The problem of rancid nuts and seeds

"Nuts and seeds become rancid and lose their nutrients when they are hulled or shelled (so also when they are roasted (pistachio's, cacahuates, popcorn, ...), grinded (tahini and other nut and seed butters and pastes), or otherwise processed - bva). Deterioration begins immediately and continues, somewhat, even when vacuum-packed without oxygen. (...)

It is better not to eat nuts and seeds at all than to eat rancid ones."(1)

"Before chopping those nuts, carefully pick them over. A hollow-centered almond, Brazil nut, or other nut is rancid. Toos it. Rancid nuts are too toxic to feed to the dog. (...)
Because of their high oil content, nuts are prone to rancidity. The most healthful - and tasty - purchase is nuts in their protective shell. (...) Nuts in the shell keep for about a year if stored in a cool, dry place.
When purchasing shelled nuts, buy them whole and refrigerate or freeze them in airtight containers. Nuts exposed to light and sliced, broken, roasted, or blanched are rancid. Nuts completely contained in their protective skin like almonds and hazelnuts are better protected than other nuts." (4)

Possible negative effects of consumption of rancid nuts and seeds quoted by Pitchford are: irritation to the linings of the stomach and intestines; the oils in them cannot be digested or assimilated efficiently; poor immunity, cancer and other chronic diseases; destruction of vitamins A, E and F in the food plus those stored in the body; gall bladder and liver complaints.

"Since [tahini and other nut- and seed-butters] are often rancid, it is safest to make your own nut and seed preparations."(2)
"Because nut butters quickly become rancid, buy them in small quantities or make your own." (5)

"Homemade butters are easily made with your favorite seed or nut or a combination. Grind lightly roasted nuts in a blender, a meat grinder (use the finest attachment),a steel (not stone) grain mill, or a nut butter machine. A pinch of salt will increase shelf life and flavor. If the paste seems dry, stir in a little oil."(5)

"Sesame butter is made of whole roasted sesame seeds (...). It differs from the better known tahini, which is made of hulled raw sesame seeds, and [tahini] is therefore refined and denatured. Sesame butter [...] may replace tahini as a more wholesome ingredient. Sesame butter is high in vitamin E (a natural anti-oxidant, bva) and therefore has a longer shelf life than other nut butters. Once opened, sesame butter should be refrigerated, where it will hold for about 6 months. If it tastes or smells harsh, it is rancid and should be discarded."(6)

Sesame butter is recommended, if it is good quality and not rancid, but tahini not. "[T]ahini, a refined food to avoid, lacks fiber, many minerals and metabolic cofactors necessary for complete digestion."(7)

• "Buy nuts only in the shell. They will last up to one year.
• "Store hulled seeds in dark bottles in cold places. Heat and light speed oxidation. Do not store in plastic. Oil-rich food combines with plastic to form plasticides (which are toxic, bva).
• "Poisons and toxins tend to accumulate in all seeds, so it is important to buy organic non-sprayed ones. (...)
  

"The best way to eat seeds or nuts is to soak them overnight to initiate the sprouting process, which makes fats and proteins more digestible. Then dry and eat them raw or roast (15-20 minutes at 135°C in the oven for instance, bva) or cook them. They can also be cooked into cereals and broths, ground into meals or butters, or liquefied" (as in nut or seed milks and yogurts). (3)

Footnotes:
(1) Paul Pitchford, "Healing with Whole Foods: Asian Traditions and Modern Nutrition", North Atlantic Books; 3rd edition (2002), p. 530
(2) id. p. 146
(3) id. p. 530-531
(4) Rebecca Wood, "The new whole foods encyclopedia: a comprehensive resource for healthy eating", foreword by Paul pitchford, revised and updated ed., 1999, Penguin Books, p.231-232
(5) id. p.229
(6) id. p.310
(7) Paul Pitchford, "Healing with Whole Foods: Asian Traditions and Modern Nutrition", North Atlantic Books; 3rd edition (2002), p.533