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.
Causes listed below are commonly associated with high fibrinogen. Work with your doctor or another health care professional to get an accurate diagnosis.
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) [13, 14, 15].
Smoking more seems to further increase fibrinogen, and fibrinogen levels do not return to normal until a person has refrained from smoking for about 15 years (11,059 participants; 118 participants) [15, 16].
Studies suggest oral contraceptives can increase fibrinogen levels, especially those with high estrogen concentration (randomized crossover study with 28 participants for 16 weeks; survey of 200 women) [17, 18, 19, 20].
Estrogen may elevate fibrinogen by increasing the expression of the FGG gene and production of the protein, as seen in rats .
As shown in a study with 194 participants, this effect was compounded in women who smoked while on birth control .
On the other hand, 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 [23, 24, 25, 26].
Multiple studies (895 participants; 1,002 participants; 7,329 participants) estimated that genes account for 34 to 46% of the individual variation in fibrinogen levels. A number of mutations associated with high fibrinogen levels are discussed here [27, 28, 29].
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 [30, 31, 32].
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 [13, 33, 34].
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) [35, 36, 37, 38].
Elevated fibrinogen of 206 Japanese emigrants in Hawaii was associated with more iron (red meat) and sugar consumption. This could implicate the prevalence of meat and high glycemic foods in the Western diet, which is also associated with heart disease .
A survey of 1.8k 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 lower fruit and vegetable intake and higher amounts of processed foods, seen in Western diets can increase chronic inflammation and fibrinogen levels .
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 .
Though a causal relationship has not been proved, the ability of exercise to decrease fibrinogen suggests body fat and chronic inflammation partially determine fibrinogen levels (87 participants; 3,967 participants) [42, 34].
Elevated fibrinogen levels increase the risk of blood clots, which can, in turn, contribute to an increased risk of heart disease.
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 [44, 45, 46, 47].
In a study of over 1.3k patients, high fibrinogen levels were also associated with a greater risk of developing heart disease over 18 months .
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 .
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 .
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 [55, 56, 57, 58].
Certain types of bacteria (Streptococcus) bind to fibrinogen in order to promote inflammation during infection .
Fibrinogen may increase brain deterioration in Alzheimer’s disease. Cell studies 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 [64, 65, 66, 67].
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 [69, 70].
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 .
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.
It’s likely that most of the above-described links between fibrinogen and health conditions are bidirectional. For example, fibrinogen increases when there is underlying inflammation (as an acute phase protein in inflammatory diseases, heart disease, cancer) and can also further increase inflammation.
High fibrinogen is often caused by an underlying health condition. The most important thing is to work with your doctor to find out what’s causing your low fibrinogen and to treat the underlying condition.
For example, if your fibrinogen is high due to an infection or an acute inflammatory process, it will return to normal once the underlying condition has resolved.
If you have a chronic condition such as rheumatoid arthritis, there may be little you can do to affect your levels [79, 80]. However, if your doctor tells you that high fibrinogen is increasing your risk of heart disease, you can make changes that will improve your levels of other heart disease risk factors, such as decreasing bad and increasing good cholesterol.
Discuss the additional lifestyle changes listed below with your doctor. None of these strategies should ever be done in place of what your doctor recommends or prescribes!
Foods that improve bad (LDL) cholesterol may also decrease fibrinogen levels, such as healthy fats and dietary fiber .
In addition, studies show there’s a link between diets high in red meat, sugar, and saturated fats and high fibrinogen levels. Therefore, eating more fruits and vegetables, and avoiding sugary, processed, and fast foods can help lower fibrinogen levels [39, 40].
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 [91, 92].
Lose weight if you are overweight, as obesity can increase fibrinogen levels, likely by increasing chronic inflammation in the body .
Multiple studies (117 participants for 1 month; 20 participants for 6 weeks; 11 participants for 12 weeks) have shown that daily moderate alcohol consumption (1 glass of wine or beer) reduced blood fibrinogen levels [94, 95, 96].
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 .
However, alcohol consumption can have negative effects on your health, so be sure to discuss the optimal amount of alcohol for your health with your doctor or another healthcare professional.
Initial studies suggest that the following supplements may help decrease fibrinogen levels in humans. However, more large-scale research is needed to confirm their effectiveness in the general population.
- Omega-3. 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 . In addition, studies in 20 and 25 participants found that fish oil reduced fibrinogen after 4 – 6 weeks [88, 99].
- 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 [100, 101].
- 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 [102, 103].
- Nattokinase. 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 .
- B vitamins, especially B6, B9, and B12, enhance the breakdown of fibrinogen by reducing the amino acid homocysteine [30, 32]. A study of 24 adults found that 5 mg/day of folate for 4 weeks reduced blood fibrinogen levels by an average of 9% . A 4-week regime of vitamin B6, B9, and B12 also reduced blood fibrinogen levels in 21 patients with sepsis .
Remember, always speak to your doctor before taking any supplements, because they may interfere with your health condition or your treatment/medications!
In addition to conditions such as injury, infections, or inflammation, several lifestyle factors can increase your fibrinogen levels, including smoking, eating a meat-heavy or high-carb diet, and vitamin B6 and iron deficiency. People who are overweight also tend to have higher fibrinogen 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 blood clots, inflammation, and heart disease.
To lower your levels work with your doctor to address any underlying health conditions. In addition, you can prevent increases in fibrinogen by exercising on a regular basis and eating a healthy diet. Increase your dietary intake of healthy fats (olive oil), omega-3s, and fiber. Some supplements may also help. If your fibrinogen levels are very high, your doctor may also prescribe fibrate or antiplatelet medication.