Gross profit increased 53% from last year's first quarter.
Net income increased 228% to $43 million or diluted earnings per share of $0.90, compared with net income of $30 million or diluted earnings per share of $0.27 a year ago.
Net sales decreased $29.7 million or 3% to $1.88 billion, compared with the prior year period with favorable exchange rates benefiting net sales by $16 million.
Adjusted gross profit increased 39% to $107 million, and our adjusted gross profit margin increased to 10%, compared with 7% in the prior year period.
However, I would like to point out that if you apply the adjusted gross profit margin for the fresh and value-added produce segment of 8.7% to the $19 million of net sales impacted by COVID-19 in this segment, we estimate we would have delivered an additional $1.7 million in adjusted gross profit.
Adjusted operating income increased 140% to $58 million compared with the prior year period, mostly driven by increased gross profit.
And adjusted net income increased 154% to $42 million compared with the prior year period.
We achieved a diluted earnings per share of $0.90, compared to diluted earnings per share of $0.27 in the prior year period.
Excluding nonoperational and nonrecurring items, we delivered adjusted diluted earnings per share of $0.88, compared with adjusted diluted earnings per share of $0.34 in the prior year period.
Adjusted EBITDA increased 61%, and adjusted EBITDA margin increased 300 basis points when compared with the prior year period.
For the first quarter of 2021, net sales decreased $30 million or 5% compared with the prior year period.
For the quarter, adjusted gross profit in our fresh and value-added product segment increased 9% to $55 million, and adjusted gross profit margin increased 100 basis points.
We also pursued volume expansion during the quarter in the following product lines: pineapple volume increased 22% and avocado volume increased 12%.
Gross profit in our non-tropical product line decreased primarily in rates as a result of damage caused by severe rainstorms to some of our farms in Chile, which resulted in a $3.1 million inventory write-off.
Net sales in our banana segment decreased $9 million to $418 million while adjusted gross profit increased 93% or $23 million during the quarter, primarily driven by lower net sales in North America and the Middle East, mainly as a result of decreased sales volume, partially offset by strong demand in Asia.
Overall volume decreased 8%.
Pricing increased 7%, which offset an increase in production and procurement costs due to the impact of hurricanes Eta and Iota in Guatemala as well as inflationary pressure on cost of goods sold.
Selling, general, and administrative expenses decreased $4 million to $49 million, compared with $53 million in the prior year period.
The foreign currency impact at the gross profit level for the first quarter was favorable by $13 million, compared with an unfavorable effect of $6 million in the prior year period.
Interest expense net for the first quarter at $5 million was in line with the prior year period.
The provision for income taxes was $11 million during the quarter, compared with the income tax of $300,000 in the prior year period.
The increase in the provision was due to -- sorry, the increase in the provision for income tax of $10.7 million is primarily due to increased earnings in certain jurisdictions.
During the quarter, we generated $47 million in cash flow from operating activities, compared to $2 million in the prior year period.
As it relates to capital spending, we invested $34 million in the first quarter, compared with $17 million in the prior year period.
As of the end of the quarter, we received cash proceeds of $42.4 million in connection with our asset sales under the asset optimization program of which approximately $40 million was received in 2020.
We believe we're on track to achieve the $100 million program by the first quarter of 2022.
We paid down our long-term debt by $8 million, resulting in a total debt balance of $534 million.
And based on our trailing 12 months, our total debt to adjusted EBITDA ratio stands at 2.4 times.

Summary:
Net income increased 228% to $43 million or diluted earnings per share of $0.90, compared with net income of $30 million or diluted earnings per share of $0.27 a year ago.
We achieved a diluted earnings per share of $0.90, compared to diluted earnings per share of $0.27 in the prior year period.
Excluding nonoperational and nonrecurring items, we delivered adjusted diluted earnings per share of $0.88, compared with adjusted diluted earnings per share of $0.34 in the prior year period.