There is no religious requirement to eat certain foods in Asatru. However, some Asatruars observe personal taboos. These personal taboos are based on personal gnosis or group gnosis, which are just as valid for determining an individual person's religious path as the teachings of the wider tradition of which they are a part. There are also traditional foods and beverages associated with holidays and sacrifices to specific gods in Asatru and other heathen sects, both in the Lore and in modern practice based on personal and group gnosis.
Some modern devotees of the goddess Sif avoid buying GMO wheat or GMO corn. This is a personal or group taboo observed as an act of devotion to the grain goddess. This practice is not about what the person eats, but about what the person supports with their purchasing power. Those who follow Sif can eat whatever random grain they are given or provided. When they have the opportunity to buy wheat products or corn products with their own money and make their own purchasing decisions, they will buy non-GMO wheat and corn if it is available. If certified non-GMO wheat and corn products are not available, it is also acceptable to purchase the waste products of a bakery, factory, or store, usually termed day-olds, markdowns, bakery leftovers, outlet goods, damaged, expiring, etc. The point is not about healthy eating, it is about refusing to support the damaging agricultural practices of GMO factory farming with one's money. Monsanto may be gone as a separate company, but everything it was still exists within the agricultural economic sector.
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The next principle is eating clean food produced without chemicals, preferably using 
