Fish oil is one of the most commonly used dietary supplements. It is rich in omega-3 fatty acids. It has been known to protect against heart diseases, lower blood pressure, and lower triglyceride levels.

According to a recent study published in the journal PLOS Genetics, the beneficial effect of fish oil on triglycerides is seen only in people with a certain type of genetic makeup.

What are Triglycerides?

Triglycerides (TG) are the most common type of fats present in your body. TG are commonly found in foods like butter, margarines, and oils. The extra calories that the body doesn’t need to use right away are also stored as triglycerides.

High triglyceride levels are considered to be a marker (indicator) for heart diseases. A blood sample reading of less than 150 milligrams per deciliter (mg/dL) is considered to be the normal level of TG. Higher levels of triglycerides may thicken the walls of the arteries, thereby increasing the risk of stroke and heart diseases.

Fish Oil

Fish oil is a rich source of omega-3 fatty acids, a type of polyunsaturated fatty acids (PUFA), which is very important for your heart health. Fish oil can be derived from consuming oily fish like mackerel and salmon or through supplements. Some fish oil products are approved by the US Food and Drug Administration (FDA) as prescription medications to lower triglycerides levels.

But, a recent study published in the journal PLOS Genetics claims that “taking fish oil only provides health benefits if you have the right genetic makeup.”

The Study

The study focussed on the effects of fish oil on triglyceride levels in the blood. The study also examined the levels of the other three blood lipids - high-density lipoprotein, low-density lipoprotein, and total cholesterol. All these types of fats (lipids) are biomarkers for heart diseases.

The study analyzed the data of 70,000 individuals taken from UK Biobank. The study cohort was divided into two - those who took fish oil supplements (around 11,000) and those who didn’t.

After running over 64 million tests, it was found that people on fish supplements who experienced a reduction in their triglyceride levels had a specific genotype of the GJB2 gene.

Individuals with the AG genotype who took fish oil decreased their triglycerides.

The study further revealed that individuals with the AA genotype who took fish oil had slightly elevated levels of triglycerides. The effects of fish oil on triglycerides in people with GG type could not be determined as present in the variant rs112803755. So, if you have your DNA raw data file with you, you can look up this rsID to find out your genotype!

Learn How To Use Xcode Life’s Gene Tool To Look Up Your Genotype here!

Recommendations to Reduce Your Triglyceride Levels

Apart from fish oil, there are also other effective methods to reduce your triglyceride levels. Some of them include:

Limiting your sugar intake

Excess sugar in your diet is turned into triglycerides, elevated levels of which are not good for your heart health. According to a study, replacing your sugary beverages with water can decrease your triglyceride levels by as much as 29 mg/dL.

Adopting a low-carb diet

The extra carbs in your diet are also converted into and stored as triglycerides. Following a low-carb diet has proven to be much more effective than following a low-fat diet in terms of reducing triglyceride levels.

Exercising regularly

HDL cholesterol is a type of good cholesterol. Increasing HDL levels can both help reduce triglyceride levels as well as counteract the effects of high triglycerides. Jogging for even two hours per week can reduce the levels of triglycerides.

Limiting Alcohol Intake

Alcohol is high in sugar and calories. If they are not used up by the body, they are converted into triglycerides. According to studies, even moderate alcohol consumption can increase your triglyceride levels by as much as 53%. This applies to people with normal triglyceride levels as well!


  1. High triglyceride levels are a marker for many heart diseases, as they contribute to plaque build-up in the arteries.
  2. Fish oil is one of the commonly used supplements and is rich in omega-3 fatty acids. It has been known to reduce triglyceride levels.
  3. According to a study, the effect of fish oil on triglyceride levels was found to be beneficial only in people with a specific genetic makeup.
  4. Upon analyzing the data of 70,000 people, the study found that fish oil reduces triglyceride levels only in people with the AG genotype of the GJB gene.
    Do You Carry The Beneficial AG Genotype? Find Out Using Xcode Life’s Gene Tool!
  5. Further, people with the AA genotype experienced a slight increase in triglyceride levels upon fish oil consumption.
  6. Some other effective ways of reducing triglyceride levels are regular exercising, lowering the consumption of high-sugar and high-carb foods, and limiting alcohol intake.

Use Xcode Life’s Gene Tool to find out your genetic marker for lowering triglyceride levels with fish oil supplements


  1. Should you take fish oil? Depends on your genotype
  2. GJB2 gene
  3. Substituting water for sugar-sweetened beverages reduces circulating triglycerides
  4. A low-carbohydrate as compared with a low-fat diet in severe obesity
  5. Effects of long-term, self-monitored exercise on the serum lipoprotein and apolipoprotein profile in middle-aged men
  6. Effect of moderate alcohol consumption on hypertriglyceridemia

Identical twins, also known as monozygotic twins, are believed to have identical sets of genes since they are formed from the same fertilized egg. 

Studies on identical twins have been used as a key research tool to tease apart the genetic and environmental contributions to a disease. For example, in the case of identical twins raised apart, if one has diabetes and the other doesn’t, blaming the environmental/lifestyle factors has been the classic approach - owing to their identical genetic material.

However, recent research suggests that this is not entirely true. Even twins developed from the same fertilized egg can have minor differences in their genomes - and these changes can happen during the first week of fetal development. 

The Study

According to a new study published in Nature, the genomes of identical twins can have small genetic differences which may impact their lives significantly. This study was performed by a group at deCODE genetics, an Icelandic biopharmaceutical company. 

The study involved 380 pairs of identical twins, two pairs of triplets, and their closely related families. Next-generation sequencing (NGS) technology was employed to sequence their genomes. NGS is the gold standard of sequencing in recent times that provides the test results within a day.

The results of this study show that, on average, 5.2 mutations differ between the pair of twins, and these differences occur in the early stages of growth.

Despite developing from the same fertilized cell, how do these mutations occur?

To understand that, let’s go over some terms:

Hereditary mutations occur in the gametes (organism’s reproductive cells - the sperm or egg cells). These are passed on from parents to their offspring.

When the sperm and eggs fuse to form the zygote (fertilized egg), these mutations are passed on to each cell of the resulting embryo. Since identical twins are formed from the same fused zygote, in theory, it only makes sense that they carry the same mutations.  

Somatic mutations occur only when the zygote starts to grow - during the first week of zygote development. They commonly occur as a result of errors in the cell division process.

In the case of identical twins, the zygote splits into two during the first week of development. 

While the hereditary mutations are split equally, the somatic mutations may be divided unequally in some cases. This random distribution of the somatic mutations can bring about certain differences between the twins. 

Coming back to the study, in 15% of the twin pairs studied, one twin had significantly more developmental mutations than the other. 

These differences, though very minor, can contribute to significant differences in health outcomes. In fact, they are enough to predispose one twin to developmental disorders like neonatal cancer and keep the other one healthy! 


  1. Scientists thus far have been conducting twin studies with the belief that they have identical genetic makeup, and thus, any differences in them can only be attributed to environment/lifestyle.
  2. A new study has come to light that challenges this theory. The study identified an average of 5.2 mutations difference between the pair of twins. 
  3. While hereditary mutations occurring in sperms and eggs are passed on equally between the twins, it’s not the case for somatic mutations. They develop during the first week of zygote development as a result of errors in cell division. These mutations are randomly distributed between the split zygote cells.
  4. The minor differences in the mutation distribution has the potential to have significant health impacts. In fact, they could increase the risk of conditions like neonatal cancer on one twin while keeping the other one healthy.


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