Omega-3 Fatty Acids
Dietary fats are often viewed as the enemy in the United States, the result of a low-fat diet craze that swept the nation beginning in the 1960s (La Berge, 2008). Many people view fat as harmful to health, particularly cardiovascular function. However, certain types of dietary fats are actually good for you, for example, omega-3 fatty acids are healthy fats that are an essential part of any diet.
What Are Omega-3 Fatty Acids?
Omega-3 fatty acids are a type of polyunsaturated fat. The chemical conformation of these fats include a double bond, giving them a particular structure that determines their physiological role. Importantly, omega-3 fatty acids cannot be produced by the body (Harvard T.H. Chan School of Public Health, n.d.). Instead, they must be obtained from dietary sources.
Types of Omega-3 Fatty Acids
There are three major types of omega-3 fatty acids that are beneficial for human health: alpha-linoleic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). ALA is the most common form of omega-3 fatty acid in Western diets, and the body readily uses this nutrient for energy (Harvard T.H. Chan School of Public Health, n.d.).
Physiological Role of Omega-3 Fatty Acids
The most prominent positive role for omega-3 fatty acids is observed for cardiovascular health. A large body of scientific evidence suggests that increasing consumption of omega-3 fatty acids is associated with lower risk of heart attack, stroke, and other cardiovascular events (Office of Dietary Supplements, 2015). Omega-3 fatty acids appear to affect cardiac cells, helping them maintain efficient blood flow and a steady heart rate.
Omega-3 fatty acids are actively being studied for their role in other chronic diseases. For example, the anti-inflammatory properties of these nutrients may lower risk of multiple sclerosis, rheumatoid arthritis, Alzheimer’s disease, and other major medical conditions (Office of Dietary Supplements, 2015). More research is needed in these areas to clarify these associations.
Recommended Intake of Omega-3 Fatty Acids
In response to growing awareness about the importance for omega-3 fatty acids for health, the Food and Nutrition Board of the U.S. Institute of Medicine has developed guidelines for adequate daily intake of this class of nutrients. It is important to note that the adequate intake represents a goal for daily omega-3 fatty acid consumption; however, the exact needed amount of these healthy fats is still unknown. The recommendations are as follows (Office of Dietary Supplements, 2015):
Adult men should aim to get 1.6 grams of ALA each day.
Adult women should aim to get 1.1 grams of ALA per day.
Pregnant women have slightly higher omega-3 fatty acid needs, at 1.4 grams daily.
Breastfeeding women should aim to obtain 1.3 grams of ALA daily.
To date, there are no formal recommendations for daily intake of DHA or EPA.
Dietary Sources of Omega-3 Fatty Acids
Healthy individuals readily absorb omega-3 fatty acids from food sources. Foods that are good sources of ALA typically differ from those that provide DHA and EPA. Food sources of ALA include (Jump, 2014):
Walnuts: 2.6 grams per ounce
Chia seeds: 5.1 grams per ounce
Flaxseed oil: 7.3 grams per 1-tablespoon serving
Canola oil: 1.3 grams per tablespoon
Ground flaxseeds: 1.6 grams per tablespoon
Tofu: 0.2 grams per ½ cup serving
The best sources of ALA come from plant-based foods. In contrast, DHA and EPA are found in high concentrations in animal foods. Food sources of DHA and EPA include:
Pacific herring: 1.06 grams EPA and 0.75 grams DHA per 3-ounce serving
Pacific salmon: 0.86 grams EPA and 0.62 grams DHA per 3-ounce serving
Sardines: 0.45 grams EPA and 0.74 grams DHA per serving
Oysters: 0.75 grams EPA and 0.43 grams DHA per serving
Trout: 0.4 grams EPA and 0.44 grams DHA per serving
Canned tuna: 0.2 grams EPA and 0.54 grams DHA per serving
Vegetarians and vegans, who do not consume fatty fish, may have difficulty getting enough DHA and EPA in their diets. The body can convert ALA to DHA and EPA, but this requires relatively large intakes of ALA (Jump, 2014). Taking a DHA supplement is a possible way to boost intake of these beneficial nutrients.
It is also important to consider the ratio of omega-3 fatty acids to a related nutrient, omega-6 fatty acids. Getting too much omega-6 fatty acids (found in corn, sunflower, and vegetable oils) relative to omega-3 fatty acids may be detrimental to health (Harvard T.H. Chan School of Public Health, n.d.).