Did you know DNA influences how you respond to omega-3?

All about the good omega-3 fats and your genes

Heart attacks kill over a half a million people each year in the US. Obesity is the most prevalent health crisis of our time. These two conditions have many different risk factors that endanger our health, and protective factors that promote a healthy body weight and good cardiovascular health. Omega-3 is one such substance that can help protect us. Yes, omega-3 is a fat, but it is a healthy fat with many benefits. However, it appears that some of us may be in a better position than others to reap the benefits from omega-3, all because of variation in one gene, NOS3.

Omega-3 belongs to a group of fats known as polyunsaturated fatty acids (PUFAs). It is found in high quantities in foods like fish, walnuts, poultry and eggs. There are three types of omega-3 fatty acids. One of them, ALA (alpha-linoleic acid), is essential which means it has to come strictly from our diet. The other two omega-3 fatty acids, DHA (docosahexaenic acid) and EPA (eicosapentaenoic acid), can be made from ALA. But the body can only make about 15% of what we require for these fatty acids, so EPA and DHA should also be included in your diet. Fish oils contain both EPA and DHA and plant oils are rich sources of ALA. For more information on omega-3 food sources and how much should be included in your diet, refer to the tables at the end of this article.

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Omega-3 fatty acids are required for growth and development and DHA is found in very high levels in the retina of the eye and the brain. They serve as the basis for hormones that control contraction and relaxation of the blood vessels, blood clotting and inflammation. Omega-3 fatty acids safeguard our health by lowering triglyceride (storage fat) levels to reduce our risk of heart problems, by boosting the effects of antidepressants to reduce risk of depression, and by counteracting memory loss associated with conditions like Alzheimer’s and dementia. Fish oils can also lower inflammation and as a result, offer relief from the symptoms of asthma and from the joint pain associated with rheumatoid arthritis.

All these benefits of omega-3 can be affected by the presence of a genetic variant of the NOS3 gene. Genetic variants are changes found in the DNA that can affect protein function. The NOS3 gene encodes an enzyme called nitric oxide synthase, which produces nitric oxide. Nitric oxide is a signalling molecule that signals the arteries to relax; helping to regulate blood pressure and increasing blood flow, providing protection against cardiovascular disease.

The link between omega-3 and NOS3 involves triglycerides, the storage fats in the bloodstream. Elevated triglyceride levels increase the risk of cardiovascular disease. People with one variant of NOS3, known as rs1799983 T, are at higher risk for increased triglyceride levels, but only if their diet is low in omega-3 fatty acids. So, if you have the NOS3 variant and don’t eat enough omega-3 fatty acids, you are more likely to have higher triglyceride levels than someone with the normal version of NOS3 who also has a low omega-3 consumption. Luckily, simply increasing your omega-3 intake should result in a reduction in your triglycerides.

Omega-3 deficiency can also cause fatigue, poor memory, heart problems, depression, poor circulation and a wide range of skin issues, including dryness, itchiness and discolorations. You might also experience problems with your eyesight, gain weight and be more prone to sickness. Deficiency during pregnancy puts a baby at risk of having vision and nerve problems. You can avoid all these issues by eating fish like salmon, tuna and mackerel at least twice a week. In case you don’t like the smell or taste of fish, you will want to consider either fish oil capsules, or seed oil capsules if you are a vegetarian. It is very important to not take more than the suggested dosage of these supplements, because overdose can cause vomiting, diarrhea, stomach pain, blood in the urine, nosebleeds and acute pancreatitis. High doses of omega-3 should only be taken under the supervision of a doctor. Remember to buy your supplements from a reputable source, because certain types of fish contain high mercury levels, which will make its way to the capsules.

If you live in North America, you are expected to live until you are at least 80, and omega-3 will certainly help you to get there. Those who carry the NOS3 variant will need to be more vigilant about their intake in order to enjoy the benefits of omega-3. If you just can’t fathom the thought of eating fish, there’s no need to worry, a simple genetic test can tell you your NOS3 genotype, but whether you can muster up enough courage to eat fish once you find out, is entirely up to you.

Adequate intakes for omega-3.

Adequate intakes (developed by the Food and Nutrition Board of the National Academy of Medicine) indicate an omega-3 level that is assumed to ensure nutritional adequacy. For infants, the adequate intake applies to total omega-3s, as human milk contains alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). For ages 1 and older, the adequate intakes apply only to ALA, because ALA is the only omega-3 that is essential.

Age Male Female Pregnancy Lactation
0–12 months 0.5 mg 0.5 mg
1–3 years 0.7 mg 0.7 mg
4–8 years 0.9 mg 0.9 mg
9–13 years 1.2 mg 1.0 mg
14+ years 1.6 mg 1.1 mg 1.4 mg 1.3 mg

Selected foods sources of omega-3.

The U.S. Food and Drug Administration (FDA) has established a Daily Value (DV) of 65 g for total fat but not for omega-3s. Thus, this table presents the amounts of omega-3 fatty acids in grams per serving only and not the percent of the DV.

Food g ALA per serving g DHA per serving g EPA per serving
Flaxseed oil, 1 tbsp 7.26
Chia seeds, 1 ounce 5.06
Flaxseed, whole, 1 tbsp 2.35
Salmon, Atlantic, farmed cooked, 3 ounces 1.24 0.59
Salmon, Atlantic, wild, cooked, 3 ounces 1.22 0.35
Herring, Atlantic, cooked, 3 ounces 0.94 0.77
Canola oil, 1 tbsp 1.28
Sardines, canned in tomato sauce, drained, 3 ounces 0.74 0.45
Mackerel, Atlantic, cooked, 3 ounces 0.59 0.43
Salmon, pink, canned, drained, 3 ounces 0.04 0.63 0.28
Soybean oil, 1 tbsp 0.92
Trout, rainbow, wild, cooked, 3 ounces 0.44 0.4
Black walnuts, 1 ounce 0.76
Mayonnaise, 1 tbsp 0.74
Oysters, eastern, wild, cooked, 3 ounces 0.14 0.23 0.3
Sea bass, cooked, 3 ounces 0.47 0.18
Edamame, frozen, prepared, ½ cup 0.28
Shrimp, cooked, 3 ounces 0.12 0.12
Refried beans, canned, vegetarian, ½ cup 0.21
Lobster, cooked, 3 ounces 0.04 0.07 0.1
Tuna, light, canned in water, drained, 3 ounces 0.17 0.02
Tilapia, cooked, 3 ounces 0.04 0.11
Scallops, cooked, 3 ounces 0.09 0.06
Cod, Pacific, cooked, 3 ounces 0.1 0.04
Tuna, yellowfin, cooked 3 ounces 0.09 0.01
Kidney beans, canned ½ cup 0.1
Baked beans, canned, vegetarian, ½ cup 0.07
Ground beef, 85% lean, cooked, 3 ounces 0.04
Bread, whole wheat, 1 slice 0.04
Egg, cooked, 1 egg 0.03
Chicken, breast, roasted, 3 ounces 0.02 0.01
Milk, low-fat (1%), 1 cup 0.01

Adequate intakes and food sources are obtained from the Omega-3 Fatty Acids Fact Sheet for Health Professionals (National Institutes of Health).

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