It seems like every day there is a new health benefit that omega-3 fatty acids bestow upon you: they’re good for your heart, improve arthritis, reduce depression, help with hot flashes during menopause, and now they help boost your metabolism.

But what are omega-3 fatty acids, where can you find them, and why are they all the rage?

Just as amino acids of protein are essential — meaning you need to get them from your diet — so are omega-3 fatty acids. Your body cannot make these fats, but they’re required for many functions such as building cell membranes and controlling blood clotting and inflammation in the body.

Most Americans don’t get enough omega-3 fatty acids. There are three kinds found in foods:

  • Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are mostly found in fatty fish like salmon and tuna. These’re easiest for your body to use.

  • Alpha-linolenic acid (ALA) is found in nuts such as walnuts, seeds and seed products such as flaxseed and flax oil, vegetable oils such as soybean and canola oil, green leafy vegetables such as Brussels sprouts and kale, and in some grass-fed animal products. It’s also often used to fortify products like eggs, peanut butter, and granola bars. It’s more difficult for your body to use this type of omega-3.

Aim to get at least one rich source of omega-3 into your diet every day:

  • Eat two servings of fatty fish per week, such as tuna, wild salmon, and sardines.

  • Add ground flaxseed (flaxmeal) or walnuts to oatmeal, salads, and yogurts.

  • * Choose olive, canola, and soybean oil for salad dressings instead of creamy ranch or Caesar.

  • Scramble up omega-3 fortified eggs in the morning (or for dinner!)

If you aren’t able to get omega-3s into your diet, you might consider taking a supplement.

Check with your doctor before taking omega-3 supplements such as fish oil, which functions as a blood thinner. In high doses, or when taken with other meds, it could have a negative effect on your health.

Saturated and trans fat in your diet can negate the positive effects of omega-3, so make sure you keep those to a minimum. Instead, opt for omega-3s and other sources of unsaturated fats, like avocado, nuts, nut butter, and seeds.

So how do omega-3s affect metabolism? Getting enough fat is important for satiety — you feel fuller longer when you get a serving of fat in your meal. There’s evidence that omega-3s have an even better effect than other fats due to stimulation of leptin, the hormone that tells your brain you are full.

When there’s not enough leptin circulating in your body, there’s a higher level of the neurotransmitter neuropeptide Y, which signals the hunger reflex. An increase in neuropeptide Y can decrease thyroid function and your metabolic rate.

What else can omega-3s do for you?

  • Reduce symptoms of arthritis like stiffness and joint pain.

  • Lower risk for depression; fish oil may boost the effects of antidepressants.

  • Improve visual and neurological development of infants in utero.

  • May lower triglycerides and reduce risk for heart disease (although emerging research contradicts this)

  • Preliminary research shows it could reduce your risk for Alzheimer’s disease and dementia.

Although getting more fatty fish is a great idea to boost your health, you want to choose wisely. Some fish have higher levels of environmental toxins like mercury, which comes from industrial pollution. Fish absorbs the mercury that’s released into the water, and it builds up inside them.

Bigger fish and those that are farm raised have higher toxin levels. Women of child-bearing age, pregnant women, and children should heed the following guidelines:

  • Avoid fish that are high in mercury: shark, swordfish, tilefish, king mackerel. Limit farmed fish.

  • Choose these lower-in-mercury options: canned light tuna, wild salmon, shrimp, Pollock, and catfish — up to 12 ounces per week.

  • If consuming fish caught by friends or family in local waters, but you're unable to find information about the mercury content, stick to less than 6 ounces and don’t consume any other fish that week.

You can also refer to the Environmental Protection Agency’s website for more information about the fish around where you live.