget and up to 60 per cent of the body’s blood glucose.

While synthesis of glucose from other sources is possible it is not especially efficient, and such high glucose demands would not have been met on a low carbohydrate diet.

This need for carbohydrates would have been satisfied in part by the development of cooking.

While raw starches are often poorly digested in humans, when cooked they lose their crystalline structure and in turn make the assimilation of nutrients much easier.

The ability to use fire for cooking would have unlocked nutrients and enabled our ancestors to eat a far broader diet including tough, starchy roots.

Pregnancy and breastfeeding also place additional demands on the body’s glucose budget.

Low maternal blood glucose levels compromise the health of both the mother and her offspring, which suggest that a certain level of carbohydrates would have been essential for survival.

In addition to this, starchy carbohydrates would have been readily available to ancestral human populations in the form of tubers, as well as in seeds and some fruits and nuts.

Meanwhile, sweet potatoes may provide the next novel drugs for cancer and diabetes. Earlier study by Japanese researchers published in Journal of Agriculture, Food and Chemistry indicates that the growth of human cancer cells can be successfully suppressed with sweet potato extracts.

A previous study had demonstrated that the phytochemicals in sweet potato have significant antioxidant and anticancer activities. The antioxidant activity was directly related to the total amount of phenolics and flavonoids in the extracts. Researchers suggest that the additive roles of phytochemicals may contribute to its ability in inhibiting tumor cell proliferation in vitro.

Also, researchers from Austria, Italy and Switzerland had demonstrated the tolerability, efficacy, and mode of action an extract of white sweet potatoes on metabolic control in type 2 diabetic patients.

The researchers suggest that despite its “sweet” name, sweet potato may stabilize blood sugars and lower insulin resistance. Other studies have shown that the flavone extracted from sweet potato leaf could control blood sugar and modulate the metabolism of glucose and blood lipid, and decrease outputs of lipid peroxidation and scavenge the free radicals in non-insulin dependent diabetic rats.

India researchers have demonstrated the cyhoneypotxic and antioxidant activities of sweet potato. The study published in the International Journal of Pharmacy and Pharmaceutical Sciences concluded: “On the basis of the above results it can be concluded that he ethanolic extract possess significant anticancer and antioxidant activities studied by in vitro models. The presence of flavonoids and related phyto-constituents may be responsible for the activity. Further investigations are required to find active component of the extract and to confirm the mechanism of action. Further studies warranted, for isolation of the constituents responsible for the activity and also to explore the exact mechanism of action of the activity.”
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The researchers also point out that humans possess six salivary amylase genes, while other primates just have two, increasing the ability to digest starch.

The exact date at which these additional genes appeared remains uncertain, but analysis suggests it was at some point in the last million years.

Hardy explained that after cooking became widespread and the salivary amylase genes multiplied, this increased the availability of dietary glucose to the brain and foetus which, in turn, allowed the acceleration in brain size which occurred from around 800,000 years ago onwards.