The team's website said a regular pre-race test showed the 25-year-old appeared to have low cortisol levels, which can be an indication of sub-optimal health.
Bennett has been hampered by a knee injury since placing 10th overall at Australia's Tour Down Under in January.
Under world cycling body UCI rules, Bennett is allowed to start the Giro but Team LottoNL-Jumbo is a member of the MPCC, an organisation which is committed to transparency in cycling and takes a strong anti-doping line.
MPCC rules state that riders with low cortisol levels should not race for eight days until the levels are within normal range.
Two other Kiwis are contesting the Giro d'Italia: veteran sprinter Greg Henderson for Belgian team Lotto-Soudal, and double Olympic bronze medallist Sam Bewley for Australian outfit Orica-GreenEDGE.
The first of 21 stages on the gruelling three-week tour is a team time trial from Sanremo in northern Italy.