According to Gram Research analysis, a study of 9,328 American adults found that eating more vitamin A and D is associated with better lung function, with vitamin D showing the strongest connection—each additional microgram per day linked to about 3.72 milliliters more lung capacity. However, this cross-sectional study can only show associations, not prove these vitamins prevent lung disease or that supplements would help.
A large study of over 9,000 American adults found that eating foods rich in vitamins A and D may be connected to better lung function. Researchers looked at what people ate and measured how well their lungs worked using breathing tests. They discovered that people who got more vitamins A and D from their diet had slightly better lung capacity and airflow. However, the study only looked at one point in time, so it can’t prove that these vitamins actually cause better lung health—just that they seem to go together. More research is needed to understand if eating more of these vitamins could actually improve your breathing.
Key Statistics
A 2026 cross-sectional analysis of 9,328 American adults found that vitamin D intake was positively associated with lung capacity, with each additional microgram per day linked to a 3.72 milliliter increase in forced vital capacity.
According to a 2026 study of over 9,000 adults from the National Health and Nutrition Examination Survey, vitamin A and D showed inverted U-shaped relationships with lung function, suggesting optimal intake thresholds at 958 micrograms per day for vitamin A and 11.95 micrograms per day for vitamin D.
A 2026 analysis of 9,328 participants found that vitamins A and K were positively associated with airway inflammation markers (FeNO), with vitamin A increasing FeNO by 1.1 parts per billion per unit increase in intake.
Research reviewed by Gram found that in a cross-sectional study of 9,328 adults, the associations between vitamins A and D and lung function were significantly stronger among overweight individuals compared to normal-weight participants.
The Quick Take
- What they studied: Whether eating foods with vitamins A, D, E, and K is connected to how well people’s lungs work and how inflamed their airways are
- Who participated: 9,328 American adults of various ages, races, and backgrounds who participated in a national health survey between 2007 and 2012
- Key finding: Adults who ate more vitamin A and D had better lung capacity and airflow measurements. For every extra microgram of vitamin D eaten per day, lung capacity increased by about 3.72 milliliters on average.
- What it means for you: Eating foods rich in vitamins A and D (like carrots, sweet potatoes, fatty fish, and egg yolks) may support lung health, though this study can’t prove it prevents lung disease. It’s one piece of evidence suggesting these vitamins matter for breathing, but you shouldn’t rely on supplements without talking to your doctor.
The Research Details
Researchers used information from a large national health survey called the National Health and Nutrition Examination Survey (NHANES), which tracks the health of thousands of Americans. They looked at data collected between 2007 and 2012 from 9,328 adults. Each person reported everything they ate in a single 24-hour period, which the researchers used to calculate how much vitamin A, D, E, and K they consumed.
To measure lung health, the researchers used two main tests. First, they used spirometry—a simple breathing test where you blow into a machine that measures how much air your lungs can hold and how fast you can push it out. Second, they measured something called fractional exhaled nitric oxide (FeNO), which is a marker of inflammation in the airways. Think of it like checking if your lungs are irritated or swollen.
The researchers then used statistical methods to see if people who ate more of these vitamins had better lung test results. They adjusted their analysis to account for other factors that affect lung health, like age, smoking, weight, and exercise habits, so they could isolate the effect of the vitamins themselves.
This approach is important because it looks at real people in their everyday lives rather than in a controlled lab setting. It helps researchers understand what patterns exist in the general population. However, because it’s a snapshot in time (cross-sectional), it can only show associations—not prove that vitamins cause better lung health.
This study has several strengths: it included a large, diverse group of Americans, used standardized lung function tests, and adjusted for many factors that could affect results. However, it has important limitations. It only measured diet once, so it doesn’t capture long-term eating patterns. It can’t prove cause-and-effect because people who eat more vitamins might also exercise more or have other healthy habits. The findings about vitamin thresholds (sweet spots for intake) are exploratory and need to be tested in future studies before we can trust them.
What the Results Show
The study found that vitamins A and D showed the strongest connections to lung health. For every additional microgram of vitamin D consumed per day, people’s forced vital capacity (a measure of total lung capacity) increased by about 3.72 milliliters. Vitamin A also showed a positive connection, though smaller—about 0.04 milliliters per microgram.
Interestingly, the researchers discovered that the relationship between these vitamins and one lung function measure (FEV1, which measures how much air you can exhale in one second) wasn’t simply “more is better.” Instead, they found an inverted U-shaped pattern, meaning there appeared to be an optimal amount. For vitamin D, the sweet spot seemed to be around 11.95 micrograms per day, and for vitamin A, around 958 micrograms per day. Below these amounts, more vitamin intake was associated with better lung function, but the researchers emphasized these threshold findings are preliminary and need confirmation.
Vitamins A and K were also connected to higher levels of FeNO (airway inflammation markers), with vitamin A increasing FeNO by about 1.1 parts per billion and vitamin K by 3.3 parts per billion per unit increase. This finding was somewhat unexpected and suggests the relationship between these vitamins and respiratory health is complex.
The study found that the connections between vitamins and lung function were stronger in people who were overweight. This suggests that body weight may play a role in how these vitamins affect lung health. Vitamin E and K showed weaker associations with lung function overall compared to vitamins A and D. The researchers noted that these secondary findings need further investigation to understand why overweight individuals showed different patterns.
Previous research has suggested that antioxidant vitamins (like A, D, and E) might protect lung tissue from damage. This study adds to that evidence by showing population-level associations in a large, diverse group. However, most previous studies were smaller or focused on specific populations like smokers or people with asthma. This research extends the findings to the general adult population, though it doesn’t definitively prove the vitamins prevent lung disease.
This study has several important limitations. First, it’s cross-sectional, meaning it’s a snapshot at one point in time—it can’t prove that eating more vitamins actually improves lung function, only that people who eat more vitamins tend to have better lung function. Second, diet was measured only once with a 24-hour recall, which may not represent someone’s typical eating patterns. Third, people who eat more vitamins might also have other healthy habits (exercise, not smoking) that actually explain the better lung function. Fourth, the threshold findings (the ‘sweet spot’ amounts) are exploratory and haven’t been confirmed in other studies. Finally, the study can’t account for all possible factors affecting lung health, though the researchers did adjust for many major ones.
The Bottom Line
Based on this research, eating foods naturally rich in vitamins A and D appears to support lung health. Good sources include: vitamin A (carrots, sweet potatoes, spinach, kale, liver) and vitamin D (fatty fish like salmon, egg yolks, fortified milk). However, this study doesn’t prove that supplements will help, and taking too much of fat-soluble vitamins can be harmful since they accumulate in your body. Confidence level: Low to Moderate. This is observational evidence suggesting an association, not proof of benefit. Talk to your doctor before taking vitamin supplements, especially if you have lung disease.
This research is most relevant to people interested in preventive health and nutrition. It may be particularly interesting to people with asthma, COPD, or other respiratory conditions, though they should consult their doctor before making dietary changes. People who are overweight may see stronger associations based on this study’s findings. This research is NOT a substitute for medical treatment of lung disease.
This study shows associations, not cause-and-effect, so we can’t say how quickly eating more of these vitamins would improve lung function. If you do increase your intake of vitamin A and D through food, any benefits would likely develop over months to years of consistent eating, not days or weeks.
Frequently Asked Questions
Does eating more vitamin A and D improve lung function?
This study shows an association between higher vitamin A and D intake and better lung function measurements in 9,328 adults, but it can’t prove cause-and-effect. People who eat more of these vitamins may also have other healthy habits. More research is needed to confirm whether increasing these vitamins actually improves breathing.
What foods should I eat to get more vitamin A and D for lung health?
Good vitamin A sources include carrots, sweet potatoes, spinach, and kale. Vitamin D comes from fatty fish (salmon, mackerel), egg yolks, and fortified milk. This study suggests these foods may support lung health, though it doesn’t prove they prevent disease. Eat a variety of these foods as part of a balanced diet.
Should I take vitamin A and D supplements for my lungs?
This study doesn’t test supplements, only food intake. Fat-soluble vitamins like A and D can accumulate to harmful levels in your body, so supplements aren’t automatically better than food. Talk to your doctor before taking supplements, especially if you have respiratory conditions or take other medications.
Why does the study show that more vitamin isn’t always better?
The researchers found inverted U-shaped relationships, meaning benefits increased up to a point (around 958 micrograms for vitamin A and 11.95 micrograms for vitamin D daily) then leveled off. This suggests optimal intake ranges exist, though these findings are preliminary and need confirmation in future studies.
Does this research apply to people with asthma or COPD?
This study included generally healthy adults from a national survey, not people with diagnosed lung disease. While the findings may be relevant, people with asthma, COPD, or other respiratory conditions should consult their doctor before making dietary changes or taking supplements based on this research.
Want to Apply This Research?
- Log daily intake of vitamin A and D sources (servings of carrots, sweet potatoes, salmon, egg yolks, fortified milk) and track monthly lung function using a peak flow meter if you have respiratory concerns. Correlate dietary patterns with any breathing improvements over 3-month periods.
- Add one vitamin A or D-rich food to your daily meals: a handful of spinach at lunch, a sweet potato at dinner, or an egg at breakfast. Track which foods you add and monitor how you feel energy-wise and breathing-wise over time.
- Create a simple food diary noting vitamin A and D sources consumed daily. If you have asthma or respiratory concerns, use a peak flow meter weekly and note any patterns between dietary intake and breathing measurements. Review trends monthly to see if increased vitamin intake correlates with improvements.
This study shows associations between vitamin intake and lung function measurements, not cause-and-effect relationships or proof of disease prevention. It cannot be used to diagnose, treat, or prevent any medical condition. People with respiratory diseases (asthma, COPD, etc.) should consult their healthcare provider before making dietary changes or taking supplements. Fat-soluble vitamins can accumulate to toxic levels, so supplements should only be taken under medical supervision. This research is observational and does not replace professional medical advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.