What to do for fighting the flu, I present vitamin D. There has been a great deal of research centered around vitamin D as of late, and for good reason – it has been discovered that this “vitamin” (which is actually a powerful steroid hormone precursor) is a vital nutrient necessary for many life processes not previously known. Vitamin D was discovered some time ago to play a powerful role in maintaining bone density and preventing osteoporosis and has recently been hypothesized to play a role in prevention of dementia. Other studies have found vitamin D to play a preventative role in “heart disease, hypertension, arthritis, chronic pain, depression, inflammatory bowel disease, obesity, premenstrual syndrome, muscular weakness, fibromyalgia, Crohn’s disease, multiple sclerosis, autoimmune illness, and cancer”. It even plays an important, although unknown role in weight loss.
That’s great and all, but what about the flu? Vitamin D has also been found to play a profound role in the immune system. It is an immune system modulator, preventing the over-expression of inflammatory cytokines. It also controls the expression of anti-microbial peptides, which may be where its importance against the flu comes into play. These anti-microbial peptides are present in the cells that line the respiratory tract, as well as in immune cells themselves. This gives a potent defense against flu and other respiratory invaders – and they’re stimulated by vitamin D. No vitamin D, no anti-microbials killing off flu viruses.
In fact, researchers speculate that lowered vitamin D rates from lack of sunlight in the winter may be what actually lead to a “flu season” in the first place. Past studies have found that ultraviolet radiation (from sun lamps or directly from sunlight) lowers the incidence of respiratory infections from viruses, as does supplementing with cod liver oil (which contains vitamin D). Paraphrasing nutritionist Byron Richards, while to blame all of the flu on vitamin D deficiency is a stretch as is suggesting that taking vitamin D is going to prevent everyone from getting the flu, “a lack of vitamin D is one factor that is easy to change and likely to contribute to a population of citizens less likely to rapidly spread the flu from one to another, in addition to helping individuals fight the flu or get a less severe case of the flu.”
So how does one up their vitamin D levels? The sun thankfully provides Vitamin D for free! While sunbathing is chastised due to the increased possibility of developing carcinogenic melanoma, few experts have looked at the repercussion to vitamin D levels of staying out of the sun and always applying sunscreen. Many experts consider this to be a drastic oversight and feel that at least some unhindered sun exposure is necessary daily.
Certain foods also have vitamin D, but not many that exist in the plant world. You can find natural occurring vitamin D in shiitake and button mushrooms, fish like mackerel, salmon, herring, sardines, catfish and tuna, or from eggs. As mentioned above, you can also get it from supplementing cod liver oil (I guess grandma was right about that one!). Note that foods that have been fortified with vitamin D, like milk, soy milk and cereals, are not the best choice. Fortified foods usually use vitamin D2 instead of vitamin D3 which is the kind made by your skin and is the more effective of the two. As well, fortified foods often do not provide enough vitamin D to compose a comprehensive health strategy.
But some doctors and nutritionists feel that the amount of vitamin D one gets from foods and the minimal sun exposure of the Western world is really not enough to maintain ideal levels for fighting off flu. In the past, when our ancestors worked outside during the day, the sun was an adequate source of vitamin D. Today, however, we’ve all moved indoors for most, if not all, of the day especially in cooler months. As a result, taking supplements of vitamin D may be a necessity.
Some may be surprised to find many nutritionists recommending between 1,000 to 5,000 IU per day, and some even going much higher. The Recommended Daily Intake (RDI) of vitamin D (200 to 600 IU per day), while possibly sufficient for preventing the bone diseases like rickets or osteoporosis, is too low to prevent many of the diseases now discovered to be affected by vitamin D levels. Indeed, many scientists are calling for an increase in the official RDI for vitamin D in order to help combat what is being called a “Vitamin D Deficiency Crisis“.
10,000 IU of vitamin D3 is what is provided by a single 20-30 minute session of sunlight, so many researchers feel this level of supplementation is perfectly safe.