I recently saw on p.$458$ of Montgomery-Vaugahn's ''Multiplicative number theory'' that the inequality
$$\int_{1}^{T} \zeta(1/2 + it) \mathrm{d}t = T + O(T^{1/2})$$
holds uniformly for $T\geq 2$, where $\zeta$ denotes the Riemann zeta function. From this result, it clearly follows that
$$\Bigg| \int_{1}^{T} \zeta(1/2+it) \mathrm{d}T \Bigg|\geq T^{1/2}$$
for all $T\geq T_0$. I need help on finding the $T_0$.