Omega-3 Fatty Acids - the Richest Sources from WHFoods
No
type of fat has been getting more recent publicity than omega-3s. However, much
of the omega-3 publicity you've heard has probably been focused on dietary
supplements rather than food. At the World's Healthiest Foods, I want to
provide you with a fresh look at omega-3s from the perspective of food and the
best ways to balance your meal plan for strong omega-3 support.
Getting
omega-3s from foods is a bit more complex than other nutrients as they come in
different forms, and some are simpler than others. The simplest is called
alpha-linolenic acid, or ALA. Like most vitamins, ALA is especially important
in our diet because our bodies cannot make it from scratch. Either we consume
it, or we don't have enough. Fortunately for us, many commonly eaten plant and
animal foods contain ALA.
For
other omega-3s, this all-or-nothing scenario is not the case. Under the right
circumstances, our bodies can usually take ALA and transform it into other
omega-3s. These other omega-3s are more complicated. The best studied are EPA
(eicosapentaenoic acid) and DHA (docosahexaenoic acid). In a large number of
research studies, there are clear health benefits provided by EPA and DHA that
are not provided by ALA. These health benefits involve support of many body
systems and decreased risk of many chronic diseases.
Omega-3
fatty acids are a group of polyunsaturated fats found in a wide variety of
foods, most famously in fish such as salmon. Of the non-animal sources two of
the World's Healthiest Foods, flaxseeds and walnuts, rate as excellent sources.
Sardines, salmon, Brussels sprouts, cauliflower and mustard seeds are rated as
"very good." 19 other foods are "good" sources. This should
give you plenty of choices to make sure your diet contains a variety of sources
of these important fats.
There
is no question that our bodies need the different forms of omega-3s — ALA, EPA
and DHA — to stay healthy, and we need to consume ALA-containing foods no
matter what because our bodies lack the ability to make ALA. But what about EPA
and DHA? Are we absolutely required to eat foods containing EPA and DHA?
World's Healthiest Foods rich in
omega-3 fats
FoodCalsDRI/DV
Basic Description
No type of fat has been getting more recent publicity than omega-3s, and you're very likely to have seen TV ads or heard radio infomercials about this unique type of fat. However, much of the omega-3 publicity you've heard has probably been focused on dietary supplements rather than food. In this profile, we'll provide you with a fresh look at omega-3s from the perspective of food and the best ways to balance your meal plan for strong omega-3 support.
Omega-3s belong to a broader group of fats called polyunsaturated fats. Sometimes you'll hear this group called "poly" fats. The specific members of this group are called polyunsaturated fatty acids, or PUFAs. What's most important about PUFAs—including omega-3s—is one special aspect of their chemical structure. They contain what are called "double bonds"—special connections that make them more flexible and interactive as fatty acids; they also make them more delicate and susceptible to damage. All PUFAs—including all omega-3s—contain at least two double bonds. But the position of the double bonds in omega-3s is unique and simply not found in other fats.
Some omega-3s are simpler than others. The simplest is called alpha-linolenic acid, or ALA. Like most vitamins, ALA is especially important in our diet because our bodies cannot make it from scratch. Either we consume it, or we don't have enough. Fortunately for us, many commonly eaten plant and animal foods contain ALA.
For other omega-3s, this all-or-nothing scenario is not the case. Under the right circumstances, our bodies can usually take ALA and transform it into other omega-3s. These other omega-3s are more complicated than ALA and contain more double bonds. The best studied are EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). EPA has five double bonds and DHA has six. In a large number of research studies, there are clear health benefits provided by EPA and DHA that are not provided by ALA. These health benefits involve support of many body systems and decreased risk of many chronic diseases.
So without question, our bodies need ALA, EPA, and DHA to stay healthy, and we need to consume ALA-containing foods no matter what because our bodies lack the ability to make ALA. But what about EPA and DHA? Are we absolutely required to eat foods containing EPA and DHA?
The answer to that question is particularly important since it can affect our entire approach to eating. If we only need to eat ALA-containing foods—and can trust our bodies to make all of the EPA and DHA that we need—we become free to choose whatever type of diet we would like, including a strict vegan diet that contains no animal foods whatsoever (including no milk, no cheese, and no eggs). That's because a wide variety of plant foods contain small-to-moderate amounts of ALA. However, if we need to obtain EPA and DHA directly from food, we become much more restricted in our food choices. For example, if we are trying to implement a strict vegan diet with no animal foods whatsoever and want to obtain DHA from our diet, our choices would most likely be limited to sea plants (which can contain DHA) or some fermented foods (like fermented soy foods) which had been allowed to ferment with the help of specific fungi that were capable of producing DHA. The absence of DHA in land plants is the reason for these very limited options.
Let's take some other examples. If we wanted to consume a generally vegetarian diet while still allowing ourselves to consume some fish, we would be able to get EPA and DHA from our food since fish can be a rich source of EPA and DHA. Similarly, if we wanted to consume a generally vegetarian diet while still allowing ourselves to consume some cheese, yogurt, milk, or eggs, we could also figure out how to obtain sufficient amounts of EPA and DHA from our food since these foods can contain both EPA and DHA. Or if we chose to eat meat while avoiding all fish, it would still be possible for us to get our EPA and DHA since meats can contain both EPA and DHA. (Their EPA and DHA content require that the cattle to have eaten a healthy amount plants that contain omega-3s.) The table below summarizes some of these basic relationships between omega-3s and diet types.
| Diet Type | ALA Food Sources | EPA and DHA Food Sources |
|---|
| Vegan | many plants | sea plants; possibly land plant foods when fermented with the help of certain fungi |
| Generally vegetarian but including fish | many plants and most fish | eggs, cheese, milk, and yogurt, especially when obtained from grass-fed animals but in varying amounts depending on additional factors; possibly land plant foods when fermented with the help of certain fungi |
| Generally vegetarian but including eggs, cheese, milk and yogurt (without fish, sea plants, or meat) | many plants; eggs, cheese, milk, and yogurt | most fish; sea plants; possibly land plant foods when fermented with the help of certain fungi |
| Plant-eating and meat-eating (but without fish or sea plants) | many plants; many meats | many meats, especially when obtained from grass-fed animals, but in varying amounts, depending on additional factors; possibly land plant foods when fermented with the help of certain fungi |
As you can see from the table above, our food choices can change quite dramatically if we are required to obtain EPA and DHA from our diet. But are we required to do so? Unfortunately, the answer to this question is not 100% clear from the research studies.
In principle, most healthy persons should be able to eat ALA-containing foods (like flaxseeds, walnuts, tofu, and spinach) and then rely on their bodies to convert ALA into EPA and DHA. Yet there is considerable scientific debate about our ability to get optimal amounts of EPA and DHA by relying exclusively on ALA-containing foods. That's because our body's ability to make EPA and DHA from ALA can become compromised under a variety of common circumstances.
For example, our body's ability to make EPA and DHA from ALA partly depends on the other types of fat that we eat. One of those other fat types is omega-6 fat. Omega-6 fats are more plentiful in foods than omega-3 fats. Because they are more plentiful, we often find ourselves consuming much more of them. Yet high consumption of omega-6 fats can directly reduce the amount of ALA that our body converts into EPA and DHA.
Or, to take another example: our body cannot do an effective job of converting ALA into EPA and DHA without a satisfactory supply of certain nutrients. These nutrients include vitamin B3, vitamin B6, vitamin C, and the minerals zinc and magnesium. If we are deficient in one or more of these nutrients, our bodies may not be able to provide us with optimal amounts of EPA and DHA, even when our ALA intake is sufficient.
Different people will want to use different dietary approaches to obtain their omega-3s. But based on a review of the research and on the chart information presented above, here are our basic recommendations:
- If you choose to avoid all animal foods (including seafoods), we recommend a discussion with your healthcare practitioner to determine possible supplementation with omega-3s.
- If you consume animal foods but avoid seafoods, we recommend extra care in selection of EPA- and DHA-containing animal foods. Animals that have consumed healthy amounts of omega-3s in their diet will be the most likely to contain EPA and DHA. As a general rule, these animals will have been raised in a natural setting throughout their lives and pasture-fed on a variety of grasses, legumes, and other plants.
- If your diet includes fish, 2-3 servings per week is a good target level for bringing fish-based EPA and DHA into your meal plan.
Omega-3 fatty acids are a group of polyunsaturated fats found in a wide variety of foods, most famously in fish. Because of recent research suggesting potential cardiovascular prevention and other health benefits, omega-3 fatty acids are currently a hot topic in nutrition research.
Of the World's Healthiest Foods, two (flaxseeds and walnuts) rate as excellent sources. We rate five of our listed foods as very good sources of omega-3, and 19 as good sources. This should give you plenty of choices to make sure your diet contains good sources of these important fats.
Role in Health Support
ALA, EPA, and DHA all play important roles in support of our health. Yet these roles are somewhat different.
Alpha-linolenic acid (ALA)
A large amount of ALA is sometimes used strictly for energy purposes. Our bodies can take ALA and use it to produce energy for our cells. In some situations, most of the ALA that we consume will get used in this way. ALA is also the primary building block for EPA and DHA. It's difficult to overstate the importance of ALA in this regard. Our immune, inflammatory, cardiovascular, and nervous systems simply cannot function correctly without sufficient amounts of EPA and DHA. When we don't have enough ALA, we don't have enough EPA and DHA (unless we've eaten foods that contain them). So ALA has a critical role to play in the health of many body systems as the key building block for EPA and DHA. There are basically two important metabolic roles for dietary ALA. The first is the breakdown of ALA to be used as an energy source. As much as 85% of dietary ALA is broken down to be used as an energy source.
The other major role for ALA is to be elongated to the related omega-3 fats EPA and DHA. The efficiency of this process will be discussed in more detail below.
Eicosapentaenoic acid (EPA)
Proper function of our inflammatory system depends on the presence of messaging molecules called prostaglandins. Many of these prostaglandins are made directly from EPA. Equally important, most of the prostaglandins made from EPA tend to be anti-inflammatory in their effect. Therefore, your risk of excessive inflammation and inflammation-related disease can be lowered through consumption of foods rich in EPA.
Docosahexaenoic acid (DHA)
Proper function of our nervous system—including our brain—depends on the presence of DHA. DHA is particularly important to brain function. Our brain is 60% fat by weight, and DHA makes up an average of 15 to 20% of all fat in our brain. If we tie these two facts together, we arrive at the following conclusion: DHA accounts for 9-12% of our brain's total weight! Drops in brain DHA levels are known to associate with cognitive impairment or slower neurological development in children. Nervous system deficiencies of DHA have been associated with a wide variety of problems, including neurodegenerative diseases like Parkinson's disease; cognitive problems including reasoning ability in children; and severity of multiple sclerosis.
A Special Note about Omega-3s and Cardiovascular Support
Prevention of cardiovascular diseases is one of the best-studied and substantiated role for omega-3s in the diet. Especially strong is the research supporting EPA and DHA in lowering heart disease risk. There is less research on ALA and heart disease, but research in this area still shows the ability of ALA intake to decrease risk. Unfortunately, the research we see in this area continues to focus more on dietary supplements than food, and in the future, we hope to see a much stronger emphasis on omega-3s from food.
The most crucial role for omega-3 fatty acids in health is arguably in prevention of cardiovascular diseases like heart attack and stroke. Much of the research in this area looks specifically at total EPA + DHA intake from diet and/or supplements.
Although there is comparatively less research on the topic, ALA intakes are associated with lower risk of cardiovascular disease independently of the other omega-3 fats. Still, the beneficial effects of diets high in ALA are likely to be more modest than diets rich in EPA and DHA.
SOURCE: http://whfoods.org/genpage.php?tname=nutrient&dbid=84#nutrientinteractions
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