There’s little evidence yet, except maybe in people who are deficient in vitamins and minerals
Consumers have long turned to vitamins and herbs to try to protect themselves from disease. This pandemic is no different — especially with headlines that scream “This supplement could save you from coronavirus.”
It also helps to have celebrity enthusiasts. When President Donald Trump was diagnosed with COVID-19, his pill arsenal included Vitamin D and zinc. And in an Instagram chat with actress Jennifer Garner in September, infectious diseases expert Anthony Fauci touted vitamins C and D as ways that might generally boost the immune system. “If you’re deficient in vitamin D,” he noted, “that does have an impact on your susceptibility to infection. I would not mind recommending, and I do it myself, taking vitamin D supplements.”
What it is: Called “the sunshine vitamin” because the body makes it naturally in the presence of ultraviolet light, Vitamin D is one of the most heavily studied supplements (SN: 1/27/19). Certain foods, including fish and fortified milk products, are also high in the vitamin.
Why it might help: Vitamin D is a hormone building block that helps strengthen the immune system.
How it works for other infections: In 2017, the British Medical Journal published a meta-analysis that suggested a daily vitamin D supplement might help prevent respiratory infections, particularly in people who are deficient in the vitamin.
But one key word here is deficient. That risk is highest during dark winters at high latitudes and among people with more color in their skin (melanin, a pigment that’s higher in darker skin, inhibits the production of vitamin D).
“If you have enough vitamin D in your body, the evidence doesn’t stack up to say that giving you more will make a real difference,” says Susan Lanham-New, head of the nutritional sciences department at the University of Surrey in England.
And taking too much can create new health problems, stressing certain internal organs and leading to a dangerously high calcium buildup in the blood. The recommended daily allowance for adults is 600 to 800 international units per day, and the upper limit is considered to be 4,000 IU per day.
What we know about Vitamin D and COVID-19: Few studies have looked directly at whether vitamin D makes a difference in COVID-19.
In May, in the BMJ Nutrition, Prevention & Health, Lanham-New and her colleagues published a summary of existing evidence and concluded that there’s only enough to recommend vitamin D to help with COVID-19 prevention for people who are deficient. That paper made inferences from how vitamin D works against other respiratory tract infections and immune health.
More than a dozen studies are now testing vitamin D directly for prevention and treatment, including a large one led by JoAnn Manson, a leading expert on vitamin D and an epidemiologist and preventive medicine physician at Harvard Medical School and Brigham & Women’s Hospital in Boston. That study will analyze if vitamin D can affect the course of a COVID-19 infection. The trial aims to recruit 2,700 people across the United States with newly diagnosed infections, along with their close household contacts.
The goal is to determine whether newly diagnosed people given high doses of vitamin D — 3,200 IU per day — are less likely than people who get a placebo to experience severe symptoms and need hospitalization. “The biological plausibility for a benefit in COVID is compelling,” she says, given the nutrient’s theoretical ability to impede the severe inflammatory reaction that can follow coronavirus infection. “However the evidence is not conclusive at this time.”
What it is: Zinc, a mineral found in cells all over the body, is found naturally in certain meats, beans and oysters.
Why it might help: It plays several supportive roles in the immune system, which is why zinc lozenges are always hot sellers in cold and flu season. Zinc also helps with cell division and growth.
How it works for other infections: Studies of using zinc for colds — which are frequently caused by coronaviruses — suggest that using a supplement right after symptoms start might make them go away quicker. That said, a clinical trial from researchers in Finland and the United Kingdom, published in January in BMJ Open did not find any value for zinc lozenges for the treatment of colds. Some researchers have theorized that inconsistences in data for colds may be explained by varying amounts of zinc released in different lozenges.
What we know about zinc and COVID-19: The mineral is promising enough that it was added to some early studies of hydroxychloroquine, a drug tested early in the pandemic. (Studies have since shown that hydroxychloroquine can’t prevent or treat COVID-19 (SN: 8/2/20).)
In July, researchers from Aachen University in Germany wrote in Frontiers of Immunology that current evidence “strongly suggests great benefits of zinc supplementation” based on looking at similar infections including SARS, another disease caused by a coronavirus. For example, studies suggest that giving zinc reduces the risk for death from a pneumonia infection. The researchers cite evidence that zinc might help prevent the virus from entering the body, and help slow the virus’s replication when it does.
Another review — also based on indirect evidence — published August 1 in Advances in Integrative Medicine also concluded that zinc might be helpful in people who are deficient.
In September, researchers from Hospital Del Mar in Barcelona reported that among 249 patients studied, those who survived COVID had higher zinc levels in their plasma (an average of 63.1 mcg/dl) than those who died (43mcg/dl).
What it is: Also called L-ascorbic acid, vitamin C has a long list of roles in the body. It’s found naturally in fruits and vegetables, especially citrus, peppers and tomatoes.
Why it might help: It’s a potent antioxidant that’s important for a healthy immune system and preventing inflammation.
How it works for other infections: Thomas cautions that the data on vitamin C are often contradictory. One review from Chinese researchers, published in February in the Journal of Medical Virology, looked at what is already known about vitamin C and other supplements that might have a role in COVID-19 treatment. Among other encouraging signs, human studies find a lower incidence of pneumonia among people taking vitamin C, “suggesting that vitamin C might prevent the susceptibility to lower respiratory tract infections under certain conditions.”
But for preventing colds, a 2013 Cochrane review of 29 studies didn’t support the idea that vitamin C supplements could help in the general population. However, the authors wrote, given that vitamin C is cheap and safe, “it may be worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial.”
What we know about Vitamin C and COVID-19: About a dozen studies are under way or planned to examine whether vitamin C added to coronavirus treatment helps with symptoms or survival, including Thomas’ study at the Cleveland Clinic.
In a review published online in July in Nutrition, researchers from KU Leuven in Belgium concluded that the vitamin may help prevent infection and tamp down the dangerous inflammatory reaction that can cause severe symptoms, based on what is known about how the nutrient works in the body.
Melissa Badowski, a pharmacist who specializes in viral infections at the University of Illinois at Chicago College of Pharmacy, and colleague Sarah Michienzi published an extensive look at all supplements that might be useful in the coronavirus epidemic. There’s still not enough evidence to know whether they are helpful, the pair concluded in July in Drugs in Context. “It’s not really clear if it’s going to benefit patients,” Badowski says.
And while supplements are generally safe, she adds that nothing is risk free. The best way to avoid infection, she says, is still to follow the advice of epidemiologists and public health experts: “Wash your hands, wear a mask, stay six feet apart.”
A.R. Martineau et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. British Medical Journal. Published online February 15, 2017. doi: 10.1136/bmj.i6583.
S.A. Lanham-New et al. Vitamin D and SARS-CoV-2 virus/COVID-19 disease. BMJ Nutrition, Prevention & Health. Published online May 13, 2020. doi: 10.1136/bmjnph-2020-000089.
M. Singh and R.R. Das. Zinc for the common cold. Cochrane Database Systematic Reviews. Published online April 30, 2015. doi: 10.1002/14651858.CD001364.pub5.
H. Hemilä et al. Zinc acetate lozenges for the treatment of the common cold: a randomised controlled trial. BMJ Open. Vol. 10, January 2020. Doi: 10.1136/bmjopen-2019-031662.
I. Wessels, B. Rolles and L. Rink. The potential impact of zinc supplementation on COVID-19 pathogenesis. Frontiers in Immunology. Published online July 10, 2020. doi: 10.3389/fimmu.2020.01712.
R. Güerri-Fernández et al. Lower baseline zinc levels are associated with poorer outcome in COVID-19. ESCMID Conference on Coronavirus Disease. September 23, 2020.
S. Arentz et al. Zinc for the prevention and treatment of SARS-CoV-2 and other acute viral respiratory infections: a rapid review. Advances in Integrative Medicine. Published online August 1, 2020. doi: 10.1016/j.aimed.2020.07.009
S.R. Bauer et al. What is the role of supplementation with ascorbic acid, zinc, vitamin D, or N-acetylcysteine for prevention or treatment of COVID-19? Cleveland Clinic Journal of Medicine. June 2020. Doi: 10.3949/ccjm.87a.ccc046.
L. Zhang and Y. Liu. Potential interventions for novel coronavirus in China: A systematic review. Journal of Medical Virology. Published online February 13, 2020. doi: 10.1002/jmv.25707.
H. Hemilä and E. Chalker. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews. Published online January 13, 2013. doi: 10.1002/14651858.CD000980.pub4.
S. Michienzi and M.E. Badowski. Can vitamins and/or supplements provide hope against coronavirus? Drugs in Context. Published online June 22, 2020. Doi: 10.7573/dic.2020-5-7.
A new study has suggested that people who exercise in the morning between 8:00 a.m. and 10:00 a.m. may be less likely to develop cancers than those who exercise later in the day.
New research has suggested that people who exercise in the early morning may have a reduced risk of developing cancer than those who exercise later in the day.
The research, appearing in the International Journal of Cancer, may help inform future research into the timing of exercise as a potential way of reducing cancer risk.
Research has shown that doing recreational exercise can reduce a person’s risk of developing many different cancers.
This information is important because of the high numbers of people who develop cancer and the significant number who die of the disease. For example, in the United States, scientists estimate that by the end of 2020, 1,806,590 people will receive a diagnosis of cancer, while 606,520 people will die from the disease.
Given the large numbers of people who develop cancer, even a change as small as changing the time a person exercises could make a significant contribution to reducing the impact of cancer across a whole population.
As of 2018, 46.7% of adults in the U.S. did not meet the minimum aerobic physical activity guidelines. Increasing physical activity and optimizing when it is most effective might be a possible way of reducing the prevalence of cancer in society.
There is also evidence that a person’s circadian rhythm may have links to their chance of developing cancer. The phrase circadian rhythm refers to the biological processes that affect a person’s sleep-wake cycle.
The International Agency for Research on Cancer have classified the level of evidence linking night shift work that disrupts a person’s circadian rhythm as “probably” carcinogenic to humans.
In particular, researchers have linked night shift work to an increased risk of breast cancer. The evidence for prostate cancer remains unclear.
Scientists have shown that exercise also has a relationship with a person’s circadian rhythm. According to 2019 research, exercising during the day may help improve a person’s circadian rhythm and lessen the adverse effects of disrupted sleep patterns.
Given that exercise can potentially reduce the risks of cancer and improve circadian rhythms and disrupted circadian rhythms can increase cancer risk, the authors of the new research hypothesized that the timing of physical activity might affect cancer risk.
To test this hypothesis, the researchers behind the present study analyzed the data from 2,795 participants. The participants were a subset of the Spanish multi case-control study (MCC-Spain), which set out to understand factors causing common cancers in Spain and how to prevent them.
From 2008–2013, researchers interviewed the participants to find out their lifetime recreational and household physical activity. An average of 3 years later, researchers assessed the timing of when people exercised.
The researchers looked in particular at the 781 women who had breast cancer and also responded to the questionnaire about their physical activity and 504 men who had prostate cancer and provided data about the timing of their exercise.
The researchers chose the controls in the MCC-Spain study randomly from general practice records. The researchers matched them to people in the study with cancer who were of the same sex and similar age. The controls in this study also responded to the follow-up questions about physical activity and its timings.
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The researchers found that physical activity between 8:00 a.m. and 10:00 a.m. had the strongest potential beneficial effect at reducing breast and prostate cancer.
About 7% of the people with breast cancer and 9% of people in the control group undertook most of their exercise in the early morning. About 12.7% of people with prostate cancer and 14% of the control group did early morning exercise.
The researchers developed a model that showed that the odds of developing breast cancer were potentially 25% lower due to exercising in the morning compared with not exercising.
However, the statistical confidence of this estimate ranges from a 52% reduction to a 15% increase in risk.
The results show a similar picture for prostate cancer. The model predicted that those who exercised in the early morning had a 27% reduced chance of having prostate cancer than non-exercisers. However, the range went from a 56% reduction to a 20% increase.
People who exercised in the evening, between 7:00 p.m. and 11:00 p.m., had a 25% reduced risk for developing prostate cancer. However, as with the early morning findings, the evidence is not statistically significant.
The researchers suggest that any beneficial effects of early exercise for breast cancer risk may have links to estrogen. High estrogen levels have associations with an increased risk of breast cancer, and exercise can lower estrogen levels. Further, estrogen production is most active at around 7:00 a.m.
Melatonin may also be a factor. Researchers have shown that melatonin may protect against cancer risk and that exercise later in the day or at night can delay melatonin production.
As the researchers note, the study has limitations, and they could not detect the small effect that the timing of exercise might have with certainty.
However, the small size of the effect does not mean it is unimportant. Cancer is a prolific disease, and any small effects, when amplified across a population, can be important.
Other study problems include not recording all the information for all participants and not considering some confounding variables, such as diet and sleep patterns.
However, these were minor issues relative to the sample size, and the differences between the cases and controls in this study were small.
Nonetheless, the study clarifies the value of exploring the association between exercise time and cancer risk further.
For Dr. Manolis Kogevinas, Scientific Director of the Severo Ochoa Distinction at ISGlobal in Barcelona and the coordinator of the study, “[t]hese results, if confirmed, may improve current physical activity recommendations for cancer prevention. [What is] clear is that everyone can reduce their cancer risk simply by being moderately physically active for at least 150 minutes each week.”