Niacin is not a nutrient that you hear too much about. But a new research study has people concerned about their intake.
Niacin is not a nutrient that you hear too much about. But a new research study has people concerned about their intake.
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Can these supplements help you lower cholesterol without drugs? (Nutrition Diva # 687)
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Hello, I'm Monica Reinagel, and you're listening to the Nutrition Diva podcast, a show where we take a closer look at nutrition news and research, answer your nutrition questions, so that you can feel more confident about your food and nutrition choices.
Today, we’re talking about niacin: how it affects your health, how much you need, and how much might be too much.
Nutrition Diva listener Donny writes: 'I have a question about Niacin (B3) intake. The RDA for Niacin is 16 mg with a UL of 35. I eat what I consider to be a pretty healthy diet but I usually end up in the 50-60 mg range. Do I need to be concerned about the long -term effects of constantly being over the 35 mg UL?”
Donny’s question may have been triggered by recent news coverage of a study suggesting a link between high levels of niacin and an increased risk of cardiovascular disease. However, I think the news coverage may have overstated the case a bit. And, in all fairness, the news media may have been led astray by a press release accompanying the publication, which glossed over many of the limitations that the researchers themselves noted in the actual paper.
First, let’s take a quick look at what the study found. Researchers working at the Cleveland Clinic measured the amount of certain niacin metabolites (compounds that excess niacin breaks down into) in the blood of over 1,000 heart patients. And those with the highest level of these compounds in their blood had higher risk of cardiovascular events. One of those compounds (called 4PY) had separately been found in mouse studies to promote vascular inflammation. And that’s meaningful because it suggests a plausible mechanism for how excessive niacin might promote heart disease.
Make no mistake: this is an important finding for researchers. However, the message that filtered through to the non-research world was that too much niacin could be a cause of heart disease. And that is miles away from what this study actually found.
First of all, this was a correlation, which doesn’t prove causation. Secondly, these were cardiac patients, so we certainly can’t assume that this correlation would hold true for the general population. But the biggest problem with trying to extract actionable advice out of this study is that they didn’t actually measure how much niacin people were eating. So there is no way to say what amount of dietary niacin is even correlated with increased risk. 100 mg/day? 1,000 mg/day? We have no idea.
Before we get into how much niacin is safe for you to be getting, let’s back up a minute and review what niacin (aka vitamin B3) does for us. Niacin is involved in converting the nutrients we eat into cellular energy; it also plays a role in cellular signaling, DNA repair, and maintaining healthy skin.
Once upon a time, niacin was popular as a natural way to lower your cholesterol. Supplementation with niacin reliably increases HDL levels and decreases LDL and triglyceride levels. Unfortunately, those improvements in cholesterol didn’t seem to reliably translate into a reduced risk of cardiovascular disease. Then again, it turns out that long-term niacin supplementation also increases insulin resistance–a different risk factor for heart disease–which could cancel out the cholesterol-lowering benefits.
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Niacin’s other big trick is acting as a precursor to NAD+, a co-enzyme that has provoked intense interest among longevity researchers (and longevity chasers). NAD+ levels in the body tend to fall off as we get older and there’s hope that propping them up might slow down the aging process.
However, niacin is not the most efficient way to increase NAD+ levels in the body. Other closely-related compounds like nicotinamide riboside (NR) and Nicotinamide mononucleotide (NMN) are more commonly used as supplements to increase NAD+ levels. And if that’s a train that you’re currently on, you’ll be reassured to know that this latest finding does not apply to those compounds.
So now, let’s talk about those recommended intakes and limits for niacin, that Donny mentioned. As he correctly notes, the RDA for niacin is 14 mg/day for adult women, and 16 mg/day for adult men. And most people get substantially more than that. For instance, a single 3-ounce serving of cooked turkey or salmon provides around 9-10 mg of niacin.
Meats like chicken, tuna, turkey, and salmon are among the highest food sources with smaller amounts in whole grains (like brown rice), legumes and seeds. But fortified foods, particularly cereals, contribute significantly to niacin intake. For example, fortified cereals can contain between 20-27 mg of niacin per cup. And finally, the addition of supplements can double or triple total niacin intakes compared to diet alone, especially among older individuals.
You can see how easily one could exceed the tolerable upper limit of 35 mg/day. However, if you’re starting to get nervous, it may reassure you to know that this upper limit is intended to avoid the flushing of the skin that can happen if you take a lot of niacin. Although you might find it mildly unpleasant, this flushing is a totally harmless and temporary phenomenon. More serious side effects, such as liver damage, have only been reported with amounts 100 times higher than that–there’s no way you’re going to get that much from a diet.
If headlines relating to the Cleveland Clinic study had you worried, I hope I’ve managed to set your mind at ease–at least in terms of the amount of niacin you are getting from foods. If you’re supplementing with high doses of niacin, it may be worth reevaluating your intake in consultation with your healthcare provider. (Don’t forget to account for the total amount you might be getting if you are taking multiple supplements.) If you’re taking niacin in an effort to reduce cholesterol, there might be other natural approaches that could offer the same or better benefits. I talked about some of them in episode 687.
If you have a question you'd like me to answer, you can email me at nutrition@quickanddirtytips.com or leave me a message at 443-961-6206.
I also wanted to invite you to check out my other podcast, the Change Academy, where we explore the art and science of creating positive behavior change. You can find it on all major podcast platforms.
Nutrition Diva is a Quick and Dirty Tips podcast and is supported by an incredible team: Brannan Goetschius, Nathan Semes, Davina Tomlin, Holly Hutchings, Morgan Christianson, and Kamryn Lacy.
That's all for this episode. Thanks for listening! I'll see you next week.