The perfume of the rose, campfire coffee in the morning, summer rain on city streets . . .
Malodorous taint of spoiled milk, fish that’s past its prime, gotta get that gas leak fixed . . .
Our noses warn us, entertain us, delight us, inform us. But if we lose our sense of smell, we lose something even more fundamental—the ability to taste our food.
Approximately 90 percent of our ability to taste food comes from our sense of smell, according to Alan Hirsch, MD, neurological director of The Smell and Taste Treatment and Research Foundation in Chicago. You need your sense of smell up and functioning if you want to appreciate the taste of chocolate or be able to tell the difference between an apple and an onion or simply enjoy your food.
Here’s an experiment. Close your eyes, hold your nose, and have a friend give you a small bit of apple and a small bit of onion. It’s likely you won’t be able to distinguish the two. That’s how important the sense of smell is to our sense of taste.
“When we talk about treatment for smell and taste, they’re usually one and the same thing,” says Dr. Hirsch.
We tend to lose our sense of smell as we age, says Dr. Hirsch. And that has a big impact on the foods we choose to eat. Many elderly people forgo vegetables simply because these foods no longer taste appealing, he says, and that’s because their sense of smell is no longer functioning fully. Green peppers, for example, have a sweet, aromatic aroma and a somewhat bitter taste, he explains. So people who can’t smell their food may stop thinking that peppers taste good. Multiply that by numerous other vegetables, and you have an unhealthy diet in the making.
But it’s not just aging that can rob us of our sense of smell. Other causes include head injury, nasal blockages, thyroid problems, even coronary bypass surgery, according to Dr. Hirsch. Long exposure to toxic fumes can also cause problems. It’s not unusual for a cold or flu to rob us temporarily of our sense of smell, but a number of chronic and infectious diseases can have a major and sometimes lasting impact. Dr. Hirsch estimates that some 15 million Americans have “olfactory abnormalities.”
If you experience the loss of your sense of taste or smell, you should discuss the problem with your doctor, as this can be a sign of a more serious condition. It’s possible that with the right treatment, these important senses can be restored.
Several nutrients can sometimes prove helpful in improving or even restoring the sense of smell and taste.
Research has found that the combination of the B vitamin folate and the nutrient N-acetylcysteine (NAC) can help improve the sense of smell for some people, says Dr. Hirsch. NAC is a modified form of the amino acid cysteine and is readily available as a supplement.
“I don’t have a good rationale for why it works,” says Dr. Hirsch. “We were using it to study mild cognitive impairment and found that it improves the sense of smell.” Alzheimer’s disease causes the memory problems and mental confusion that doctors call cognitive impairment. And people with Alzheimer’s also experience a diminished ability to smell things.
The best form of folate to use to improve the sense of smell, says Dr. Hirsch, is L-methyl folate, and to get this, you need a prescription. He suggests taking 5.6 to 6 milligrams. You can combine this with 600 milligrams of over-the-counter NAC, he says.
Researchers stumbled upon the effectiveness of the nutrient phosphatidylcholine in improving the sense of smell when they were studying the nutrient as a therapy for Alzheimer’s, reports Dr. Hirsch.
“I’m not sure it helped the Alzheimer’s any,” he says, “but it improved the olfactory response.” In the study, 40 percent of participants experienced an improved sense of smell. One of the studies researchers did was actually ruined because they were using a nutrient preparation that had a really bad smell, says Dr. Hirsch. As study participants started getting their sense of smell back, they started refusing to take the nutrient and began dropping out of the study.
In order to get the smell-improving benefits, you need to take a large amount of phosphatidylcholine, says Dr. Hirsch. He recommends 3,000 milligrams three times a day. It’s more convenient to take it in liquid form. (And the supplement that you purchase over the counter does not have a bad smell.)
Studies have shown that the B vitamin thiamin “seems to have some efficacy,” says Dr. Hirsch. In some individuals, thiamin is “incredibly effective” in improving the sense of smell, he says. He suggests taking 100 milligrams daily.
“Back in the 1960s, a number of studies came out showing that vitamin A injections improved olfactory function,” says Dr. Hirsch. There is a certain amount of retinol (natural vitamin A) in the olfactory bulb, he says, which is “hypothetically why vitamin A may improve smell.” The olfactory bulb is a portion of the brain that interprets smells.
Large doses of injected vitamin A were used in the study. You could try asking your doctor for a couple of vitamin A injections, says Dr. Hirsch, but your doctor would likely decline. As an alternative, says Dr. Hirsch, you could try taking 10,000 IU of vitamin A twice a day for 3 months. If it’s going to work, you should know by this time. This is a high dose of vitamin A, so you should discuss it with your doctor before taking this much.
A number of years ago, several case reports suggested that zinc might sometimes be helpful in improving the sense of smell, but since then studies looking at its effectiveness have been disappointing, says Dr. Hirsch. Despite the negative results from those studies, zinc “sure seems to work” for some people, he notes.
Why would he say something like that? Through the years, says Dr. Hirsch, his foundation has received a number of calls from people who had lost their sense of smell following cardiac surgery. Before the research came in on the other nutrients recommended in this chapter, the foundation didn’t really have any other nutrients to recommend. So they mentioned that the earlier case studies had found that zinc is sometimes helpful. Some of the cardiac patients decided to give zinc a try. Then some of these people started reporting back that zinc had been helpful.
If you’d like to give zinc a try, there are two possible approaches suggested by the earlier case reports, says Dr. Hirsch. One possible approach would be to take 220 milligrams four times a day for 3 months. Another possible approach would be to take 140 milligrams of zinc gluconate once a day for 4 months. In both cases, this is an extremely high dose of zinc.
Zinc can be toxic at higher doses if taken for extended periods of time. So if you want to try this therapy, make sure you discuss it with your doctor first, and do make sure that you stop the therapy whether or not it works after the allotted period of time or that you have your doctor’s permission to extend the trial for a short time. Taking this much zinc could deplete your body of copper, an essential nutrient. Experts generally recommend taking 1 to 3 milligrams of copper as well whenever you’re taking high doses of zinc.
One note of caution here: There have been a number of case reports of people losing their sense of smell after using inhaled zinc products designed to ease cold symptoms, says Dr. Hirsch. He advises against inhaling zinc in any form.
If you are experiencing problems with your sense of smell or taste, you should see your doctor to determine the cause. This is a symptom that should not be ignored. Also, discuss any of these nutrients with your doctor before deciding whether to take them. All of these therapies are short-term approaches. If they’re going to work, you’ll know after a few months. Taking them for a longer period of time will not be helpful.
Copper* |
1 to 3 milligrams |
Folate† |
5.6 to 6 milligrams in the form of prescription L-methyl folate |
N-acetylcysteine† |
600 milligrams |
Phosphatidylcholine |
3,000 milligrams, three times a day |
Thiamin |
100 milligrams |
Vitamin A |
10,000 IU, two times a day for 3 months |
Zinc* |
220 milligrams, four times a day for 3 months OR 140 milligrams in the form of zinc gluconate once a day for 4 months |
*Experts recommend taking a small dose of copper along with high amounts of zinc. Do not take high therapeutic doses of zinc without your doctor’s permission.
†As a therapy to possibly improve the sense of smell, folate and N-acetylcysteine need to be taken together.