These dates on packaged food items are even more important to us than they were prior to our CLL diagnosis, but for different reasons. In summary, we should eat foods before the 'Use-by' date to avoid the risk of food poisoning, especially if we are neutropenic. Foods may be eaten after the 'Best-before' date, but the food may not be as nutritious or as tasty if eaten after that date.
Tom Ross, Associate Professor in Food Microbiology, Food Safety Centre, School of Land and Food, University of Tasmania provides more detail here:
Photo: Barley freshly sprouting. With modern GPS units, farmers can now program the location of trees, fences,stock troughs etc in a paddock and have the tractor automatically sow, spray or harvest the crop. The units are so accurate, the following year's crop can be sown between the rows of the previous year's crop.