Sticking to a Mediterranean diet rich in fish, olive oil, legumes, fruit and vegetables is heart healthy, but expensive, maybe even prohibitively so, new research from Spain hints.

Consequently, "upstream" measures — such as taxes on unhealthy foods and/or subsidies on healthy foods — may be needed to "increase the probability of adopting a healthy dietary pattern leading to better health and disease prevention among the population," Dr. Maira Bes-Rastrollo told Reuters Health.

The researcher, from the Department of Preventive Medicine and Public Health, School of Medicine, University of Navarra, and colleagues studied the costs of Mediterranean and Western dietary patterns in more than 11,000 Spanish university graduates with a similar level of income. All of them were participating in a long term study launched in 1999 to assess ties between diet and obesity and long term health problems.

Their analysis revealed that the more closely these young adults adhered to the healthy Mediterranean diet, the more money they spent each day on food.

In contrast, the more closely they followed a "Western" diet - high in saturated fat, sugar, and red meat - the less money they shelled out each day on food.

This Spanish study, Bes-Rastrollo noted, shows that "a healthy Mediterranean dietary pattern is more expensive to follow than a Western dietary pattern and I am sure that the same study conducted in the United States would find the same results or even higher differences in costs between dietary patterns."

This "economic barrier" should be considered when counseling populations about following a healthy diet "because cost may be a prohibitive factor," she added.

The researchers also report that 31 percent of study subjects gained weight during the study - just over half a kilo, or 1.1 pounds, every year - and, after adjusting for factors likely to influence the results, people who spent the most on food were 20 percent more likely to gain weight, regardless of which dietary pattern they favored.

Those who had higher food bills tended to be older, were more likely to have quit smoking, tended to drink more calorie-laden fruit juice, soft drinks and alcohol and generally weighed more to begin with - suggesting that they were more prone to weight gain due to lifestyle or genetic factors, the researchers note.