As a clotting factor, fibrinogen is essential for the body’s healing processes. However, high levels can be harmful to your health. Read on to understand the hidden causes and risks of high levels and how to lower fibrinogen naturally.

Hidden Causes of High Fibrinogen Levels

1) Stress

Multiple studies (158 participants; 636 participants) have found that fibrinogen levels increase immediately after a stressful task [1, 2].

In addition, a study with 302 people determined that people with high cortisol levels also had elevated fibrinogen [3].

This relationship is possibly due to the increased production of the fibrinogen genes (FGA, FGB, and FGG) by IL-6 [4].

Stress can quickly increase your fibrinogen levels.

2) Pregnancy

Pregnant women experience elevated levels of fibrinogen, probably to prevent excessive bleeding when giving birth [5, 6].

As pregnancy progresses, fibrinogen concentration increases up to three times its normal range and then returns to baseline 4 to 6 weeks after delivery [7, 8].

Fibrinogen levels normally rise throughout pregnancy to prevent excessive bleeding during childbirth.

3) Smoking

Multiple studies (9,127 participants; 200 participants; 11,059 participants) have found that smokers and ex-smokers have significantly higher fibrinogen levels than non-smokers (up to 53% more fibrinogen, and up to 11% more, respectively) [9, 10, 11].

Smoking more seems to further increase fibrinogen, and fibrinogen levels do not return to normal until a person has refrained from smoking for 15 years (11,059 participants; 118 participants) [11, 12].

Smokers who had diabetes and/or high cholesterol had especially high fibrinogen (200 participants; 118 participants) [10, 12].

Smoking increases fibrinogen levels, which take years to return to normal even after people quit.

4) Birth Control

Oral contraceptives increase fibrinogen levels, especially those with high estrogen concentration (randomized crossover study with 28 participants for 16 weeks; survey of 200 women) [13, 14, 15, 16].

Estrogen may elevate fibrinogen by increasing the expression of the FGG gene and production of the protein, as seen in rats [17].

As shown in a study with 194 participants, this effect was compounded in women who smoked while on birth control [18].

Birth control pills increase fibrinogen levels, especially in women who smoke.

5) Genetic Mutations

Multiple studies (895 participants; 1,002 participants; 7,329 participants) estimated that genes account for 34 to 46% of the variation in fibrinogen levels. A number of mutations associated with high fibrinogen levels are discussed below [19, 20, 21].

The inherited disorder homocystinuria increased blood levels of the amino acid homocysteine (3,216 participants), which lab experiments suggest may inhibit the breakdown of fibrinogen, leading to elevated levels [22, 23, 24].

Genes account for almost 50% of the variation in fibrinogen levels; variants that increase homocysteine raise fibrinogen.

6) Age

Multiple studies (9,127 participants; 72 participants; 12 participants; 3,967 participants) have found that older people tend to have higher levels of blood fibrinogen, with concentrations increasing around 0.1 – 0.2 g/L each decade [9, 25, R, 26].

7) Cold Temperatures

Cold temperatures increase fibrinogen levels, resulting in chronic elevation during the winter months (2-hour study with 12 participants; yearlong study of 1,002 participants; yearlong study of 24 participants) [27, 28, 29, 30].

Old age and cold temperatures can increase fibrinogen.

8) Diet

Elevated fibrinogen of 206 Japanese emigrants in Hawaii was associated with more iron and sugar consumption. This could implicate the prevalence of meat and high glycemic foods in the Western diet, which is also associated with cardiovascular disease [31].

A survey of 1,854 people found that high fibrinogen was associated with low blood concentrations of minerals and vitamins, such as iron and vitamin B6, as well as high levels of cholesterol and fatty acids. This suggests that both under- and overnutrition can increase fibrinogen [32].

A study of 16 individuals also found that fibrinogen increased by 20 to 40% directly after the participants drank a protein shake or balanced-meal shake, but not after drinking water [33].

Meat-heavy, high-carb diets increase fibrinogen; diets low in iron and vitamin B6 have a similar effect.

9) Obesity

Multiple studies of over 1,500 people revealed that people who are overweight generally have high fibrinogen [34, 10, 35, 31].

Though a causal relationship has not been proved, the ability of exercise to decrease fibrinogen suggests body fat may determine fibrinogen levels (87 participants; 3,967 participants) [34, 26].

Being overweight or having more body fat may increase your fibrinogen levels.

Health Risks of Elevated Fibrinogen

1) Promotes Inflammation

Fibrinogen activates molecules that increase inflammation (IL-8, MCP-1, MMP-9, Mac-1) while inhibiting molecules that would decrease it (PPARα, PPARγ), both in the blood and the brain [36, 37, 38, 39].

Mice with either low fibrinogen levels or mutated fibrinogen that cannot bind to white blood cells have significantly decreased inflammatory responses [40, 41].

Certain types of bacteria (Streptococcus) bind to fibrinogen in order to promote inflammation during infection [42].

Therefore, therapies to decrease fibrinogen/white blood cell binding may improve symptoms of common inflammatory diseases like rheumatoid arthritis, multiple sclerosis, and bacterial infection [40, 43, 44, 45].

High fibrinogen levels increase inflammation in the whole body, while low levels have the opposite effect.

2) Increases the Risk of Harmful Blood Clots

High fibrinogen is associated with higher rates of heart disease, blood vessel dysfunction, and stroke. By some estimates, high fibrinogen predicts these diseases as well as high blood pressure and smoking [46, 47, 48, 49].

In a study of 1,363 patients, high fibrinogen levels were also associated with a greater risk of developing heart disease within 18 months [50].

Furthermore, a longitudinal study of 158 participants concluded that people with larger fibrinogen spikes due to stress had poor blood vessel health, and therefore a greater risk of heart disease 3 years down the road [1].

Elevated fibrinogen is linked to high cholesterol, particularly the bad (LDL) kind, in people without any history of cardiovascular disease [12, 51].

Fibrinogen and its degradation by-products were also found in the plaque and cholesterol that builds up on the walls of blood vessels and can cause blockage [52].

However, lab and animal studies have been unable to confirm if high fibrinogen causes heart disease [53, 54, 55, 56].

People with high fibrinogen levels are more likely to suffer from heart disease and have high cholesterol levels.

3) May Harm the Brain

High fibrinogen levels predict future cognitive decline, as well as the development of Alzheimer’s disease and dementia [57, 58].

Fibrinogen may increase brain deterioration in Alzheimer’s disease. Lab and rat experiments found that by binding to the abnormal brain plaque, fibrinogen increased damage to brain cells and blood vessels, while also promoting inflammation [59, 60, 61, 62].

High fibrinogen was also associated with active brain lesions in a case-control study of 58 patients with multiple sclerosis, possibly by disrupting the blood-brain barrier [63].

Fibrinogen also suppressed the brain’s ability to heal itself in lab experiments. It did this by inhibiting the regeneration of brain cells and the protective myelin sheaths that normally cover them [64, 65].

High fibrinogen levels may damage brain cells, disrupt the blood-brain barrier, and increase the risk of cognitive impairment and Alzheimer’s disease.

4) Associated with Diabetes

People with diabetes have higher blood fibrinogen levels [10, 66, 67].

High fibrinogen is also associated with diabetes along with heart disease, high cholesterol, or diabetic complications such as nerve damage [10, 66, 68, 69].

In a case-control study, 6 diabetic patients had high levels of both fibrinogen and glucagon, the hormone responsible for increasing blood sugar, but normal levels of albumin, a marker of insulin resistance. In other words, elevated fibrinogen may precede and possibly contribute to the development of diabetes [70, 71].

High levels of fibrinogen have been linked with diabetes and diabetic nerve damage.

5) May Promote Cancerous Tumors

High fibrinogen has been correlated with increased tumor growth, while also predicting poor clinical outcomes for patients with uterine, gastric, and kidney cancer [72, 73, 74].

Specifically, fibrinogen increased tumor cell adhesion and survival in the lung tumors of mice [75, 76].

It seems that the pro-tumor effect of fibrinogen is related to its inflammatory action, as well as inhibition of natural killer cells that typically stop cancerous growth [77, 78].

High fibrinogen may worsen cancer outcomes by increasing inflammation and promoting tumor growth.

6) Associated with High Blood Pressure

People with high blood pressure often also have elevated fibrinogen [9, 79].

A study of 143 people over 3 years found that increased fibrinogen after a stressful task predicted the later development of high blood pressure. People with stable fibrinogen levels did not develop high blood pressure. For unknown reasons, this effect was found exclusively in women [2].

High fibrinogen levels may increase the risk of high blood pressure, but possibly only in women.

Limitations

Most of the causal relationships between fibrinogen concentration and associated diseases remain unclear. More research is needed to make concrete conclusions about the effects of and effects on fibrinogen.

How to Lower Fibrinogen Levels

1) Cholesterol Medication and Diet

A meta-analysis of 22 trials and 2,762 participants found that fibrate cholesterol medication most effectively reduces fibrinogen compared to statins [80].

Specifically, bezafibrate lowered fibrinogen levels by an average of 40% in 2 double-blind placebo-controlled randomized trials with 50 and 100 participants [81, 82].

Foods that improve bad (LDL) cholesterol may also decrease fibrinogen levels, such as healthy fats and dietary fiber [83].

2) Drugs That Slow Blood Clotting

The anti-platelet drug ticlopidine also reduces fibrinogen concentration by 10 to 25% [84, 85, 86].

Diets rich in healthy fats and fiber, along with fibrate or anti-platelet drugs, effectively lower fibrinogen levels in most people.

3) Fish Oil

A meta-analysis (3 trials and 159 participants) found that fibrinogen decreased about 10% after supplementing with an average of 2.4 grams per day of omega-3 polyunsaturated fatty acids [87].

A double-blind cross-over study of 20 participants found that 6 grams per day of fish oil reduced fibrinogen by 20% after 6 weeks [88].

Another study of 25 participants found that three grams per day of fish oil for 4 weeks reduced fibrinogen blood levels by 3% on average [89].

4) Exercise

Multiple studies have found a correlation between regular exercise and low fibrinogen levels (surveys of 1,284, 2,398, and 3,967 participants, respectively) [90, 91, 26].

It seems that strenuous exercise, in particular, reduces fibrinogen: 2 studies of 156 (ten weeks) and 8 participants (one week) showed that fibrinogen decreased by 10 to 20% after intense workouts [92, 93].

Fish oil supplements and regular exercise both help lower fibrinogen.

5) Turmeric

Turmeric, a known remedy for inflammation and heart disease, decreased blood fibrinogen levels in a study of 30 subjects. Fibrinogen can also bind to curcumin (the active ingredient in turmeric) so that it does not degrade as quickly in the bloodstream [94, 95].

6) Traditional Chinese Medicine

The traditional Chinese medicines Quyu Jiedu, Xuebijing treatment, and XueFu ZhuYu decoction, reduced blood fibrinogen levels in 2 meta-analysis studies (15 RCTs with 1,364 patients; 11 RCTs with 686 patients) evaluating the use of traditional Chinese medicine for high blood pressure and chest pain from heart disease [96, 97].

7) Moderate Alcohol Consumption

Multiple studies (117 participants for 1 month; 20 participants for 6 weeks; 11 participants for 12 weeks) have shown that daily moderate alcohol consumption (wine or beer) reduced blood fibrinogen levels [98, 99, 100].

A glass of red wine a day for 40 days was seen to decrease blood fibrinogen levels by 8 to 15% in a clinical trial of 69 healthy adults [101].

8) Olive Oil

In a double-blind cross-over study, 6 grams of olive oil per day reduced blood fibrinogen levels by an average of 18% in 20 healthy volunteers after 6 weeks [88].

9) Nattokinase (Fermented Soybean)

A study of 12 healthy participants found that a single dose of 2000 nattokinase, an enzyme derived from fermented soybeans, significantly decreased blood fibrinogen levels after only 4 hours [102].

Adding more olive oil to your diet, having a glass of wine a day, and supplementing with turmeric or nattokinase may lower fibrinogen levels.

10) Hormone Replacement Therapy

Multiple studies (trial of 152 women for 1 year; 29 women for 6 months; surveys of over 5k women) have found that hormone replacement therapy may help reduce fibrinogen levels in postmenopausal women, though the effect appears to be minimal [103, 104, 105, 106].

12) B Vitamins

B vitamins, especially B6, B9, and B12, enhance the breakdown of fibrinogen by reducing the amino acid homocysteine [22, 24].

A study of 24 adults found that 5 mg/day of vitamin B9 for 4 weeks reduced blood fibrinogen levels by an average of 9% [107].

A 4-week regime of vitamin B6, B9, and B12 also reduced blood fibrinogen levels in 21 patients with sepsis [108].

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Irregular Fibrinogen Levels?

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Takeaway

Several lifestyle factors can increase your fibrinogen levels, including smoking, cold temperatures, eating a meat-heavy or high-carb diet, and vitamin B6 and iron deficiency. Women on birth control pills and people who are overweight also tend to have higher levels.

Fibrinogen levels normally rise in pregnancy and with aging. Additionally, people with genetic variants that increase homocysteine are more likely to have high fibrinogen levels.

Your body requires some fibrinogen for optimal health, but high levels can be harmful. If your fibrinogen levels rise too much, you will be at an increased risk of inflammation, heart disease, high cholesterol, diabetes, and dementia.

To lower your levels naturally, exercise on a regular basis and increase your dietary intake of olive oil, fish oil, and fiber. Vitamin B, turmeric, and nattokinase supplements may also help. If your fibrinogen levels are very high, your doctor may also prescribe fibrate or anti-platelet medication.

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