The research, released as part of the Growing Up In New Zealand study, looked at how closely the Ministry of Health nutrition guidelines for infants are being followed.
Only 32.8% of infants met the vegetable intake recommendation of twice or more daily, 55.3% ate vegetables once a day, and 11.9% less than daily or never.
For fruit consumption only 48.2% ate fruit once a day and 14.7% ate fruit less than daily or never.
Just one in five infants were eating both fruit and vegetables at least twice a day and one in 16 infants did not eat fruit or vegetables daily.
On a more positive note, 80% of infants were meeting the guidelines for iron-rich food such as meat and other plant-based alternatives.
The study said 53% had tried food deemed inappropriate, such as sweets, chocolate, hot chips or potato chips and 39% had tried either coffee, cordials, juice, tea or soft drinks at nine months of age.
One of the research's authors, University of Auckland Associate Professor Clare Wall said this age was a critical window for growth and development.
"We know that not getting optimal nutrition in early life can have an effect on growth and development and can lead to unhealthy weight gain at a later age," she said.
She said foods high in sugar and salt are likely being given to infants because of food being eaten by the wider family.
"If those foods are available in the home and commonly eaten by other members of the family, then I suppose it's probably quite usual for infants to be consuming them as well," she said.
She said additional support may be needed for those families to make better choices for both their infants and children.
Above average for physical activity
Meanwhile, New Zealand children have low levels of physical activity compared with the amount of time they spend using technology.
But this country is above average internationally, in its support of physical activity, and children participating in organised sport.
The findings are part of the Physical Activity Report for Children and Youth, released this week.
The study was compiled by Melody Smith from the School of Nursing at the University of Auckland.
It finds children are involved in organised sport, active unstructured play and family exercise more than in other countries.
