Triglycerides are the main form of fat used by the body for energy. High-density lipoprotein (HDL) cholesterol, often called the “good” cholesterol, moves excess cholesterol from the bloodstream back to the liver for disposal. While high triglycerides and low HDL is a common cardiovascular risk pattern, the combination of low triglycerides and low HDL is less frequent and requires closer examination. This specific lipid profile suggests a unique underlying biology or lifestyle factor.
Defining Low Triglycerides and Low HDL
A lipid panel test measures fat concentration in the blood, expressed in milligrams per deciliter (mg/dL). For triglycerides, a fasting level below 150 mg/dL is normal, and levels below 90 mg/dL are optimal. However, a very low triglyceride level, often defined as below 40 mg/dL, may prompt medical investigation for an underlying issue.
The definition of low HDL cholesterol differs between sexes. For men, an HDL level under 40 mg/dL is classified as low, and for women, a level under 50 mg/dL is considered low. Levels of 60 mg/dL or higher are protective against heart disease. This profile involves an HDL level low enough to be a risk factor, combined with an unusually low triglyceride level.
Potential Underlying Causes for the Combination
The simultaneous occurrence of low triglycerides and low HDL is atypical. These two lipid components usually move in opposite directions, with high triglycerides paired with low HDL being the common pattern associated with poor metabolic health. When both are low, the cause is often systemic, affecting the body’s ability to produce or absorb fats.
One category of causes involves severe malnutrition or malabsorption disorders, such as untreated celiac disease or inflammatory bowel disease. The body struggles to absorb dietary fats and fat-soluble vitamins, leading to a deficit of the building blocks needed for triglycerides and HDL particles. Endocrine disorders like hyperthyroidism can also accelerate metabolism, abnormally suppressing lipid levels, including triglycerides.
In rare instances, the combination points toward specific genetic conditions that interfere with lipoprotein production. Familial Hypobetalipoproteinemia (FHBL), for example, is a genetic disorder resulting in lifelong low levels of both cholesterol and triglycerides. These conditions involve mutations that impair the assembly and secretion of fat-carrying particles from the liver and intestines. This leads to a shortage of the building blocks required for healthy HDL production, rooted in fundamental metabolic pathways rather than lifestyle.
Health Implications of the Specific Lipid Profile
When triglycerides are low but HDL is also low, the primary concern is the low HDL level as a driver of long-term risk. Low HDL is an independent risk factor for atherosclerosis, the buildup of plaque in the arteries. This occurs because the body’s ability to clear excess cholesterol is impaired, increasing the lifetime risk of coronary heart disease and ischemic stroke.
The ratio of triglycerides to HDL is often used as a marker of metabolic health, where a low ratio is generally favorable and suggests good insulin sensitivity. However, when the triglyceride level is pathologically low—below 40 mg/dL—it may signal a separate, non-cardiovascular systemic illness. In patients with advanced conditions like heart failure or certain autoimmune diseases, very low triglyceride levels can be a marker of inflammation or declining metabolic reserves, reflecting a poor prognosis unrelated to the protective effect of low triglycerides alone.
Furthermore, the quality of the HDL particle, known as HDL function, may be compromised even if the number is within a near-normal range. HDL’s ability to effectively perform reverse cholesterol transport can be impaired by chronic inflammation or oxidative stress. Therefore, in this specific lipid profile, the low HDL level is the most direct signal of increased cardiovascular vulnerability, while an extremely low triglyceride number warrants a thorough medical investigation for an underlying non-lipid-related condition.
Lifestyle Adjustments to Optimize HDL
Since low HDL presents the most significant cardiovascular risk in this profile, lifestyle changes are targeted to raise its concentration. Aerobic exercise is one of the most effective non-dietary ways to increase HDL, with benefits seen from as little as 60 minutes of moderate-intensity activity per week. Regular physical activity stimulates the production of enzymes necessary for HDL particle formation and function.
Dietary adjustments should focus on replacing saturated and trans fats with monounsaturated and polyunsaturated fats. Incorporating sources like olive oil, avocados, nuts, and fatty fish high in Omega-3 fatty acids can favorably influence HDL levels. These healthy fats provide components for lipid transport without promoting inflammatory patterns.
Cessation of smoking is another powerful intervention, as tobacco smoke chemicals can directly impair the function of the Apolipoprotein A1 protein, a main component of HDL. Quitting smoking can lead to an increase in HDL levels, sometimes by up to 10%. Additionally, achieving a moderate weight loss, even a modest reduction of 5 to 10 percent of body weight, can contribute to raising HDL concentrations and improving overall lipid metabolism.