US natural and organic food retailer Whole Foods Market has reported a 51% increase in quarterly net income, due to stronger-than-expected sales and lower costs.

The company posted net income of US$38.7m, or 60 cents per share, for the first quarter to 18 January, compared to $25.6m, or 42 cents per share, in the year-ago period.

Whole Foods attributed the above-average increase in earnings to stronger-than-expected sales across the country, a positive contribution from its Harry’s stores and facilities compared to a loss in the prior year, and lower pre-opening expenses of $1.8m compared to $3.8m in the year-ago period.

Quarterly sales rose 21% to $1.1bn, while comparable store sales rose 14.7%. The company said it had benefited from extra custom in Southern California, where some of its rivals are grappling with ongoing strikes by grocery workers.

Whole Foods said that due to the higher-than-expected first quarter earnings and some expected continued positive benefit from the ongoing strike in the second quarter, the company is raising its guidance for fiscal year 2004 diluted earnings per share to between $1.93 and $2.02 from a previous estimate of $1.88 to $1.96.