Nuts (tree nuts and peanuts) are energy dense foods with complex matrices rich in unsaturated fatty acids and other bioactive compounds: high-quality vegetable protein, fibre, minerals, tocopherols, phytosterols, and phenolic compounds.
But did you know that the particle size and structure of masticated (chewed) nuts has a significant impact on nutrient release (bioaccessibility)?
In other words, the release of lipids (fats) depends on the effective breakdown of plant cell wall structure, which occurs through the chewing process. Therefore, the caloric values displayed on the nutrition labels can differ widely from the actual calories absorbed by our gastrointestinal tracts, resulting in approximately only 70-80% of calories being extracted. So, consuming 100g of walnuts (650 kcal) yields only about 455-520 kcal in energy values.
Also, walnuts produce a larger particle size post-chewing than almonds or pistachios, causing even less energy being extracted.
Naturally, the energy absorption increase as we alter the form of nuts through grinding, roasting (loss of cell wall integrity) or consumption of nut butters.
You may wonder what then happens with these partially digested particles, and the answer is, as you’d probably expect – they get pooped out.