By Megan Nunn, PharmD 

Updated on November 15, 2023

 Medically reviewed by Suzanne Fisher, RD

窗体顶端

Oxidized nicotinamide adenine dinucleotide (NAD+) is crucial to over 500 enzyme reactions in your body. NAD+ can be derived from tryptophan.

Levels of NAD+ are reduced with aging and conditions like the following:

• Diabetes

• Inflammation

• Heart disease¹

This article covers the latest evidence for using NAD+ supplements and some safety concerns to be aware of if you decide to use them.

What Is NAD+?

NAD+ is a coenzyme that is important for many pathways in the body, including the following:¹

• Cellular energy

• DNA repair

• Hormone signaling

• Inflammation

It also helps maintain metabolism and circadian rhythm (the 24-hour internal clock regulating sleep cycles).²

Significantly, signaling proteins called sirtuins require NAD+ to regulate age-related changes and extend life span.³

Is NAD+ the Same as NADH?

Nicotinamide adenine dinucleotide, or NAD, can come in two forms, as follows:

• NADH, "reduced" NAD, meaning it has an extra electron

• NAD+, "oxidized" NAD, meaning it lost an electron⁴

NADH is different from NAD+.

 Taking a supplement in the kitchen close up.

vorDa / Getty Images

Do Foods Contain NAD+?

Several precursors (a substance that can form other substances) can increase NAD+ levels in the body. You can get these precursors through supplements or foods. Precursors that increase NAD+ levels include the following:¹

• Tryptophan

• Nicotinic acid (also known as niacin or vitamin B3)

• Niacinamide (another form of vitamin B3)

• Nicotinamide mononucleotide (NMN), the Food and Drug Administration (FDA) has considered NMN to be an investigational drug and not a supplement⁵

• Nicotinamide riboside (NR)

Good food sources of tryptophan and niacin include the following:

• Beef

• Chicken

• Fish

• Turkey⁶⁷

You can also find some niacin in the following vegetarian foods:

• Dairy products

• Enriched grains

• Fruit

• Legumes

• Nuts

• Seeds

• Soy products

• Vegetables

• Whole grains⁷

Uses

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

Because levels of NAD+ decrease with aging, it's theorized that supplements that boost NAD+ could slow the effects of aging and extend life span.¹

NAD+ and its precursors have been studied in preclinical trials (using cells in test tubes or animal models) for the following conditions:⁸

• Alzheimer's disease⁸

• Amyotrophic lateral sclerosis (ALS)⁹

• Huntington’s disease (HD)⁹

• Parkinson’s disease (PD)⁹

• Vascular dementia⁸

• Cognitive decline⁸

• Diabetes⁸

• Obesity⁹³

• Heart protection¹⁰

• Stroke⁸

• Traumatic brain injury⁸

• Fertility¹¹

• Glaucoma¹¹

• Ocular (eye) degeneration¹¹

• Metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as nonalcoholic fatty liver disease or NAFLD)⁹

Results seen in animal or lab studies may or may not be replicated in humans. NAD+ is not currently recommended for any of these conditions.

NAD, NMN, and NR have been studied in human clinical trials for the following conditions:

• Parkinson's disease¹²

• Prediabetes¹³

• Addiction¹⁴

• Inflammation¹⁵

Many of these trials were very small and included 30 or fewer people. Large-scale studies are needed before these supplements can be recommended.

Dosage

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.

There aren't many studies on the effects of NAD+ supplements in humans. So, it is unknown how to dose these supplements. Dosage will depend on your product and what you use it for.

Tryptophan, NMN, NR, and niacin or niacinamide food sources or supplements can increase NAD+.⁹

And keep in mind that optimal dosing or duration of NAD+ supplements have not been established yet.¹

Clinical trials have used the following doses:

• 250 milligrams (mg) of NMN daily for metabolic benefits in females with prediabetes¹¹

• 1,000 mg of NR daily to improve body composition in people with obesity¹⁶

• 1,000 mg of NR daily for Parkinson's disease¹²

In the United States, the Food and Drug Administration (FDA) does not regulate supplements the way it regulates prescription drugs. That means some supplement products may not contain what the label says. When choosing a supplement, look for third-party tested products and consult a healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.

Side Effects

Your provider may recommend you take an NAD+ supplement to slow the effects of aging or for another reason. However, consuming one of these supplements may have potential side effects that may be common or severe. 

Some side effects associated with NAD+ supplements include the following:

• Flushing¹

• Itching¹

• Elevated liver enzymes¹

• Liver toxicity¹

• Nausea¹¹

• Headache¹¹

• Low platelet levels¹⁷

• Leg cramps¹⁸

These side effects may vary depending on which NAD+ supplement you choose. NMN and NR might be better tolerated than other NADs, although fewer studies about their effects exist.¹

While not much is known about the severe side effects of these supplements, some animal studies have shown that NR, in particular, may cause tumors.¹⁹ However, whether this effect is the same in humans is unclear since results in animal studies don't always translate to those in humans.

Precautions

Since most of the evidence for NAD+ supplements comes from animal studies, not a lot is known about the effects of these supplements in humans.

Do keep the following precautions in mind when using NAD:

• Severe allergic reaction: Avoid using NAD+ supplements if you have a known allergy to it or its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

• Pregnancy: NAD+ supplements are not recommended during pregnancy due to a lack of safety data in humans.

• Breastfeeding: Due to a lack of safety data in humans, NAD+ supplements are not recommended during breastfeeding.

• Children: Due to a lack of safety data in humans, NAD+ supplements are generally not recommended for children. That said, one long-term study concluded that nicotinamide (a form of B3) at a dose of 25 to 50 mg per kilogram (kg) of body weight (mg/kg) was safe for children. As a best practice, discuss the use of any supplements you're considering with your child's pediatrician.

• Other modifications: People with liver or kidney problems should be cautious when using NAD+ supplements due to possible side effects on these organs.¹⁷ And there's not enough evidence to know if NAD+ supplements are safe for people with cancer or inflammatory disorders like rheumatoid arthritis.¹⁸

Interactions

NAD supplements may interact with the following medications:

• Antidepressants: These medicines may lower the level of NAD in the body and make supplements less effective.²⁰

• Insulin: NAD+ supplements may increase¹³ or decrease insulin sensitivity, meaning you might need a different amount of insulin to get the same effect.¹⁷

• Other supplements: More data are needed. However, other supplements that act on various pathways involved in the aging process may increase the effects of NAD+ supplements.¹⁹ A few examples of these supplements are curcumin, quercetin, and coenzyme Q10 (CoQ10).

It is essential to carefully read a supplement's ingredients list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

Summary

NAD+ is essential for regulating metabolism and circadian rhythm. As we age, levels of NAD+ decline. Reduced levels of NAD+ are associated with conditions like mental decline, diabetes, and heart disease.

Niacin, niacinamide, NMN, and NR can all boost levels of NAD+ in the body. In theory, these supplements could slow the effects of aging and combat diseases, but more research is needed.

Without strong clinical trials in humans, informed decisions cannot be made about the risks versus benefits of various NAD+ supplements.