By Dr. Mercola

The common cold is the most common infectious disease in the US and many other areas of the world.

Cold symptoms are triggered by hundreds of different viruses — not bacteria — and infection is typically spread by hand-to-hand contact between people, or by touching objects that harbor the pathogens.

Since colds are viral in nature, antibiotics are completely useless and should be avoided, unless your physician diagnoses a serious secondary bacterial infection. Using antibiotics when no bacterial pathogen is present simply contributes to the problem of antibiotic-resistant disease.

The key to preventing colds and recovering from them quickly is to maintain a strong immune system, which includes: optimizing your diet, avoiding sugar, optimizing your vitamin D level, getting enough sleep and exercise, managing your stress, and practicing good hand washing technique.

Just being exposed to a cold virus does not automatically mean you’ll catch a cold. If your immune system is operating at its peak, your body will be able to fend off the virus without ever getting sick, even if you’re exposed to it.

A number of foods, herbs, and supplements can be particularly helpful for promoting strong immune function^1,2,3 which is the focus of this article.

Boost Your Immune Function with Vitamin C-Rich Foods

Some health experts, such as Dr. Ronald Hunninghake, believe vitamin C is one of the nutrients you need whenever something ails you, be it the common cold or cancer. Vitamin C is best known for its benefits for infectious diseases though.

A perfect example of the healing power of this antioxidant vitamin is the dramatic case of Allan Smith, who contracted a serious case of swine flu, and was brought back from the brink of death using a combination of IV and oral vitamin C.

Research⁴ published in the Cochrane Database of Systematic Reviews in 2013 found that regular supplementation with vitamin C had a “modest but consistent effect in reducing the duration of common cold symptoms.”

Endurance athletes who took vitamin C supplements also halved their risk for the common cold.

Kiwi fruits are exceptionally high in vitamin C, along with vitamin E, folate, polyphenols, and carotenoids, and research⁵ published in the British Journal of Nutrition found that a kiwi-packed diet reduced the duration and severity of upper respiratory tract infections symptoms in older individuals.

Other foods high in vitamin C include: citrus fruits, red bell peppers, broccoli, Brussel sprouts, butternut squash, papaya, sweet potatoes, and tomatoes.

Vitamin D Deficiency Increases Your Risk of Catching a Cold

Vitamin D is another nutrient that tends to play a role in most diseases, especially infectious ones. It’s a potent antimicrobial agent, producing 200 to 300 different antimicrobial peptides in your body that kill bacteria, viruses, and fungi.

Suboptimal vitamin D levels will significantly impair your immune response and make you far more susceptible to contracting colds, influenza, and other respiratory infections.

The research is quite clear on this point: The higher your vitamin D level, the lower your risk of contracting colds, flu, and other respiratory tract infections.

In the largest and most nationally representative study⁶ of its kind, involving about 19,000 Americans, those with the lowest vitamin D levels reported having significantly more colds or cases of the flu.

At least five additional studies also show an inverse association between lower respiratory tract infections and vitamin D levels.

The best source for vitamin D is direct sun (UVB) exposure. If neither natural nor artificial sunlight is an option, then using an oral vitamin D3 supplement is recommended. Just remember you also need to increase your vitamin K2 when taking high doses of vitamin D3.

Based on the latest research from GrassrootsHealth, the average adult dose required to reach vitamin D levels of about 40 ng/ml is around 8,000 IUs of vitamin D3 per day. For children, many experts agree they need about 35 IUs of vitamin D per pound of body weight.

These are very general guidelines though. The only way to determine your optimal dose is to get your blood tested. Ideally, you’ll want to maintain a vitamin D level of 50 to 70 ng/ml year-round.

Chicken Soup Really Is a Valid Cold Remedy

Poor immune function tends to be rooted in an unbalanced mix of microorganisms in your digestive system, courtesy of an inappropriate and unbalanced diet that is too high in sugars and too low in healthful fats and beneficial bacteria. Homemade bone broth or “stock” is a valuable remedy, as it’s easily digestible and contains many valuable nutrients that help heal the lining of your intestines. This includes:

• Easily absorbable minerals, including magnesium, phosphorous, silicon, sulfur, and trace minerals
• Chondroitin sulfates, glucosamine, and other compounds extracted from the boiled down cartilage, which helps reduce joint pain and inflammation
• Amino acids such as glycine, proline, and arginine — all of which have anti-inflammatory effects.

Arginine, for example, has been found to be particularly beneficial for the treatment of sepsis⁷ (whole-body inflammation). Glycine also has calming effects, which may help you sleep better

Chicken soup made with homemade bone broth is excellent for speeding healing and recuperation from illness. You’ve undoubtedly heard the old adage that chicken soup will help cure a cold, and there’s scientific support⁸ for such a statement. A study⁹ published over a decade ago found that chicken soup indeed has medicinal qualities, significantly mitigating infection.

In addition to the anti-inflammatory benefits of bone broth, chicken contains a natural amino acid called cysteine, which can thin the mucus in your lungs and make it less sticky so you can expel it more easily. Keep in mind that processed, canned soups will not work as well as the homemade version made from slow-cooked bone broth.

If combating a cold, make the soup hot and spicy with plenty of pepper. The spices will trigger a sudden release of watery fluids in your mouth, throat, and lungs, which will help thin down the respiratory mucus so it’s easier to expel. Black peppercorns also contain high amounts of piperine, a compound with fever-reducing and pain-relieving properties.

Other Foods That Help Strengthen Immune Function

Maintaining a healthy diet and lifestyle year-round is the long-term solution to making it through cold and flu season unscathed. Detailed instructions that will help set you the right path can be found in my optimized nutrition and lifestyle plan, which is focused around real food. Importantly, if you feel yourself coming down with a cold or flu, AVOID all sugar, grains, artificial sweeteners, or processed foods.

Sugar is particularly damaging to your immune system — which needs to be ramped up, not suppressed, in order to combat an emerging infection. Other foods besides those mentioned above that can help strengthen your immune response include the following:

Fermented foods help “reseed” your gut with beneficial bacteria (examples include raw kefir, kimchee, miso, pickles, and sauerkraut).	Coconut oil contains lauric acid that your body converts into monolaurin, a monoglyceride with the ability to destroy lipid-coated viruses, including influenza, HIV, herpes, and measles, as well as gram-negative bacteria
Raw organic eggs from pastured chickens	Apple cider vinegar has anti-bacterial, anti-fungal, anti-viral, and anti-inflammatory properties. It may also help boost your immune function by raising alkalinity in your body.
Organic grass-fed beef is high in vitamins A and E, omega-3 fatty acids, beta-carotene, zinc, and CLA. CLA (conjugated linoleic acid, a fatty acid), an immune enhancer, is three to five times higher in grass-fed animals than grain-fed animals.	Garlic is a potent antibacterial, antiviral, and anti-fungal agent. Ideally consume it raw, and crush it just before eating. A previous article by PreventDisease.com10 gives instructions for a garlic soup that can help destroy most viruses and help you recover a little quicker.
Raw, grass-fed organic milk contains beneficial bacteria and fats that prime your immune system. It’s also a good source of vitamin A and zinc. Pasteurized dairy products are best avoided, as they may actually promote respiratory problems such a recurring colds, congestion, and bronchitis.11	Organic vegetables. Dark leafy greens such as kale, spinach, collard greens, and Swiss chard contain powerful antioxidants, flavonoids, carotenoids, and vitamin C — all of which help protect against infections. Ideally, opt for organic locally grown veggies that are in season, and consider eating a fair amount of them raw. Juicing is an excellent way to get more greens into your diet.

Immune-Boosting Herbs and Supplements

At first signs of a cold, you could also boost your immune function by taking a supplement or extract. The following are examples of immune-boosting herbs and supplements that may be helpful:

Zinc: Research on zinc has shown that when taken within one day of the first symptoms, zinc can cut down the time you have a cold by about 24 hours. Zinc was also found to greatly reduce the severity of symptoms. Suggested dosage: up to 50 mg/day. Zinc was not recommended for anyone with an underlying health condition, like lowered immune function, asthma, or chronic illness.	Curcumin, the pigment that gives turmeric its yellow-orange color, is known for its potent anti-inflammatory properties.
Olive leaf extract: Ancient Egyptians and Mediterranean cultures used it for a variety of health-promoting uses and it is widely known as a natural, non-toxic immune system builder.	Propolis: A bee resin and one of the most broad-spectrum antimicrobial compounds in the world; propolis is also the richest source of caffeic acid and apigenin, two very important compounds that aid in immune response.
Oregano Oil: The higher the carvacrol concentration, the more effective it is. Carvacrol is the most active antimicrobial agent in oregano oil.	Medicinal mushrooms, such as shiitake, reishi, and turkey tail have anti-inflammatory, antibacterial, and antiviral properties.
A tea made from a combination of elderflower, yarrow, boneset, linden, peppermint, and ginger; drink it hot and often for combating a cold or flu. It causes you to sweat, which is helpful for eradicating a virus from your system.	Echinacea is one of the most widely used herbal medications in Europe to combat colds and infections. One review of more than 700 studies found that using Echinacea can reduce your risk of catching cold by as much as 58 percent.
Elder flower extract: Rich in vitamin C and a wide range of valuable flavonoids, including anthocyanins and quercetin, elder flower has been traditionally used as a tonic to boost immunity. It is also widely known to promote lung and bronchial tract health.	Elderberry: In one study,12 elderberry syrup reduced the severity of flu symptoms and shortened their duration by about four days. Elderberry extract is also known for inducing sweating, and helps relieve congestion.

Another Trick to Beat a Cold: Hydrogen Peroxide

Generally speaking, unless you have a complication like pneumonia, medical care is not necessary for the common cold. Definitely avoid antibiotics, as they do not work on viral infections. Rest and attention to your diet — particularly the admonition to avoid sugar and the advice to cook up a batch of homemade chicken soup instead — will help you recover as quickly as possible. If you stick to these recommendations long-term, it will significantly reduce your chances of catching another cold in the future.

I don’t advise over-the-counter medications for the common cold, but one simple treatment you can try that is surprisingly effective against upper respiratory infections is hydrogen peroxide. Below is one of my first videos that is nearly 10 years old now that discusses using peroxide for colds.

While I was in practice, many patients at my Natural Health Center reported curing colds and flu within 12 to 14 hours simply by administering a few drops of 3 percent hydrogen peroxide (H2O2) into each ear. A bottle of hydrogen peroxide in 3 percent solution is available at any drug store for a couple of dollars or less. You will hear some bubbling, which is completely normal, and possibly feel a slight stinging sensation. Wait until the bubbling and stinging subside (usually 5 to 10 minutes), then drain onto a tissue and repeat with the other ear.

from:    http://articles.mercola.com/sites/articles/archive/2015/10/26/vitamin-c-foods-fight-common-cold.aspx