Prebiotics in the Ancient Diet 

Our ancestors were big-time eaters of inulin-containing plants, and prebiotic consumption was significantly higher than today, learned attendees at the 5th Orafti Research Conference in Boston.

Attendees at the Harvard Medical School Conference were told: "Future prebiotic research may be well-served with a better understanding of the nutritional landscape on which humans evolved." 

As our early ancestor moved from the rainforest to the parched savanna-woodlands of subtropical Africa, subsurface tubers, rhizomes, corms, and perennial bulbs, many rich in prebiotics, would have been a ready and important source of energy, they learned (Biosciences Microflora, 2005, Vol. 25, pp. 1-8).

The traditional view of our prehistoric (non-literate) hunter-gathering ancestors is of eating meat and cultivating vegetables and crops, like maize, but take a closer look at the facts and a different view is revealed.

Digestion-inhibiting compounds and plant toxins present in many below-ground food sources would have limited their role as staples in early diet of Homo until technological adaptations, such as fire, were introduced, says the journal Biosciences Microflora.

Interest in paleo prebiotics started with  study of the large earth ovens that our ancestors used to cook subsurface tubers over the course of several days. Such ovens have been found the world-over, with some dating back hundreds of thousands of years.

By cooking the prebiotic-rich plants in earth ovens, where temperatures were less than 100 degrees Celsius, the loss of prebiotic fiber from the cooking process was minimal, being less than 10 per cent. The archaeological record also shows that the pits used for these earth ovens got bigger and bigger, with some capable of producing between two and four thousand pounds (900-1800 kg) of edible prebiotic-rich foods.

Studies have shown that prebiotic-rich plants dominated the dietary intake of our ancestors in these regions, with about 60 per cent of the calorific intake coming from such sources. This would equate to a total dietary fibre intake of between 250 and 400 grams every day, with between 50 and 100 grams of prebiotic every day. Modern recommendations for oligofructose-inulin intake are between four and eight grams per day.

The next stages in this ongoing research could be to go back to the skeletal record to check for signs of disease, particularly osteoporosis. Significant research has reported that the prebiotic oligofructose-inulin increases calcium absorption, leading to higher bone mineral density, bone content, and lower risk of the disease.

Through studying paleo-diet, modern human nutritional studies, can consider our evolutionary-based and thus genetically determined optimal diet.