The steadily increasing number of obese people in the world, over 600 million in the last count, attributed mainly to an imbalance between their calorie intake and energy expenditure, has come under scrutiny. New research suggests that to prevent and manage obesity in the world's population, omega-6 and omega-3 fatty acids need to be rebalanced in the food chain.
Nutrition policies have until recently concentrated on the mismatch between ‘calories in and energy out’ as the reason for growing obesity, under the mistaken belief that all calories are equal. New research clearly indicates that not all calories are the same and that an imbalance between intake of omega-6 and omega-3 could have a greater role in developing obesity.
The study revealed that humans evolved on a diet that had equal amounts of omega-6 and omega-3 fatty acids. This intrinsic balance is critical to babies' development during pregnancy and breast-feeding, and in preventing and managing chronic diseases.
Now, this 1:1 ratio has been replaced by an omega-6 to omega-3 ratio of 16:1. This substantial ratio difference has emerged as a consequence of significant changes in the food supply over the last 100 years.
Food technology and modern agriculture have led to production of vegetable oils, such as sunflower, safflower, cottonseed, soybean, and corn, which are rich in omega-6 fatty acids. These oils have increasingly found a place in kitchens around the world. Moreover, traditionally animals used to graze on grass containing omega-3, but the swap in animal feeds from grass to grain rich in omega-6, such as corn and soy, have also led to an increase of omega-6 fats in our diet.
The change in oils and animal feed has increased levels of linoleic acid and arachidonic acid - two types of omega-6 fatty acids. Linoleic acid levels have soared in the diet from oils and arachidonic acid from meat, eggs, and dairy.
The high levels of omega-6 can lead to increased white fatty tissue and chronic inflammation, which are both hallmarks of obesity and linked to type 2 diabetes, heart disease, metabolic syndrome, and cancer. Omega-6 can also prevent the browning of white fatty tissue to ‘good’ energy-burning brown fatty tissue and can increase the risk of blood clotting. Substituting meat for fish and changing cooking oils may rebalance the fats in our body.
Fatty acids act directly on the nervous system, influencing food intake and sensitivity of the hormones involved in blood sugar control and appetite suppression. While the body needs both omega-3 and omega-6, the balance between the two is crucial, say the researchers.
In addition to different populations metabolizing fatty acids differently, omega-3 and omega-6 are metabolically and functionally different. Previous studies have linked omega-3 fatty acids to a decrease in the development of fatty tissue and weight loss, while high concentrations of omega-6 have been associated with an increased risk of weight gain.
The researchers say, "The time has come to return the omega-3 fatty acids in the food supply and decrease the omega-6 fatty acids by changing the cooking oils and eating less meat and more fish. The composition of the food supply must also change to be consistent with the evolutionary aspects of diet and the genetics of the population."
"It is the responsibility of the governments and international organizations to establish nutrition policies based on science and not continue along the same path of focusing exclusively on calories and energy expenditure, which have failed miserably over the past 30 years," they conclude.