These are the findings of the Pietermaritzburg Agency for Community Social Action, which has been monitoring food prices since 2006.

The Heart and Stroke Foundation of South Africa warned this week that escalating food costs affected diets and the health of consumers.

“Poverty and prosperity can predispose to diseases such as diabetes, high blood pressure, heart disease and strokes,” said the foundation’s Christelle Crickmore.

“In the long term a healthy diet and lifestyle hold substantial cost benefit in medical cost savings and increased productive working years.”

But the long-term benefits were a hard sell when people could not make ends meet in the short term, she said.

In January a food basket comprising starchy foods, sugar, beans, oil, milk, meat, fish and vegetables cost R1797. In March, according to Pacsa, it cost R1869.

Some foods tracked by Pacsa between November and March demonstrated a sharp increase: 10kg of potatoes rose from R35 to R60.32, four litres of cooking oil from R70.66 to R89.98 and 10kg of sugar from R103.65 to R117.98.

Pacsa researcher Julie Smith said the agency had found that households secured staple foods before more nutritional foods. There was less money to buy meat, dairy products and vegetables.

“This may have long-term and irreversible effects on health, productivity and well-being,” said Smith.

Food was an expense households prioritised because it was one they could control, she said. When food ran out two or three weeks into the month, families went into debt to cover the shortfall.

The South African Food Sovereignty Campaign is planning “sporadic, disruptive” protests against high food prices.

The campaign’s spokesman, Imraahn Mukaddam, said the cheap maize snacks that many people ate to get through the day contributed to obesity and diabetes.

Pick n Pay group executive David North suggested substitutes, such as rice for wheat-based products and chicken for beef, to cut costs.