The 3 Most Important Types of Omega-3 Fatty Acids
By Freydis Hjalmarsdottir, MS
Omega-3 fatty acids are essential fats that have numerous health benefits.
However, not all omega-3s are created equal. Among 11 types, the 3 most important are ALA, EPA, and DHA.
ALA is mostly found in plants, while EPA and DHA are mostly found in animal foods like fatty fish.
This article takes a detailed look at the 3 most important types of omega-3s.
What Are Omega-3 Fatty Acids?
Omega-3s are a type of polyunsaturated fat. They're deemed essential fatty acids because they're necessary for health but cannot be made by your body.
Thus, you must get them from your diet.
Rather than being stored and used for energy, they play important roles in many bodily processes, including inflammation, heart health, and brain function.
Omega-3 fatty acids are a group of polyunsaturated fats that you must get from your diet. They have numerous health benefits.
1. ALA (Alpha-Linolenic Acid)
Alpha-linolenic acid (ALA) is the most common omega-3 fatty acid in your diet.
It's mostly found in plant foods and needs to be converted into EPA or DHA before it can be utilized by your body for something other than energy.
However, this conversion process is inefficient in humans. Only a small percentage of ALA is converted into EPA — and even less into DHA (3Trusted Source, 4Trusted Source, 5Trusted Source, 6Trusted Source).
When ALA is not converted to EPA or DHA, it is simply stored or used as energy like other fats.
Some observational studies link a diet rich in ALA to a reduced risk of death from heart disease, while others show an increased risk of prostate cancer (7Trusted Source).
This increase in prostate cancer risk was not associated with the other main omega-3 types, EPA and DHA, which seem to protect against this cancer (8Trusted Source).
Some seed oils, such as flaxseed and rapeseed (canola) oil, are also high in ALA.
ALA is mostly found in plant foods. Your body can convert it into EPA or DHA, though this process is highly inefficient.
2. EPA (Eicosapentaenoic Acid)
Your body uses eicosapentaenoic acid (EPA) to produce signaling molecules called eicosanoids, which play numerous physiological roles and reduce inflammation (9Trusted Source).
Chronic, low-level inflammation is known to drive several common diseases (10Trusted Source).
Various studies indicate that fish oil, which is high in EPA and DHA, may reduce symptoms of depression. Some evidence suggests that EPA is superior to DHA in this regard (11Trusted Source, 12Trusted Source).
One study in menopausal women noted that EPA reduced their number of hot flashes (13Trusted Source).
Both EPA and DHA are mostly found in seafood, including fatty fish and algae. For this reason, they are often called marine omega-3s.
EPA concentrations are highest in herring, salmon, eel, shrimp, and sturgeon. Grass-fed animal products, such as dairy and meats, also contain some EPA.
EPA is an omega-3 fatty acid that can reduce symptoms of depression and help fight inflammation in your body.
3. DHA (Docosahexaenoic Acid)
Docosahexaenoic acid (DHA) is an important structural component of your skin and the retinas in your eyes (14).
Fortifying baby formula with DHA leads to improved vision in infants (15Trusted Source).
DHA is vital for brain development and function in childhood, as well as brain function in adults.
Early-life DHA deficiency is associated with problems later on, such as learning disabilities, ADHD, and aggressive hostility (16Trusted Source).
A decrease in DHA in later life is also linked to impaired brain function and the onset of Alzheimer's disease (17Trusted Source).
As mentioned above, DHA is found in high amounts in seafood, including fatty fish and algae. Grass-fed animal products also contain some DHA.
DHA is very important for brain development and may protect against heart disease, cancer, and other health problems.
ALA, the most common omega-3 fat, is not biologically active until it's converted into EPA or DHA, which are essential for your body (3Trusted Source).
However, this conversion process is inefficient in humans. On average, only 1–10% of ALA is converted into EPA and 0.5–5% into DHA (4Trusted Source, 5Trusted Source, 6Trusted Source, 22Trusted Source).
Furthermore, the conversion rate depends on adequate levels of other nutrients, such as copper, calcium, magnesium, zinc, iron, and vitamins B6 and B7. The modern diet, especially vegetarianism, lacks some of these (23Trusted Source).
In addition, some omega-6 fatty acids compete for the same enzymes needed for this process. Therefore, the high amount of omega-6 in the modern diet may reduce the conversion of ALA to EPA and DHA (5Trusted Source, 24Trusted Source).
Other than being used for energy, ALA is not biologically active in your body. It needs to be turned into EPA and/or DHA to become active, but this conversion process is inefficient in humans.
8 Other Omega-3 Fatty Acids
ALA, EPA, and DHA are the most abundant omega-3 fatty acids in your diet.
However, at least eight other omega-3 fatty acids have been discovered:
- hexadecatrienoic acid (HTA)
- stearidonic acid (SDA)
- eicosatrienoic acid (ETE)
- eicosatetraenoic acid (ETA)
- heneicosapentaenoic acid (HPA)
- docosapentaenoic acid (DPA)
- tetracosapentaenoic acid
- tetracosahexaenoic acid
These fatty acids occur in some foods but are not considered essential. Yet, some of them do have biological effects.
At least eight other omega-3 fatty acids have been discovered. They're found in some foods and may have biological effects.
Which Omega-3 Fatty Acid is Best?
The most important omega-3s are EPA and DHA.
They're mainly found in seafood, including fatty fish and algae, meat and dairy from grass-fed animals, and omega-3-enriched or pastured eggs.
If you don't eat a lot of these foods, you may want to consider supplements.
EPA and DHA are generally considered the most important omega-3 fatty acids.
The Bottom Line
Omega-3 fatty acids are essential to maintain good health.
The most important types are EPA and DHA, which are abundant in fish oil, fatty fish, and many other seafoods. Algal oil is a good option for vegetarians and vegans.
Notably, EPA and DHA can also be formed from ALA, which exists in certain high-fat plant foods, such as flax seeds, flaxseed oil, walnuts, and chia seeds.
If you are eating inadequate amounts of omega-3-rich foods, supplements are generally recommended. You can easily buy them in stores or online.
Reposted with permission from our media associate Healthline.
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By Sara Lindberg
Whether you've hit a workout plateau or you're just ready to turn things up a notch, adding more strenuous exercise — also known as high-intensity exercise — to your overall fitness routine is one way to increase your calorie burn, improve your heart health, and boost your metabolism.
However, to do it safely and effectively, there are some guidelines you should follow. Keep reading to learn more about the benefits of vigorous exercise and how to safely dial up the intensity of your workouts.
What Is Considered Strenuous Exercise?<p>When it comes to exercise, the intensity of how hard you work out is just as important as the duration of your exercise session. In general, exercise intensity is divided into three categories:</p><ul><li>low</li><li>moderate</li><li>vigorous or strenuous</li></ul><p>For an activity to be vigorous, you need to work at 70 to 85 percent of your maximum heart rate, according to the<a href="https://www.heart.org/en/healthy-living/fitness/fitness-basics/target-heart-rates" target="_blank"> American Heart Association</a>. Examples of vigorous exercise include:</p><ul><li>running</li><li>cycling at 10 mph or faster</li><li>walking briskly uphill with a heavy backpack</li><li>jumping rope</li></ul><p>Low to moderate exercise is easier to sustain for longer periods since you work below 70 percent of your maximum heart rate and, sometimes, well below that level.</p><p>To reap health benefits, the <a href="https://www.hhs.gov/fitness/be-active/physical-activity-guidelines-for-americans/index.html" target="_blank">Physical Activity Guidelines for Americans</a> recommends that people age 18 and older get one of the following:</p><ul><li><strong>150 minutes</strong> of moderate-intensity aerobic activity per week</li><li><strong>75 minutes</strong> of vigorous aerobic activity per week</li><li><strong>combination of both types</strong> of activity spread throughout the week</li></ul>
Strenuous Exercise Vs. Moderate Exercise<p>Increasing your exercise intensity is fairly simple to do. You can still participate in your favorite activities — just at a more vigorous pace.</p><p>One of the benefits of more strenuous exercise is that you can reap the same rewards as moderate-intensity exercise but in less time. So, if time is of the essence, doing a more strenuous 20-minute workout can be just as beneficial as doing a slower 40-minute workout session.</p><p>Here are some examples of <a href="https://www.cdc.gov/nccdphp/dnpa/physical/pdf/pa_intensity_table_2_1.pdf" target="_blank">strenuous vs. moderate exercise<span></span></a>.</p><table><tbody><tr><th>Moderate intensity</th><th>Strenuous intensity</th></tr><tr><td>bicycling at less than 10 mph</td><td>bicycling at more than 10 mph</td></tr><tr><td>walking briskly</td><td>running, or hiking uphill at a steady pace</td></tr><tr><td>jog-walk intervals</td><td>water jogging/running</td></tr><tr><td>shooting baskets in basketball</td><td>playing a basketball game</td></tr><tr><td>playing doubles tennis</td><td>playing singles tennis</td></tr><tr><td>raking leaves or mowing the lawn</td><td>shoveling more than 10 lbs. per minute, digging ditches</td></tr><tr><td>walking stairs</td><td>running stairs</td></tr></tbody></table>
Benefits of Vigorous Exercise<p>Besides being more efficient, turning up the heat on your fitness sessions can benefit your health in a variety of ways. Let's take a closer look at some of the evidence-based benefits of a higher intensity workout.</p><ul><li><strong>Higher calorie burn.</strong> According to the <a href="https://www.acefitness.org/education-and-resources/professional/expert-articles/5008/7-things-to-know-about-excess-post-exercise-oxygen-consumption-epoc/?utm_source=Rakuten&utm_medium=10&ranMID=42334&ranEAID=TnL5HPStwNw&ranSiteID=TnL5HPStwNw-hYlKnAcfzfixAUsvnO6Ubw" target="_blank">American Council on Exercise</a>, working out at a higher intensity requires more oxygen, which burns more calories. It also contributes to excess post-exercise oxygen consumption (EPOC) or the "afterburn effect" that allows you to continue burning calories even after you finish working out. This means your metabolism will stay elevated for longer after a vigorous exercise session.</li><li><strong>More weight loss.</strong> A <a href="https://www.healthline.com/health-news/interval-workouts-will-help-you-lose-weight-more-quickly" target="_blank">higher calorie burn</a> and an elevated metabolism will help you lose weight more quickly than doing low- or moderate-intensity exercise.</li><li><strong>Improved heart health.</strong> According to a <a href="https://www.ncbi.nlm.nih.gov/pubmed/16377300" target="_blank">2012 study</a>, high- and moderate-intensity exercise appears to offer low chance of cardiovascular events, even in those with heart disease. Cardiovascular benefits may include improvements in:<ul><li><a href="https://www.healthline.com/health/diastole-vs-systole" target="_blank">diastolic blood pressure</a></li><li><a href="https://www.healthline.com/nutrition/15-ways-to-lower-blood-sugar#TOC_TITLE_HDR_1" target="_blank">blood sugar control</a></li><li>aerobic capacity</li></ul></li><li><strong>Improved mood.</strong> High-intensity exercise may also boost your mood. According to a large <a href="https://www.jstage.jst.go.jp/article/jpts/27/4/27_jpts-2014-736/_article" target="_blank">2015 study</a> that analyzed the data of more than 12,000 participants, researchers found a significant link between strenuous exercise and fewer depressive symptoms.</li><li><strong>Lower risk of mortality.</strong> According to a 2015 <a href="https://www.ncbi.nlm.nih.gov/pubmed/25844882" target="_blank">study</a>, researchers found that vigorous activity may be key to avoiding an early death. The study, which followed 204,542 people for more than 6 years, reported a 9 to 13 percent decrease in mortality for those who increased the intensity of their exercise sessions.</li></ul>
How to Measure Exercise Intensity<p>So, how do you know for sure that you're exercising at a strenuous level? Let's look at three ways to measure the intensity of your physical activity.</p><h3>1. Your heart rate</h3><p>Monitoring your heart rate is one of the most reliable methods for measuring exercise intensity. Exercising at 70 to 85 percent of your maximum heart rate qualifies as vigorous exercise intensity.</p><blockquote><strong><strong>WHAT IS YOUR MAXIMUM HEART RATE?</strong></strong>Your maximum heart rate is the fastest your heart can safely beat. To find out what your maximum heart rate is you need to subtract your age from 220. For example, for a 40-year-old person: <ul><li>220 bpm (beats per minute) minus age</li><li>220 – 40 = 180 bpm</li></ul>To work out at a vigorous pace, you'll want to exercise within 70 to 85 percent of your maximum heart rate. For example: <ul><li>180 x 0.70 (70 percent) = 126</li><li>180 x 0.85 (85 percent) = 153</li></ul>For a 40-year-old person, a vigorous training range is 126 to 153 bpm.<br></blockquote><p>You can check your heart rate while you're working out by wearing a heart rate monitor or <a href="https://www.healthline.com/health/how-to-check-heart-rate" target="_blank">taking your pulse</a>.</p>
How to Add Vigorous Activity to Your Workout<p>Adding strenuous activity to your weekly workout routine requires some careful planning. Fortunately, many of the activities that you do at a moderate level can easily be performed at a higher intensity.</p><p>One way of incorporating vigorous aerobic activity into your routine is to do a <a href="https://www.healthline.com/nutrition/benefits-of-hiit" target="_blank">high-intensity interval training (HIIT)</a> workout. This type of workout combines short bursts of intense activity — typically performed at 80 to 95 percent of your maximum heart rate — with recovery periods at 40 to 50 percent maximum heart rate.</p><p>To sustain this level of training, consider following a 2:1 work to rest ratio. For example, a <a href="https://www.healthline.com/health/treadmill-weight-loss#hiit" target="_blank">treadmill workout </a>or outdoor running session could include:</p><ul><li>running at 9 to 10 mph for 30 seconds</li><li>followed by walking at 3 to 4 mph for 60 seconds</li><li>alternating this work-to-rest ratio for 20 to 30 minutes</li></ul><p>Playing a fast-paced sport like soccer, basketball, or racquetball is another effective way to add strenuous activity to your fitness routine. Participating in <a href="https://www.healthline.com/health/benefits-of-a-spin-class" target="_blank">cycling classes</a> or swimming laps are other ways to build more strenuous exercise into your workouts.</p>
Safety Tips<p>Before you turn up the intensity on your workouts, it's important to keep the following safety tips in mind.</p><h3>Check with your doctor</h3><p>If you have a health condition or you haven't been active in a while, make sure you talk to your doctor before you start a high-intensity exercise routine. Your doctor can advise you on a safe level of exercise or how to become more active in the safest way possible.</p><h3>Build up the intensity slowly</h3><p>Going from low- or moderate-intensity workouts to vigorous exercise requires time and patience. While you may be ready to jump in with both feet, the safest way to add more vigorous exercise is to do it in bite-size increments. Pushing yourself too quickly can result in injuries and burnout.</p><p>For example:</p><ul><li><strong>Week 1:</strong> Swap out one moderate-paced cardio session for a HIIT workout.</li><li><strong>Week 2:</strong> Swap one moderate-paced session with a HIIT workout, and also add a circuit strength training session to your weekly routine.</li><li><strong>Week 3 and 4: </strong>Repeat weeks 1 and 2 before you start adding more high-intensity exercise to your weekly routine.</li></ul><p>It's also a good idea to space out your vigorous workouts throughout the week. Try not to do two strenuous sessions back-to-back.</p><h3>Don't forget the recovery time</h3><p>Your body requires more time to recover from a vigorous workout compared to a low- or moderate-intensity session.</p><p>To help your body recover, make sure to always include a cooldown and <a href="https://www.healthline.com/health/exercise-fitness/static-stretching" target="_blank">stretch routine</a> after strenuous physical activity.</p><h3>Stay hydrated</h3><p><a href="https://www.healthline.com/nutrition/7-health-benefits-of-water" target="_blank">Staying hydrated</a> is especially important when you're exercising hard. Not drinking enough fluids can affect the quality of your workout and make you feel tired, lethargic, or dizzy. It may even lead to <a href="https://www.healthline.com/health/dehydration-headache" target="_blank">headaches</a> and <a href="https://www.healthline.com/health/pain-relief/how-to-stop-leg-muscle-cramps" target="_blank">cramps</a>.</p>
The Bottom Line<p>Turning up the intensity of your workout sessions can be an effective way of boosting your overall health and fitness. It's also an easy way to save time when trying to fit a workout into your day.</p><p>To play it safe, always start slow and pay attention to how your body feels.</p><p>While vigorous exercise offers many health benefits, it's not appropriate for everyone. If you have a health condition or you haven't been active in a while, make sure to talk with your doctor before working out at a more strenuous level.</p>
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In January 2015, food sales at restaurants overtook those at grocery stores for the first time. Most thought this marked a permanent shift in the American meal.
Solving the Age-Old Problem of Spoiled Cheese<p>People have eaten pasta and cheese together for hundreds of years. Clifford Wright, the doyen of Mediterranean food history, says <a href="http://www.cliffordawright.com/caw/food/entries/display.php/topic_id/16/id/105/" target="_blank">the first written recipe</a> for macaroni and cheese was created in the court of the king of Naples in the 13th century, while <a href="https://food52.com/blog/9916-the-history-of-macaroni-and-cheese" target="_blank">the first reference</a> in an English language cookbook likely appeared in Elizabeth Raffald's 1769 book "The Experienced English Housekeeper."</p><p><span></span>An internet search for macaroni and cheese recipes will turn up over 5 million hits, but many still prefer to get theirs in a box – the kind with pasta that comes in shapes ranging from shells to Pokemon characters, accompanied by a packet of powdered cheese sauce.</p><p>Boxed macaroni and cheese was one outcome of the quest for ways to keep cheese longer. Some cheese gets better as it ages – a well-aged cheddar is one of life's delights – but once most cheeses hit their prime, <a href="https://www.dairyfoods.com/articles/91548-how-to-maximize-cheese-shelf-life" target="_blank">they tend to quickly go bad</a>. Before household refrigeration became common, many retailers wouldn't even stock cheese in the summer because it spoiled so quickly.</p><p>Processed cheese solved this age-old problem.</p>
When Natural Was Nasty<p>Today, food that's simple, pure and natural is <a href="https://theconversation.com/how-was-french-cuisine-toppled-as-the-king-of-fine-dining-66667" target="_blank">all the craze</a>, while <a href="https://apnews.com/c06a1200807c4b82a03452d08d480692" target="_blank">disdain for processed foods</a> is practically a credo among sophisticated consumers.</p><p>But when Kraft's different forms of processed cheese came out, they found widespread acceptance despite their strange textures. The fact that it wasn't natural didn't seem to bother consumers at all. In fact, as international food historian Rachel Laudan <a href="https://online.ucpress.edu/gastronomica/article/1/1/36/93394/A-Plea-for-Culinary-Modernism-Why-We-Should-Love" target="_blank">has noted</a>, back then, "natural was something quite nasty." She describes fresh milk as warm and "unmistakably a bodily secretion." Throughout the history of cookery, most recipes aimed to transform an unappetizing raw product into something delightful and delectable.</p><p>So for most consumers, processed foods were a godsend. They kept well, tended to be easily digestible and, most importantly, they tasted good. Many of them could be easily prepared, freeing women from spending entire days cooking and giving them more time to pursue professions and avocations.</p><p>In some ways, processed foods were also healthier. They could be fortified with vitamins and minerals, and, in an era before everyone had access to mechanical refrigeration, the fact that they kept well meant consumers were less likely to contract diseases from spoiled, rotten foods. Pasteurization of dairy products virtually <a href="https://www.the-scientist.com/foundations/rethinking-raw-milk--1918-65126" target="_blank">eliminated diseases like undulant fever</a>, while foods processed and canned in large factories were less likely to harbor food-borne illnesses that could crop up due to faulty or improperly sanitized equipment used by home canners.</p>
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Some fires won't die.
They survive underground during the winter and then reemerge the following spring, as documented in places like Alaska. They're called "overwintering," "holdover," or "zombie" fires, and they may have now awoken in the Arctic Circle — a fast-warming region that experienced unprecedented fires in 2019. The European Union's Copernicus Atmosphere Monitoring Service is now watching these fires, via satellite.