Stimulant medicines are the most common way doctors treat attention deficit hyperactivity disorder (ADHD). But you might be looking for ways to help with your ADHD symptoms without the possible side effects of stimulants or for other reasons. The idea that amino acid supplements might help with ADHD has been around for decades. You can find articles online suggesting that they do. But these often don’t come from reputable sources. You might also see amino acid supplements for sale that say they’ll help your brain or attention in different ways. The question is: Is there good reason to think amino acids might actually help with adult ADHD?
What Are Amino Acids?
Amino acids are the building blocks of proteins. There are 20 different ones your body needs. Your body can make 11 of them. But you need to get the other nine from your diet. Those nine you need to get from your diet are called essential amino acids. That’s not really because you need them more than the others. It’s because your body doesn’t make them, so you need to get them from somewhere else.
The nine essential amino acids are:
- Histidine
- Isoleucine
- Leucine
- Lysine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
Essential amino acids do lots of different things in your body. Some of them are especially important in the brain. They help to make chemicals that act as messengers in the brain. For example, you need phenylalanine to make these brain chemicals:
- Dopamine
- Epinephrine
- Norepinephrine
You also need tryptophan to make the brain chemical called serotonin. Histidine helps make histamine, which plays a role in the brain and in the immune system. Most of the time you don’t need to worry about having enough of the amino acids your body makes. The 11 nonessential amino acids your body makes are:
- Alanine
- Arginine
- Asparagine
- Aspartic acid
- Cysteine
- Glutamic acid (also known as glutamate)
- Glutamine
- Glycine
- Proline
- Serine
- Tyrosine
There are some amino acids your body doesn’t usually need. But sometimes you might if you are sick, stressed, or something else is wrong. They’re called conditional amino acids and include seven of the nonessential amino acids plus one other. These include:
- Arginine
- Cysteine
- Glutamine
- Tyrosine
- Glycine
- Ornithine
- Proline
- Serine
Do You Need to Take Amino Acid Supplements?
Not usually, no. Your body makes 11 of them by itself. The other nine essential amino acids generally are easy to get from foods you eat. You don’t need to have amino acids in every meal. But you should get a good mix of them over time.
Any food that has protein in it will have amino acids. Foods with all nine essential amino acids include:
- Meat
- Poultry
- Eggs
- Fish
- Dairy
- Soy
- Quinoa
- Buckwheat
Foods with some essential amino acids (but not all) include:
- Nuts
- Seeds
- Beans
- Rice
- Grains
If you don’t eat meat or other sources of animal protein, it’s a good idea to make sure your diet includes all of the nine essential amino acids. If you’re getting proteins and amino acids from a variety of sources, there’s a good chance it will. It isn’t usually necessary to take supplements to get enough amino acids. But some people take them because they think they help in different ways.
Do Adults With ADHD Have Changes in Amino Acids?
If adults with ADHD need more of certain amino acids, you’d think they might show changes in them that could be corrected with food or supplements. There are more studies on ADHD in kids than in adults. There’s not much data on amino acid changes in adults with ADHD. But most adults with ADHD probably had it when they were kids, too. Contrary to what people used to think, most kids with ADHD don’t really grow out of it either. So studies in kids with ADHD might be relevant to what happens in adults. Several studies have looked at amino acids in people (mostly kids) with ADHD.
A 2011 study looked at the amino acid tyrosine and two others. Researchers thought tyrosine might be important because you need it to make dopamine and norepinephrine in the brain. They also noted that you need tryptophan to make serotonin. Problems moving amino acids in the body had been linked to some other conditions, including schizophrenia and autism. So they looked to see if boys diagnosed with ADHD had any signs of problems moving amino acids around in the body. Since you can’t exactly look at this in the brain, they looked instead in cells from skin called fibroblasts. They looked at movement of three amino acids:
- Tyrosine
- Tryptophan
- Alanine
They did find a significant difference in movement for tryptophan but not the other two. (There was more alanine movement, but it wasn’t significant.) While the findings were in skin cells, they said it suggested similar things were happening in the brain. The findings suggested that problems moving tryptophan could mean the kids with ADHD had less serotonin. They said those changes might cause other differences also. While the findings are suggestive, they really couldn’t say for sure what it means in kids or adults with ADHD.
Another study looked at amino acids glutamate and glutamine in adults with ADHD. Researchers said there’d been signs of trouble with glutamate signals in people with ADHD. One question was whether those changes had to do with ADHD or the stimulants people with ADHD often take. So they looked at adults with ADHD who weren’t taking medicine.
And they did find people with ADHD had less glutamate and glutamine. They also found that lower glutamate and glutamine tended to happen in adults with worse ADHD symptoms. It suggested to them that this could be a way to treat ADHD in adults. Note that these are amino acids that your body usually makes all by itself. Normally you don’t need to get glutamate or glutamine from your diet or supplements.
Other studies looking at amino acids in blood have been more mixed. A 2016 study looked at 83 kids with ADHD and 72 without. They found normal levels of three amino acids (tryptophan, tyrosine, and phenylalanine) in kids with ADHD. Kids with ADHD also had a normal amount of protein in their diets. But the researchers said it would make sense to look for differences in amino acid transport in the body to see if that could explain differences in brain chemistry.
A 2021 study noted that there had been evidence of amino acid differences in ADHD from other reports. They looked again and did find some differences in blood levels of amino acids. They found kids with ADHD had less:
- Histidine
- Glutamine
- Proline
They also had more:
- Aspartate
- Glutamate
- Hydroxyproline
They concluded that these changes might have something to do with ADHD. But they said further study was needed to see if that was true and how it worked. So, overall, there’s some evidence that differences in amino acid levels or the way amino acids move around the body might have a role in ADHD. But there’s still a lot scientists don’t know and it’s not clear what it means for treating ADHD.
Do Amino Acid Supplements Help ADHD?
If amino acids might have something to do with ADHD, does it help to take amino acid supplements? Some studies have also looked at this, again mostly in kids not adults. A study from 1986 looked at this in 14 kids with ADHD for a week. Kids took tyrosine, tryptophan, an ADHD medicine called amphetamine, or a placebo without anything in it. They asked teachers and parents if they could tell any difference in behavior. They found tyrosine made no difference that anyone noticed. Tryptophan didn’t either as far as teachers could tell. But parents thought it made ADHD symptoms better. Note that this study is very small and brief, so it’s hard to be sure of anything from it.
A 2011 study included 85 kids with ADHD who took amino acids needed to make serotonin and dopamine for several weeks. It found improvement in more than 70% of them. But this study was retracted in 2020 after experts found the researchers hadn’t done the study the right way. The researchers also didn’t provide all the data the way they should have. So while you can still find this study and it might be part of where the idea that amino acids help ADHD is out there, the data in it can’t be trusted.
A 2016 study tested whether tyrosine (needed to make dopamine) helped with working memory. It found that it did. It also suggested that the amount it helped depended on a person’s genes. While this study suggests that certain amino acids might help your brain, it didn’t look at what happens in adults with ADHD.
So overall, there’s some reason to think ADHD might have something to do with changes in amino acids or how they move in the body, but evidence showing that taking amino acid supplements helps ADHD is lacking. Most people have enough amino acids without special diets or supplements. If the trouble is related to amino acid transport in the brain, getting extra amino acids in your food or from supplements might not even help.
A Word on Supplements
Most supplements are reasonably safe to take as long as you don’t take too much. But they can have risks, and it’s always a good idea to check with your doctor first. Chances are it’s OK to try an amino acid supplement if you want to, even if evidence it helps your ADHD isn’t strong.
You should always keep in mind that supplements aren’t regulated in the same way medicine is. Supplements aren’t meant to “treat, diagnose, prevent, or cure disease.” So companies selling them shouldn’t make any claims that they’ll help with your ADHD. If a clinic or company is selling you an amino acid supplement with claims it will help your ADHD, you should have doubts about them and the product they are selling.
