Squalene is a nutritional compound found in high amounts in olive oil and shark oil and is being researched for its ability to protect the body against cancer and the effects of aging.
Widely found in nature, it is also found in palm oil, wheat-germ oil, amaranth oil and rice bran oil (1).
Some studies show it may benefit cholesterol levels and may have cardioprotective effects. It also offers advantages for the skin as an emollient and antioxidant and for hydration.
Squalene may help prevent certain cancers. According to the authors of a paper published in a recent issue of World Journal of Microbiology and Biotechnology, squalene is an effective chemopreventive agent in reducing the incident of coronary heart disease and cancer (2).
Higher consumption of olive oil is considered the hallmark of the traditional Mediterranean diet, which has been associated with low incidence and prevalence of cancer, including colorectal cancer (3).
It has been theorized that the mechanism of action by which squalene exerts anti-cancer effects is through decreasing farnesyl pyrophosphate levels in cells, namely prenylation, which is required for oncogene activation.
Oncogenes are one of the two main types of genes that play a role in cancer. According to the American Cancer Society, when a proto-oncogene mutates (changes) or there are too many copies of it, it becomes a “bad” gene that can become permanently turned on or activated when it is not supposed to be. When this happens, the cell grows out of control, which can lead to cancer. This bad gene is called an oncogene (4).
Experimental studies have shown that squalene can effectively inhibit chemically-induced colon, lung and skin tumor formation in rodents.
Further studies are needed to fully identify its effects in human cancer protection, as well as possible harmful effects with long-term use (5).
Squalene may improve cholesterol levels. According to a 2014 mice study, squalene administration at a dose of 1 g/kg showed decreased reactive oxygen species in lipoproteins. Reactive oxygen species (ROS) are the contributors of oxidative stress which lead to various diseases and disorders such as cardiovascular disease, cancer, aging and various neurodegenerative diseases; supplementation also caused a specific increase in high density lipoprotein (HDL) cholesterol levels (6,7).
In a study of elderly patients with high cholesterol, combination therapy of prevastatin (a prescription drug that lowers the level of cholesterol and triglycerides in the blood) and squalene significantly reduced total cholesterol and LDL cholesterol (often referred to as bad cholesterol because high levels raise one’s risk for heart disease and stroke) and increased HDL cholesterol (known as good cholesterol because it absorbs harmful cholesterol and carries it back to the liver) to a greater extent than either drug alone (8).
In addition, the incidence of side effects was low.
In another study, however, supplementation with shark liver oil in 13 volunteers, with a content of 3.6g of squalene per day, had the opposite effect and increased the levels of total cholesterol and reduced the amount of good cholesterol (HDL) relative to total cholesterol (9).
Researchers stress that the effects of squalene on cholesterol levels may be different between humans, animals and isolated cells. It also may depend on the duration of treatment.
Squalene may offer other cardiovascular benefits. According to an issue of the Indian Journal of Medical Research, rats fed a squalene diet for four weeks had lower blood pressure and weight when compared to rats fed a non-squalene diet.
The levels of plasma leptin, glucose, cholesterol and triglycerides were also significantly lower in the squalene fed rats.
These effects of squalene are being further explored as a possible new approach for the management of high blood pressure and obesity (10).
Squalene may be beneficial to the skin. Squalene is an important skin surface lipid (SSL) film that protects the body from the external environment. Squalene can potentially protect the skin against oxidation and ultraviolet (UV) radiation.
Without enough squalene, UV rays can induce inflammation in the skin (11).
The presence of squalene in shark oil has been shown to be efficacious in treating some skin conditions. Its protective action from bacterial and fungal infections indicates that it may be helpful in patients suffering from atopic dermatitis (12).
Some studies show that it may also help fight UV-induced photoaging of the skin. In one study, 37 female volunteers over 50 years received two different doses [13.5 g/day (low-dose group) and 27 g/day (high-dose group)] of squalene for 90 days.
Facial wrinkles decreased significantly in the high-dose group, while collagen levels increased significantly in the low-dose group. Facial redness decreased, and pigmentation increased significantly in both groups. Both doses were effective at reducing cell death caused by UV radiation (13).
Squalene may be a potential treatment for Parkinson’s disease. Oxidative stress (an imbalance between the production of free radicals and the ability of the body to counteract their harmful effects through neutralization by antioxidants) plays a major role in the development of Parkinson’s.
Antioxidants have, therefore, attracted attention as a potential way to prevent this disease.
Squalene (known to have antioxidant properties) was recently researched in a Parkinson’s disease mouse model. Administration of squalene successfully prevented oxidative damage and prevented the toxicity of a chemical that destroys dopamine neurons (14). Parkinson’s disease belongs to a group of conditions called motor system disorders, which are the result of the loss of dopamine-producing brain cells (15).
Supplementation may cause stomach discomfort and loose stools. This was seen in the anti-aging study of 37 women taking 13.5 g/day or 27 g/day of squalene for 90 days (16).
While there are no reports of acute toxicity with squalene, there is no long-term evidence for squalene consumption above the doses commonly found in foods.
A typical beneficial dose (to mimic the dosages found in the Mediterranean diet) is estimated to be in the range of 300mg a day.
Since many of the studies on squalene have been done in cell or animal models, future human studies may help reveal the optimal dosage.
Squalene is a nutritional compound found in high amounts in olive oil and shark oil and is being researched for its ability to lower cholesterol and triglyceride levels, and to treat certain cancers and Parkinson’s disease. Early studies also show its potential in treating certain skin conditions such as atopic dermatitis and protecting the skin against oxidation and UV-induced photoaging of the skin.
Supplementation may cause stomach discomfort and loose stools. There are no studies available on side effects with long-term use.