Fat quality

Most of the evidence is related to cardiovascular health. Data from decades of research via different methods (cohort studies, intervention studies) point in the same direction: replacing saturated and trans fatty acids in the diet with unsaturated fatty acids benefits blood lipids levels, and replacement by polyunsaturated fatty acids (PUFA: both omega-3 and omega-6) also reduces the risk of coronary heart disease.

Beyond cardiovascular health, emerging science suggests that fat quality could also impact health conditions such as metabolic syndrome, diabetes, and hypertension.

In addition, there is increasing scientific evidence that polyunsaturated fatty acids are needed for child growth and development. DHA, a long-chain omega-3 polyunsaturated fatty acid, is important for infant brain and visual development, with benefits that extend well into childhood.

“Current scientific evidence shows us that the most important thing about the fat you include in your eating plan is the quality of the fat. The best fats for health are oils such as – canola, soybean, corn, safflower and olive oils along with soft margarines made from these oils. You can further boost fat quality by choosing fatty fish more often than other meat sources, and adding walnuts, a source of omega-3, into your eating plan.”

Connie Diekman

Connie Diekman, M.Ed, RD, LD, FADA is Director of University Nutrition at Washington University in St. Louis, Missouri.

However, as always in science, debate continues in a number of areas:

There is concern about the safety of an unlimited increase in omega-6 fatty acids consumption. Contributions to the emerging LAskepticism are the well-documented reduction of the omega-3 long-chain PUFA status by dietary LA, its possible effects on early human development, its controversial pro-inflammatory potential, and its potential contribution to obesity. These questions warrant further investigation. However the WHO recommends a maximum of LAintake of 9% of total energy. LAintake in most countries ranges from 3 to 7% of total energy, suggesting that current consumption is unlikely to undermine the benefits of replacing dietary saturated fats with polyunsaturated fats to reduce the risk of cardiovascular disease.
Talking about the omega-6/omega-3 ratio is tempting by its apparent simplicity. However WHO/FAO and several other authorities have confirmed that this is not a useful concept. It is more important for health to ensure that recommendations are met for all types of essential PUFA: the omega-6 PUFA LA, the vegetable omega-3 PUFA ALA and importantly the mainly marine derived long-chain omega-3 PUFA (DHAand EPA).
Not all saturated fatty acids have the same effect on blood cholesterol – does this mean there should be recommendations for each individual type of saturated fatty acid? Many health authorities (including WHO/FAO) acknowledge this fact, but maintain their recommendation to limit the total amount of saturated for several reasons: there is still limited evidence that different saturated fatty acids would have different effects on clinical endpoints of cardiovascular diseases, and different types of saturated fatty acids generally exist together in the same foods and fats, and it is practically impossible to separate them in diet.
Whether trans fats of natural origin have the same deleterious effect on blood cholesterol and cardiovascular disease risk as trans fats from industrial origin is also still under debate. As a matter of fact, industrial trans fats have been studied more extensively, and there is a lot of emphasis in reducing the amounts of these trans fats in manufactured food products. Consuming low fat meat and dairy products can help limiting both saturated fat intake and trans fat intake from natural origin.

“The paradox about fat is that it makes foods taste yummy, but can contribute to heart disease and other health problems. The key is to choose the types and amounts of fat we eat wisely.”

Joyce Nettleton

DSc; Specialist in seafood nutrition and science communication

Why is fat quality so important for health?

“Choosing the right type of fat can often be confusing with the talk about saturated, unsaturated, trans, omega's, etc. So to make it simple focus more on plant based fats like nuts, seeds, oils and margarines made from oil Trans fatty acids continue to decrease in frequency of use but it is still important that you check food labels to make sure the type of fat used is not a partially hydrogenated fat.”

Connie Diekman

Connie Diekman, M.Ed, RD, LD, FADA is Director of University Nutrition at Washington University in St. Louis, Missouri.