Dietary supplements are more popular today than ever before. They allow us to obtain nutrients and other compounds we generally don’t get enough through diet alone. Additionally, dietary supplements help us get access to healthy compounds we wouldn’t be able to consume otherwise. One of them is shark liver oil. While the idea of shark liver oil may seem odd at first, its benefits are numerous. Is weight loss one of them? Find out in this post.

What is shark liver oil?

Shark liver oil (SLO) is the oil obtained from the liver of several species of sharks including the dogfish shark (Squalus acanthias), the deep sea shark (Centrophorus squamosus), and the basking shark (Cetorhinus maximus). Interestingly, the liver accounts for 25% of the total body weight in these sharks (1).

Although it may seem shark oil is a modern-day medical discovery, it has been used for many years. In traditional Scandinavian medicine, shark liver oil was used for many purposes including immune system boost, management of immune-related diseases, as an anticancer agent, and more (2). 

Why did Scandinavians start using shark liver oil in the first place? 

It’s all down to the rarity of tumors in sharks and their ability to quickly resist infections. 

Today, shark liver oil is available as a dietary supplement in the form of liquid and capsules. It’s also found in some lip balms and skin creams. Consumption of SLO is associated with many health benefits thanks to the high content of (3):

  • Alkyglycerol (AKG)
  • Squalene
  • Omega-3 polyunsaturated (PUFA) acids

Shark liver oil is dark yellow to brown in color. It has a pungent taste and aroma, too.

Shark liver oil and weight loss

Although shark liver oil is studied extensively, the research primarily focuses on the anticancer and immune-boosting effects. Studies about shark liver oil and weight loss are scarce, practically nonexistent. But, many people still use shark oil to slim down and swear by it. 

While studies regarding the direct impact of shark liver oil on weight loss are lacking, current evidence is still promising. Compounds found in SLO could help you slim down. Below, we’re going to address substances from SLO that may help you lose weight.

AKG and weight loss 

Alkylglycerols (AKGs) are fatty substances found in blood-forming organs such as the liver, spleen, and blood marrow. What many people don’t know is that besides shark liver oil, AKGs are also present in red blood cells and breast milk.

These fatty compounds could support weight loss, besides offering a plethora of other health benefits. For example, a study from Evidence-Based Complementary and Alternative Medicine found the link between AKGs and weight loss. The main objective of this study was to investigate the effect of AKG on obesity and insulin resistance in mice fed a high-fat diet. Results showed some forms of AKGs have the potential to decrease body weight, triglyceride, cholesterol, glucose levels, insulin levels, and leptin levels (4).

Basically, AKGs (found in shark liver oil) can help you lose weight and they do so through several mechanisms. For example, these fatty substances can lower leptin levels. 

Leptin is a hormone released by fat cells in adipose tissues. The main function of leptin is to regulate and alter long-term energy expenditure and food intake. Since it is produced by fat cells, leptin concentration is directly associated with your body fat (5). Leptin levels tend to decline with weight loss, but may also signal the body to stimulate feeding and if you’re not careful it may cause weight gain (6). In other words, leptin levels have a lot to do with weight loss but you shouldn’t take them for granted. 

Many people make mistakes here thinking once they slim down their “job” is over. That’s when they regain the lost pounds. The more weight you put on, the higher leptin levels become. Therefore, by reducing leptin levels AKGs could exhibit a beneficial impact on your weight.

As seen above, AKGs can also decrease insulin and blood glucose levels. This is important because managing insulin and keeping it low is an important factor in successful weight loss (7). To make that happen it’s necessary to modify lifestyle and (8):

  • Exercise regularly
  • Avoid sugar
  • Decrease portion sizes
  • Reduce intake of refined carbs (or avoid entirely)
  • Add cinnamon to your foods and beverages
  • Try intermittent fasting
  • Increase intake of soluble fiber
  • Drink green tea
  • Eat fatty fish
  • Get enough protein

Omega-3 fatty acids and weight loss

Omega-3 fatty acids are the most well-known compounds in shark liver oil. These healthy fats are crucial for our health, but the body can’t produce them. We need to obtain Omega-3s through diet and supplementation. Compared to AKGs and squalene, Omega-3 fatty acids content in shark liver oil is relatively lower (9), but its effects are still significant. This is especially the case if you do not consume enough Omega-3 fatty acids through your diet and don’t take other supplements. 

Evidence shows supplementation with Omega-3 fatty acids can reduce body weight and body fat in overweight or obese individuals. It’s highly likely Omega-3s work through several mechanisms. For example, they may alter gene expression favoring increased fat oxidation in adipose, cardiac, liver, skeletal muscle, and intestinal tissues. As a result, Omega-3 fatty acids may decrease fat deposition in adipose tissue. 

Higher intake of these healthy fats has the potential to attenuate the sensation of hunger and may promote increases in lean muscle mass. The latter helps speed up metabolic rate and directly assists with the reduction of body fat. Moreover, supplementation with Omega-3s can have a vasodilator function i.e. it improves blood flow. Increased muscle blood flow during exercise may promote the disposal of nutrients and reduce their availability for lipogenesis i.e. fat storage (10). 

For men and women who want to maintain weight loss and prevent regaining lost pounds, Omega-3s can be helpful too. Studies reveal intake of Omega-3 fatty acids may attenuate further weight gain and could be useful in diet or as a supplement to maintain weight loss. The Omega-3s may work by modulating lipid (fat) metabolism, regulating adipokines such as adiponectin and leptin, alleviating inflammation of adipose tissue (11). 

For your reference, adiponectin is a protein hormone that participates in regulating glucose levels and the breakdown of fatty acids.

Benefits of Omega-3 fatty acids for healthy weight are best observed through the fact that persons with excess weight tend to have low levels of these healthy fats (12).

The increased satiety and feeling of fullness may help adhere to your healthy diet to achieve a stable and healthy weight loss (13). You see, many people struggle to slim down because they eat too many calories during the day. That happens due to overeating and frequent sensation of hunger, even if you’ve just had a meal. What Omega-3 fatty acids can do for you is that they suppress your appetite and help you feel full and satiated for longer. Appetite control has a direct impact on weight loss and its management. 

Does shark liver oil have side effects?

As seen above, shark liver oil may benefit weight loss or help people maintain weight in a healthy range. A lot more research is necessary, especially regarding the direct link between shark liver oil intake and weight loss. Further studies should also focus on the safety profile of SLO. 

At this point, there are no known side effects of shark liver oil due to the lack of information about it. Most studies on SLO focused on its anti-cancer properties. Also, they inspected short-term effects. 

Shark liver oil is not without controversy, though. Some studies have shown that high doses of SLO can increase cholesterol and may not be suitable for persons with atherosclerosis (14). While this applies primarily to high doses, people with atherosclerosis should be careful. Before you decide to use and buy shark liver oil, you may want to consult your doctor first. Your healthcare provider will tell you whether it’s safe for you to take or not.

Liver injury after supplementation with shark liver oil was also reported in one person (15). While doesn’t have to be an indicator that SLO causes liver problems (since the prevalence isn’t significant), you should be careful.

By careful we mean you need to consult your doctor first. Additionally, you should always keep in mind not all products are equal. Some are better than others. To be on the safe side, you should get shark liver oil from a trusted/reliable brand. 

In order to reduce the risk of side effects, you should stick to the recommended dosage. Avoid increasing or modifying dosage in any way on your own.

What is the dosage?

Information regarding the optimal dosage of shark liver oil is lacking due to a scarcity of studies. The supplementation period is also undefined. 

Daily dosage of SLO and length of supplementation may depend on several factors including preexisting conditions and individual needs. Everyone’s body is different meaning the metabolic rates may also vary. Plus, not everyone takes SLO to tackle the same health problem.

At this point, there is no known optimal dosage of SLO for weight loss. But for reference sake, 500mg of SLO a day may improve the immune system and support wound healing after the surgery (16). But, you should keep in mind doses higher than 15mg a day had adverse effects on blood cholesterol in studies (17).

Some brands recommend taking SLO supplements with food in order to improve absorption. At this point, there is no scientific evidence to confirm the accuracy of this claim. 

The best thing you can do is to adhere to dosage instructions displayed on the label. 

Does shark liver oil interact with medications?

At this point, there are no documented interactions between shark liver oil and medications. Safety profile-focused studies are necessary to learn more about this subject. However, higher Omega-3 fatty acids content in SLO is known for lowering blood pressure. For that reason, it could have an additive effect when combined with blood pressure-lowering medications (18, 19).

Before using shark liver oil, you should consult a healthcare provider regardless of the medications you’re taking.

What are other benefits of shark liver oil?

Dietary supplements allow us to prevent nutritional deficiencies and obtain compounds we usually don’t get through the diet. These products focus on natural ingredients and some of them have been used for centuries to treat various ailments. As mentioned above, shark liver oil was a major part of Scandinavian folk medicine. Indeed, SLO has some important health benefits and some of them are:

  • Anticancer properties – high AKG and squalene contents are believed to be behind anticancer effects of SLO. This is also backed up by low rates of tumors and cancers in sharks. AKG may have anti-tumor potential through activation of macrophages and exertion of anti-angiogenesis effects. Macrophages are a type of white blood cells that digest defective cells including cancerous cells. They are considered fundamental for antitumor defenses. The anti-angiogenesis effect means it restricts the development of new blood vessels that may feed cancerous cells thus slowing the growth and spread of the tumor. Squalene, in SLO, may protect against skin, colon, and lung cancers thanks to strong antioxidant properties (20)
  • Stronger immune system – fishermen have been using shark liver oil since ancient times to boost their immunity. These benefits are down to the AKGs which may stimulate antibody production and enhance the effectiveness of receptors and proteins that are necessary for a strong immune system. Squalene may also have immunostimulating properties, just like Omega-3 fatty acids. The latter can influence the body’s immune system defense through anti-inflammatory effects
  • Better heart health – squalene, a major compound in SLO, may have anti-atherosclerotic effects. That means this specific compound could prevent or counteract the accumulation of plaque in arteries. But, you should keep in mind the abovementioned potential of SLO to increase cholesterol in high doses. So you may want to be careful before you decide to buy it for your heart health. It’s also useful to mention that Omega-3 fatty acids are well-known for their potential to support cardiovascular health and functioning 
  • Improved fertility – AKGs in shark liver oil may improve mobility and speed of sperm
  • Skin health – squalene is the predominant component of sebum (skin oil) i.e. it hydrates the skin and may protect against UV damage
  • Reduced mouth ulcers – shark liver oil may decrease the appearance of recurrent mouth ulcers thanks to its immunostimulating effects 


Shark liver oil is available in liquid and capsule form. For many years fishermen have been using SLO and it had a significant place in Scandinavian traditional medicine. Shark liver oil has many benefits, but most studies focus on its anticancer and immunity-related properties. Supplementation with SLO may support weight loss primarily because AKGs and Omega-3 fatty acids can contribute to weight loss and its maintenance. A lot more research on this subject is necessary, especially regarding side effects and interactions.




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