From July 2018 article in Dunedin's "The Rock" - Dr. Alex Chisholm
Recently I was asked about the present enthusiasm in some circles and the popular press for "activating" nuts. Before you conjure up visions of nuts dashing off for a spot of exercise, "activating" in this context has quite a different meaning. The idea is that nuts need to be soaked or "activated" before being eaten to get the maximum benefits from the nutrients and to reduce any symptoms of gastrointestinal discomfort.
The basis for this idea is that nuts contain phytate, which can form complexes with minerals such as iron, zinc and calcium thus reducing their absorption. Cereal, grains and legumes also contain phytate and especially when they are a major staple in the diet they are often soaked to reduce the phytate and improve their nutritional value.
This is important in countries where cereals and legumes are a major source of minerals needed for growth and health. In NZ though, with our mixed diet, this is not an issue. So although nuts also contain some phytate the average consumption of nuts is low, the population intake of whole nuts being less than 3.5g/day. Even among those who are regular nut consumers it is likely that other foods will be contributing much more to the daily intake of iron, zinc and calcium. As most NZ'ers eat much less than the 30g/day recommended by the Heart Foundaton, the public health aim is to encourage increased nut intake. If people believed that nuts needed to be activated it is likely they would eat even less.
The methods of soaking and activating outlined in the popular media involve soaking for 12 hours, followed by drying for between 8 and 24 hours. These protocols also advocate the addition of salt to the soaking solution for the raw nuts. The use of really raw nuts is a concern due to possible contamination, especially of the nuts, once having been soaked, are not completely dried. As opposed to those completely raw nuts bought fresh from, for example, Uncle Joe's Walnuts and Hazelnuts that have been through temperature controlled drying after harvesting to keep them fresh and safe.
To assess the effects of soaked nuts on consumers acceptance and gastrointestinal tolerance the Nut Group at the University of Otago Nutrition Department carried out a study with 76 participants who consumed 30g/day of four different preparations of almonds for 12 days (whole unsoaked, whole soaked, sliced unsoaked and sliced soaked). The method used to soak the almonds was based on methods outlined in the popular media and involved soaking for 12 hours, followed by drying for between 8 and 24 hours. The results of the study showed the soaking does not improve gastrointestinal tolerance nor make the taste or texture of the nuts more acceptable. The majority of the participants did not experience any symptoms during the study and nuts in different forms are an acceptable food.
Contrary to claims in the lay literature soaking and subsequent drying increased the phytate concentration of whole almonds. It is possible to buy nuts which have been activated but these tend to be expensive.
REFERENCES: Taylor H.,Webster K., Gray A.R., Tey S.L., Chisholm A., Bailey K., Kumari S.,& Brown R.C.(2017) The effects of "activating" almonds on consumer acceptance and gastrointestinal tolerance. European Jounal of Nutrition, Advance online Publication DOI: 10.1007/s00394-017-1543-7
Gibson R.S., Raboy V., King J.C., Implications of Phytate in plant-based foods for iron and zinc bioavailibility, setting dietary requirements and formulationb programs and policies. NUTR REV 2018 jul 13. DOI: 10.1093/NUTRIT/NUY028.(Epub ahead of print)