7 Healthy Foods That Are High in Vitamin D
However, up to 50% of the world's population may not get enough sun, and 40% of U.S. residents are deficient in vitamin D.
This is partly because people spend more time indoors, wear sunblock outside, and eat a Western diet low in good sources of this vitamin.
If you don't get enough sunlight, your intake should likely be closer to 1,000 IU (25 mcg) per day.
Here are 7 healthy foods that are high in vitamin D.
Salmon is a popular fatty fish and great source of vitamin D.
Whether the salmon is wild or farmed can make a big difference.
On average, wild-caught salmon packs 988 IU of vitamin D per 3.5-ounce (100-gram) serving, or 124% of the DV. Some studies have found even higher levels in wild salmon — up to 1,300 IU per serving.
However, farmed salmon contains only 25% of that amount. Still, one serving of farmed salmon provides about 250 IU of vitamin D, or 32% of the DV.
Wild salmon contains about 988 IU of vitamin D per serving, while farmed salmon contains 250 IU, on average. That's 124% and 32% of the DV, respectively.
2. Herring and Sardines
Herring is a fish eaten around the world. It can be served raw, canned, smoked, or pickled.
This small fish is also one of the best sources of vitamin D.
If fresh fish isn't your thing, pickled herring is also a good source of vitamin D, providing 112 IU per 3.5-ounce (100-gram) serving, or 14% of the DV.
However, pickled herring also contains a high amount of sodium, which some people consume too much of.
Canned sardines are a good source of vitamin D as well — one can (3.8 ounces) contains 177 IU, or 22% of the DV.
Other types of fatty fish are also good vitamin D sources. Halibut and mackerel provide 384 IU and 360 IU per half a fillet, respectively.
Herring contains 216 IU of vitamin D per 3.5-ounce (100-gram) serving. Pickled herring, sardines, and other fatty fish, such as halibut and mackerel, are also good sources.
3. Cod Liver Oil
Cod liver oil is a popular supplement. If you don't like fish, taking cod liver oil can be key to obtaining certain nutrients that are unavailable in other sources.
It's an excellent source of vitamin D — at about 448 IU per teaspoon (4.9 ml), it clocks in at a massive 56% of the DV. It has been used for many years to prevent and treat deficiency in children.
Cod liver oil is likewise a fantastic source of vitamin A, with 150% of the DV in just one teaspoon (4.9 ml). However, vitamin A can be toxic in high amounts.
Therefore, be cautious with cod liver oil, making sure to not take too much.
In addition, cod liver oil is high in omega-3 fatty acids, which many people are deficient in.
Cod liver oil contains 448 IU of vitamin D per teaspoon (4.9 ml), or 56% of the DV. It is also high in other nutrients, such as vitamin A and omega-3 fatty acids.
4. Canned Tuna
Many people enjoy canned tuna because of its flavor and easy storage methods.
It's also usually cheaper than buying fresh fish.
Canned light tuna packs up to 268 IU of vitamin D in a 3.5-ounce (100-gram) serving, which is 34% of the DV.
It's also a good source of niacin and vitamin K.
Unfortunately, canned tuna contains methylmercury, a toxin found in many types of fish. If it builds up in your body, it can cause serious health problems.
However, some types of fish pose less risk than others. For instance, light tuna is typically a better choice than white tuna — it's considered safe to eat up to 6 ounces (170 grams) per week.
Canned tuna contains 268 IU of vitamin D per serving. Choose light tuna and eat 6 ounces (170 grams) or less per week to prevent methylmercury buildup.
5. Egg Yolks
People who don't eat fish should know that seafood is not the only source of vitamin D. Whole eggs are another good source, as well as a wonderfully nutritious food.
While most of the protein in an egg is found in the white, the fat, vitamins, and minerals are found mostly in the yolk.
One typical egg yolk contains 37 IU of vitamin D, or 5% of the DV.
Vitamin D levels in egg yolk depend on sun exposure and the vitamin D content of chicken feed. When given the same feed, pasture-raised chickens that roam outside in the sunlight produce eggs with levels 3–4 times higher.
Additionally, eggs from chickens given vitamin-D-enriched feed may have up to 6,000 IU of vitamin D per yolk. That's a whopping 7 times the DV.
Choosing eggs either from chickens raised outside or marketed as high in vitamin D can be a great way to meet your daily requirements.
Eggs from commercially raised hens contain only about 37 IU of vitamin D per yolk. However, eggs from hens raised outside or fed vitamin-D-enriched feed contain much higher levels.
Excluding fortified foods, mushrooms are the only good plant source of vitamin D.
Like humans, mushrooms can synthesize this vitamin when exposed to UV light.
However, mushrooms produce vitamin D2, whereas animals produce vitamin D3.
Though vitamin D2 helps raise blood levels of vitamin D, it may not be as effective as vitamin D3.
Nonetheless, wild mushrooms are excellent sources of vitamin D2. In fact, some varieties pack up to 2,300 IU per 3.5-ounce (100-gram) serving — nearly three times the DV.
On the other hand, commercially grown mushrooms are often grown in the dark and contain very little D2.
Mushrooms can synthesize vitamin D2 when exposed to UV light. Only wild mushrooms or mushrooms treated with UV light are good sources of vitamin D.
7. Fortified Foods
Natural sources of vitamin D are limited, especially if you're vegetarian or don't like fish.
Fortunately, some food products that don't naturally contain vitamin D are fortified with this nutrient.
Cow's milk, the most commonly consumed type of milk, is naturally a good source of many nutrients, including calcium, phosphorous, and riboflavin.
In several countries, cow's milk is fortified with vitamin D. It usually contains about 115–130 IU per cup (237 ml), or about 15–22% of the DV.
Because vitamin D is found almost exclusively in animal products, vegetarians and vegans are at a particularly high risk of not getting enough.
For this reason, plant-based milk substitutes like soy milk are often fortified with this nutrient and other vitamins and minerals usually found in cow's milk.
One cup (237 ml) typically contains 107–117 IU of vitamin D, or 13–15% of the DV.
Around 75% of people worldwide are lactose intolerant, and another 2–3% have a milk allergy.
For this reason, some countries fortify orange juice with vitamin D and other nutrients, such as calcium.
Cereal and Oatmeal
Certain cereals and instant oatmeal are also fortified with vitamin D.
Though fortified cereals and oatmeal provide less vitamin D than many natural sources, they can still be a good way to boost your intake.
Foods such as cow's milk, soy milk, orange juice, cereals, and oatmeal are sometimes fortified with vitamin D. These contain 54–136 IU per serving.
Vitamin D and Calcium
Getting enough of both vitamin D and calcium is crucial to maintaining bone health and protecting against disorders like osteoporosis, a condition that is characterized by weak, brittle bones.
Children and adults aged 1–70 need approximately 600 IU of vitamin D per day, and it can come from a combination of food sources and sunlight. Meanwhile, adults over 70 should aim for at least 800 IU (20 mcg) of vitamin D per day.
The daily value (DV), a rating system used on the labels of packaged food, is 800 IU per day.
Calcium needs also vary by age. Children aged 1–8 require about 2,500 mg of calcium daily, and those ages 9–18 need approximately 3,000 mg daily.
Your body needs vitamin D to absorb calcium. This makes getting enough of both vitamin D and calcium crucial to maintaining bone health and preventing osteoporosis.
The Bottom Line
Spending time in the sun is a good way to get your daily dose of vitamin D. However, sufficient sun exposure is difficult for many people to achieve.
Getting enough from your diet alone may be difficult, but not impossible.
The foods listed in this article are some of the top sources of vitamin D available.
Eating plenty of these vitamin-D-rich foods is a great way to make sure you get enough of this important nutrient.
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By Ana Maldonado-Contreras
- Your gut is home to trillions of bacteria that are vital for keeping you healthy.
- Some of these microbes help to regulate the immune system.
- New research, which has not yet been peer-reviewed, shows the presence of certain bacteria in the gut may reveal which people are more vulnerable to a more severe case of COVID-19.
You may not know it, but you have an army of microbes living inside of you that are essential for fighting off threats, including the virus that causes COVID-19.
How Do Resident Bacteria Keep You Healthy?<p>Our immune defense is part of a complex biological response against harmful pathogens, such as viruses or bacteria. However, because our bodies are inhabited by trillions of mostly beneficial bacteria, virus and fungi, activation of our immune response is tightly regulated to distinguish between harmful and helpful microbes.</p><p>Our bacteria are spectacular companions diligently helping prime our immune system defenses to combat infections. A seminal study found that mice treated with antibiotics that eliminate bacteria in the gut exhibited an impaired immune response. These animals had low counts of virus-fighting white blood cells, weak antibody responses and poor production of a protein that is vital for <a href="https://doi.org/10.1073/pnas.1019378108" target="_blank">combating viral infection and modulating the immune response</a>.</p><p><a href="https://doi.org/10.1371/journal.pone.0184976" target="_blank" rel="noopener noreferrer">In another study</a>, mice were fed <em>Lactobacillus</em> bacteria, commonly used as probiotic in fermented food. These microbes reduced the severity of influenza infection. The <em>Lactobacillus</em>-treated mice did not lose weight and had only mild lung damage compared with untreated mice. Similarly, others have found that treatment of mice with <em>Lactobacillus</em> protects against different <a href="https://doi.org/10.1038/srep04638" target="_blank" rel="noopener noreferrer">subtypes of</a> <a href="https://doi.org/10.1038/s41598-017-17487-8" target="_blank" rel="noopener noreferrer">influenza</a> <a href="https://doi.org/10.1371/journal.ppat.1008072" target="_blank" rel="noopener noreferrer">virus</a> and human respiratory syncytial virus – the <a href="https://doi.org/10.1038/s41598-019-39602-7" target="_blank" rel="noopener noreferrer">major cause of viral bronchiolitis and pneumonia in children</a>.</p>
Chronic Disease and Microbes<p>Patients with chronic illnesses including Type 2 diabetes, obesity and cardiovascular disease exhibit a hyperactive immune system that fails to recognize a harmless stimulus and is linked to an altered gut microbiome.</p><p>In these chronic diseases, the gut microbiome lacks bacteria that activate <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">immune cells</a> that block the response against harmless bacteria in our guts. Such alteration of the gut microbiome is also observed in <a href="https://doi.org/10.1073/pnas.1002601107" target="_blank" rel="noopener noreferrer">babies delivered by cesarean section</a>, individuals consuming a poor <a href="https://doi.org/10.1038/nature12820" target="_blank" rel="noopener noreferrer">diet</a> and the <a href="https://doi.org/10.1038/nature11053" target="_blank" rel="noopener noreferrer">elderly</a>.</p><p>In the U.S., 117 million individuals – about half the adult population – <a href="https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/" target="_blank" rel="noopener noreferrer">suffer from Type 2 diabetes, obesity, cardiovascular disease or a combination of them</a>. That suggests that half of American adults carry a faulty microbiome army.</p><p>Research in my laboratory focuses on identifying gut bacteria that are critical for creating a balanced immune system, which fights life-threatening bacterial and viral infections, while tolerating the beneficial bacteria in and on us.</p><p>Given that diet affects the diversity of bacteria in the gut, <a href="https://www.umassmed.edu/nutrition/melody-trial-info/" target="_blank" rel="noopener noreferrer">my lab studies show how diet can be used</a> as a therapy for chronic diseases. Using different foods, people can shift their gut microbiome to one that boosts a healthy immune response.</p><p>A fraction of patients infected with SARS-CoV-2, the virus that causes COVID-19 disease, develop severe complications that require hospitalization in intensive care units. What do many of those patients have in common? <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e2.htm" target="_blank" rel="noopener noreferrer">Old age</a> and chronic diet-related diseases like obesity, Type 2 diabetes and cardiovascular disease.</p><p><a href="http://doi.org/10.1016/j.jada.2008.12.019" target="_blank" rel="noopener noreferrer">Black and Latinx people are disproportionately affected by obesity, Type 2 diabetes and cardiovascular disease</a>, all of which are linked to poor nutrition. Thus, it is not a coincidence that <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6933e1.htm" target="_blank" rel="noopener noreferrer">these groups have suffered more deaths from COVID-19</a> compared with whites. This is the case not only in the U.S. but also <a href="https://www.washingtonpost.com/world/europe/blacks-in-britain-are-four-times-as-likely-to-die-of-coronavirus-as-whites-data-show/2020/05/07/2dc76710-9067-11ea-9322-a29e75effc93_story.html" target="_blank" rel="noopener noreferrer">in Britain</a>.</p>
Discovering Microbes That Predict COVID-19 Severity<p>The COVID-19 pandemic has inspired me to shift my research and explore the role of the gut microbiome in the overly aggressive immune response against SARS-CoV-2 infection.</p><p>My colleagues and I have hypothesized that critically ill SARS-CoV-2 patients with conditions like obesity, Type 2 diabetes and cardiovascular disease exhibit an altered gut microbiome that aggravates <a href="https://theconversation.com/exercise-may-help-reduce-risk-of-deadly-covid-19-complication-ards-136922" target="_blank" rel="noopener noreferrer">acute respiratory distress syndrome</a>.</p><p>Acute respiratory distress syndrome, a life-threatening lung injury, in SARS-CoV-2 patients is thought to develop from a <a href="http://doi.org/10.1016/j.cytogfr.2020.05.003" target="_blank" rel="noopener noreferrer">fatal overreaction of the immune response</a> called a <a href="https://theconversation.com/blocking-the-deadly-cytokine-storm-is-a-vital-weapon-for-treating-covid-19-137690" target="_blank" rel="noopener noreferrer">cytokine storm</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">that causes an uncontrolled flood</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">of immune cells into the lungs</a>. In these patients, their own uncontrolled inflammatory immune response, rather than the virus itself, causes the <a href="http://doi.org/10.1007/s00134-020-05991-x" target="_blank" rel="noopener noreferrer">severe lung injury and multiorgan failures</a> that lead to death.</p><p>Several studies <a href="https://doi.org/10.1016/j.trsl.2020.08.004" target="_blank" rel="noopener noreferrer">described in one recent review</a> have identified an altered gut microbiome in patients with COVID-19. However, identification of specific bacteria within the microbiome that could predict COVID-19 severity is lacking.</p><p>To address this question, my colleagues and I recruited COVID-19 hospitalized patients with severe and moderate symptoms. We collected stool and saliva samples to determine whether bacteria within the gut and oral microbiome could predict COVID-19 severity. The identification of microbiome markers that can predict the clinical outcomes of COVID-19 disease is key to help prioritize patients needing urgent treatment.</p><p><a href="https://doi.org/10.1101/2021.01.05.20249061" target="_blank" rel="noopener noreferrer">We demonstrated</a>, in a paper which has not yet been peer reviewed, that the composition of the gut microbiome is the strongest predictor of COVID-19 severity compared to patient's clinical characteristics commonly used to do so. Specifically, we identified that the presence of a bacterium in the stool – called <em>Enterococcus faecalis</em>– was a robust predictor of COVID-19 severity. Not surprisingly, <em>Enterococcus faecalis</em> has been associated with <a href="https://doi.org/10.1053/j.gastro.2011.05.035" target="_blank" rel="noopener noreferrer">chronic</a> <a href="https://doi.org/10.1016/S0002-9440(10)61172-8" target="_blank" rel="noopener noreferrer">inflammation</a>.</p><p><em>Enterococcus faecalis</em> collected from feces can be grown outside of the body in clinical laboratories. Thus, an <em>E. faecalis</em> test might be a cost-effective, rapid and relatively easy way to identify patients who are likely to require more supportive care and therapeutic interventions to improve their chances of survival.</p><p>But it is not yet clear from our research what is the contribution of the altered microbiome in the immune response to SARS-CoV-2 infection. A recent study has shown that <a href="https://doi.org/10.1101/2020.12.11.416180" target="_blank" rel="noopener noreferrer">SARS-CoV-2 infection triggers an imbalance in immune cells</a> called <a href="https://doi.org/10.1111/imr.12170" target="_blank" rel="noopener noreferrer">T regulatory cells that are critical to immune balance</a>.</p><p>Bacteria from the gut microbiome are responsible for the <a href="https://doi.org/10.7554/eLife.30916.001" target="_blank" rel="noopener noreferrer">proper activation</a> <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">of those T-regulatory</a> <a href="https://doi.org/10.1038/nri.2016.36" target="_blank" rel="noopener noreferrer">cells</a>. Thus, researchers like me need to take repeated patient stool, saliva and blood samples over a longer time frame to learn how the altered microbiome observed in COVID-19 patients can modulate COVID-19 disease severity, perhaps by altering the development of the T-regulatory cells.</p><p>As a Latina scientist investigating interactions between diet, microbiome and immunity, I must stress the importance of better policies to improve access to healthy foods, which lead to a healthier microbiome. It is also important to design culturally sensitive dietary interventions for Black and Latinx communities. While a good-quality diet might not prevent SARS-CoV-2 infection, it can treat the underlying conditions related to its severity.</p><p><em><a href="https://theconversation.com/profiles/ana-maldonado-contreras-1152969" target="_blank">Ana Maldonado-Contreras</a> is an assistant professor of Microbiology and Physiological Systems at the University of Massachusetts Medical School.</em></p><p><em>Disclosure statement: Ana Maldonado-Contreras receives funding from The Helmsley Charitable Trust and her work has been supported by the American Gastroenterological Association. She received The Charles A. King Trust Postdoctoral Research Fellowship. She is also member of the Diversity Committee of the American Gastroenterological Association.</em></p><p><em style="">Reposted with permission from <a href="https://theconversation.com/a-healthy-microbiome-builds-a-strong-immune-system-that-could-help-defeat-covid-19-145668" target="_blank" rel="noopener noreferrer" style="">The Conversation</a>. </em></p>
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