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Niacin, also known as vitamin B3, was the first drug ever prescribed to treat high blood cholesterol levels. Niacin can significantly affect how cholesterol acts in your body, reducing the production of LDL cholesterol, or “bad” cholesterol, and improving the function of HDL cholesterol, the “good” cholesterol.
While niacin improves your cholesterol overall, unfortunately, this does not translate to a reduced risk of heart attacks, strokes, or death. Other cholesterol-lowering medications, such as statins, reduce these risks and are now favored over niacin. Niacin is now largely used for improving the cholesterol profile in patients who cannot tolerate other medications.
Niacin, also called nicotinic acid, comes in another form called nicotinamide.¹ While both forms are sources of dietary niacin, only nicotinic acid affects your cholesterol levels.
Niacin plays an important part in many bodily processes, which makes it an important nutrient in your diet. Most people get enough niacin from their diet, including from animal and plant foods. Your body can also make some of its own niacin by using an amino acid called tryptophan.
A deficiency in niacin leads to the development of pellagra,² a disorder seen in developing countries when people have food sources limited to one or two crops. Those crops, such as maize or millet, contain no niacin and very little tryptophan. This disorder presents as skin rashes after exposure to sunlight. Over time these rashes thicken and crust over.
Pellagra also affects the gut, commonly causing discomfort and diarrhea, and the nervous system, which can cause dementia. Pellagra is considered eradicated in industrialized countries, where people usually have easy access to multiple food sources, including animal products that contain niacin.
The importance of niacin in the body, and the long list of processes it plays a role in, means everyone will benefit from niacin in their diet. If you take niacin in the form of prescription medications or supplements, your intake will be much higher than that obtained from food.
People who do not have access to food sources that contain niacin, such as those who live in famine-like conditions, would find immense benefit in a niacin supplement to help prevent or treat pellagra.
In a first-world country, where pellagra is rare, you might benefit from taking a higher dose of niacin if you have high blood cholesterol levels, often called hypercholesterolemia or hyperlipidemia.
This is because niacin is a drug used to improve cholesterol levels, but only if the patient cannot tolerate other medications (due to the risks associated with taking supplementary niacin).
Hyperlipidemia is a well-established major risk factor for the development of atherosclerosis, a form of heart disease. The longer you are exposed to high cholesterol, the higher your levels are, and the greater your risk of developing heart disease.
Given the relationship between high cholesterol and your risk of heart disease, it makes sense that lowering your blood cholesterol levels will reduce your risk of developing the disease or stop it from progressing if you already have it.
Your doctor can encourage you to reduce your cholesterol levels in multiple ways. These include lifestyle changes such as alterations to your diet and exercise level or using cholesterol-lowering medications.
Prescription doses of niacin act within the body to reduce the LDL cholesterol and increase the HDL cholesterol levels in your blood. LDL cholesterol is often called “bad” cholesterol as it leads to the buildup of cholesterol in your arteries, the tubes in your body which carry blood from your heart to your organs and tissues. This buildup, also called plaque, leads to atherosclerosis and heart disease.
HDL cholesterol works reversely to LDL cholesterol, which is why it is often called “good” cholesterol. HDL cholesterol helps to remove the buildup of cholesterol in your arteries and takes it back to the liver. One of the jobs of our liver is to break down cholesterol.
High levels of HDL are considered to help protect against the development of heart disease.
Niacin is especially good at raising HDL cholesterol levels in your body, which suggests it should be effective at protecting against the development of atherosclerosis and heart disease. However, there is moderate evidence³ that niacin does not reduce the number of myocardial infarctions, suggesting that niacin therapy doesn’t necessarily lead to beneficial outcomes.
Some reasons for this surprising result may include:
High amounts of HDL cholesterol may not be as protective against heart disease as people think.
High doses of niacin produce some negative side effects. This means that people are more likely to stop taking their medication because they are deterred by the side effects.
If you are considering taking niacin, you should talk to your doctor about it. Niacin is usually reserved for patients who cannot tolerate other forms of cholesterol-lowering medications. Niacin can have some serious side effects, so it's not a drug you want to start taking without consulting a medical professional.
There are different forms of niacin medications:
Immediate release: Designed to be taken two to three times per day with meals. This method is not commonly used anymore due to the inconvenience of taking it multiple times throughout the day and because of the side effects, mainly flushing.
Extended-release: This form is taken once daily, which is more convenient, but side effects such as flushing are common. There is also a low risk of liver toxicity, but it is generally considered safe.
Sustained release: This form was developed to reduce the negative side effects but is no longer used due to the toxic effects on the liver.
Niacin is also available in supplement form, which you can get from your health store instead of your doctor.
A word of caution: Supplements are not subject to the same regulations and standards as pharmaceutical drugs, so you need to be careful about what they contain. As mentioned, there are two forms of niacin:
If you are taking it for cholesterol-lowering or heart-protective reasons, ensure your niacin supplement contains nicotinic acid. Nicotinamide will not have the same effects.
The recommended daily allowance for niacin in your diet for adults 19 years or older is 16mg for men and 14mg for women. The tolerable upper limit (the highest amount you can have without experiencing any negative side effects) is 35mg.
The dosage of prescription niacin is much higher than this, being 1–4g per day, which equates to 1,000–4,000mg. Because this is well above the upper limit, some side effects are associated with these high doses.
It’s important to talk to your health professional before taking niacin. In most cases, niacin should only be taken when no other cholesterol-lowering medication is tolerated.
Due to the prescription doses of niacin being well above the upper limit of 35mg, they come with side effects. These include:
Flushing: This is probably the most common symptom of niacin medications and manifests as a red flush over the face, arms, and chest. It is usually accompanied by stinging or burning sensations and sometimes headaches and blood rushing in your ears. Though these symptoms are harmless and go away with time, it is common to want to stop niacin treatment because of this flushing.
Gastrointestinal discomfort: This is a side effect of extended-release niacin that involves general gut discomfort.
Liver toxicity: This was a side effect of the sustained release of niacin, leading to this medication no longer being used. There have also been recorded cases of liver toxicity from other niacin medications and extremely high doses, reaching 9g per day. In severe cases, niacin taken in amounts toxic to the liver has resulted in the need for liver transplants.
Glucose intolerance: Niacin can have a negative impact on the blood sugar control of healthy, non-diabetes patients, so taking niacin could contribute to the development of diabetes. Interestingly, this effect was not as strong in people who already had diabetes. This effect has been recorded with high doses of 3g per day.
Ocular effects: In rare cases, niacin has been recorded to cause some reversible damage to people's vision. Blurred vision and cystoid macular edema are among these effects. These effects are dose-dependent, appearing at higher doses.
Due to these side effects, some risks come with niacin therapy, mainly, the risk of liver damage if you already have liver-related health problems. There is also the risk for people with pre-diabetes and diabetes that lowered blood glucose control may cause their condition to worsen.
Niacin is widely available in lots of animal and plant foods. Animal foods such as meat, fish, and poultry contain relatively high amounts of niacin at 5–10mg per serving. Plant sources include nuts, legumes, and grains, which contain around 2–5mg per serving.
The niacin in animal foods is more bioavailable than in plant foods. Bioavailability measures the availability of a nutrient to the body after digestion. So, your body will be able to use more of the niacin in the meat you ate and less of the niacin in nuts, for example.
In the United States, niacin is also added to staple foods like bread and cereal to fortify them. This is a public health strategy to ensure everyone is getting niacin in their diet to reduce the risk of pellagra.
The amount of niacin you can get from food will never be enough to see the effects that high-dose niacin medications produce. So, niacin from food will never be enough to lower your blood cholesterol levels.
Niacin is a B vitamin found readily in foods, a dietary supplement, and a pharmaceutical drug prescribed to improve cholesterol levels. While niacin has been proven to lower “bad” LDL cholesterol and increase “good” HDL cholesterol, studies have shown that this does not lead to reduced heart attacks, strokes, and death rates.
It also comes with several adverse side effects ranging from flushing and blurry vision to glucose intolerance, risk of diabetes, and liver toxicity. You should consult a medical professional to discuss whether niacin supplements or medication is right for you.
Niacin | NIH: National Institute of Health
Triglyceride lowering drugs (2021)
Prevention and treatment of high cholesterol (Hyperlipidemia) | Heart Attack and Stroke Symptoms
What is atherosclerosis? | Heart Attack and Stroke Symptoms
Cholesterol medications | Heart Attack and Stroke Symptoms
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