South Africa was also ranked 13th in a division of 28 countries by income streaming. Chile topped that list, with Algeria in last place. It categorised South Africa as an "upper middle income" country.
The index, conducted by the Economist Intelligence Unit, found that countries in Sub-Saharan Africa and South Asia were the most vulnerable to high food prices.
"Of the 28 Sub-Saharan countries covered in the index, food consumption accounts for 50% or more of household spending in 20 of them," the unit found in its report, which was released earlier in July.
By comparison, in Switzerland, New Zealand and the US, 7% to 14% of spending was on food.
The index found high food prices could also be a problem in advanced countries, and that spending tended to be on processed foods and meats.
A separate study mentioned in the report this year found that one in seven elderly people in the US was food insecure – amounting to about 8.3-million people.
The recent economic downturn had placed greater strain on US households which were previously not at risk.
Low food prices could also cause food insecurity, especially in low income, agrarian economies.
Low prices depressed smallholder farmers' incomes, disrupted their ability to produce food, and were a disincentive to produce.
According to the index, economic activity in rural areas could be tied in some way to farming, and low incomes for farmers meant low incomes for all.
Sudden price changes and price shocks could force poor consumers and suppliers to sell important assets at low prices to maintain short term food security.
In the longer term, this kept families in poverty.
According to the statistics by the UN, cited in the index, global food production must rise by 50% by 2030 to meet demand.
According to Food and Agriculture Organisation (FAO) findings referred to in the index, the average adult needs 2 300 calories a day to lead a healthy and active life.
In the US, the national food supply was equivalent to 3 748 calories per person per day.
Sub-Saharan Africa was the only region where the average food supply was below the daily adult requirement, the FAO found.
The index also measures the volatility of agricultural production. Researchers said China experienced the least volatility during the last 20 years, with Algeria, Morocco and Tunisia among the greatest.
In China, volatility is lessened by its geographic size, and grain production is subsidised through a government minimum purchasing price that is higher than market rates.
Researchers noted that poor nutrition is a concern for wealthy and poor countries.
A malnourished child, for example, was more likely to drop out of school.
In the report's executive summary, the researchers comment that studies show a lack of food "is correlated with a substantial deterioration of democratic institutions in low-income countries, as well as a rise in communal violence, riots, human rights abuses and civil conflict". – Sapa