Bristle Berries produce a Bristle seed after being eaten. Two Berries are produced per harvest, with Five harvests total. This makes ten potential new Bristleberry plants. Should the player have a cold room to keep the plants in, it easily becomes an infinite food source.
A suggestion I would give is to make it be a percentage chance to drop a seed upon eating a berry. 10% would be roughly fair, so one in ten of the full harvests would generate another seed. That's closer to a 1:1 ratio. Less than 10% would be more of a challenge and really push towards managing calories and food sources better.
Steps to Reproduce
Harvest and consume a Bristleberry plant.
Harvest and consume a Bristleberry plant.