I believe you are RIGHT to question this. Flax seed (and the oil therein) is considered "healthy", and for good reason, but pretty much anything in "excess" can cause you problems. I quote "excess" because if your body has not experienced it before, then even low levels may be initially excessive.
If you have not taken Flax oil to any degree in the past, then I suggest you start off light - one teaspoon per day for a week, then two for two-weeks; then see how you feel. Your body will show you signs of stress if it doesn't "like" flax oil - if you listen very carefully, that is. For example, you may experience no side advers effects, so you can then experiment with increasing the dosage, but if you experience any of the following then you might want to cut back and try again:
loss of energy;
excessive weight loss/gain;
Stress will become manifest a dozen different ways for the same number of people, so it's hard to tell what may or may not happen. Indeed, you might not experience any unwanted side effects, too (which is what you're hoping for of course!).
Whenever you try something new, try to come in gently. The reason for this is that your body will become accustomed to dealing with this new entity, and will make some internal adjustments accordingly. Glugging down "a lot" of flax oil when it's new to you is more likely to cause an initial upset, and probably won't give you as many benefits as claimed.
One related point: flax seed oil oxidizes very easily, and the resultant product is extremely hazardous to health. For that reason, I always use [organic] flax seed, which I grind immediately prior to use. The seed husk protects the oil from oxidation. Two teaspons of oil in the form of ground seed is doable, especially if you drink lots of water to prevent consitiptaion (flax is VERY high in fibre - another great reason to take it). Two tablespoons of oil in the form of seeds might be too much though...
I congratulate you for having the wits to ask the question rather than just accept the writings of even someone as admittedly capable as Dr. John Berardi!
Good luck with the flax oil.