The common cold is a viral infection of the upper respiratory tract caused by some 200 different viruses, the most common of which are rhinoviruses. While there are not scientifically vetted cures for common colds, there are many proactive strategies both for preventing them and dampening the severity of their symptoms.
One effective strategy is maintaining adequate vitamin D levels. Emerging research, including both interventional and epidemiological studies, suggests that vitamin D plays a major role in regulating the immune system, including theorized direct anti-viral effects.1, 2 Research published in the British Journal of Nutrition shows vitamin D status to have a linear association with respiratory infections, though further research is needed to establish the underlying mechanisms.3
More than possibly preventing common colds, vitamin D may also accelerate your recovery once a rhinovirus infection takes hold. Rhinoviruses induce inflammatory responses in the airway epithelium by increasing pro-inflammatory cytokines.4 Research shows vitamin D can reduce this inflammation, though further research is again, required.5
While daily sun exposure is an ideal, it is not always feasible to maintain adequate vitamin D levels. Luckily, many Paleo foods are rich in vitamin D, particularly fatty fish. Mackerel, salmon, halibut, and herring are all potent sources of vitamin D. Just 3.5 oz. of mackerel has 360 IU vitamin D, or 90% of the USDA’s recommended daily value.6
With this recipe, you’ll also be getting a healthy dose of vitamin C from juiced limes. Vitamin C also boosts the immune system and may also protect against viral infections. Whether vitamin C reduces the incidence, duration, or severity of common colds has been a controversial, yet enduring hypothesis for over 70 years.7 Nevertheless, based on its low cost and low risks, many researchers recommend increased vitamin C consumption, whether from supplements or high-vitamin-C foods, for common cold prevention.8
With winter just around the corner, now is a great time to start increasing your consumption of vitamin D- and vitamin C-rich foods. Our delicious Mackerel Tartare will whet your appetite and amp up your immune system.
