from Chris Kesser
A nutrient-dense, toxin-free diet: avoid the foods that tend to weaken the immune system, such as sugar, unprepared grains, industrial seed oils and processed and refined foods.
Fermented cod liver oil/butter oil blend (FCLO/BO): if there’s only one superfood/supplement you take through the winter, this should be it. It’s rich with fat-soluble vitamins that regulate and support the immune system, and fatty acids like EPA and DHA that reduce inflammation. It also seems to have some kind of synergistic quality above and beyond the individual nutrients it contains that powerfully boosts immunity. I rarely get colds and flus when I’m taking my FCLO/BO. I prefer the Blue Ice brand available at Green Pasture. Dosage: 1 tsp/d or 2 caps per day.
Liver. Liver is nature’s multivitamin. It’s the most nutrient-dense food on the planet, as I explained here. I recommend eating 3 ounces a week if you’re taking FCLO/BO.
Bone broth. Grandma knew best! Homemade bone broth is rich with easily absorbable minerals such as magnesium, phosphorus, sulfur, and trace minerals difficult to obtain elsewhere. Check out the Weston A. Price article “Broth is Beautiful” for recipes and more information.
Fermented foods and/or probiotics: 70-80% of our immune system is in our gut. If you have intestinal dysbiosis or poor gut flora, you’ll be more susceptible to viral and bacterial infections (and colds and flus).
Vitamin C: I don’t supplement with vitamin C at all times during the year, but when cold and flu season rolls around, I’ll often take 1 g/d as a precaution.
Vitamin D. Vitamin D plays a powerful immunoregulatory role. For most people, the FCLO/BO blend should be enough to maintain adequate vitamin D levels. However, some people require higher doses of vitamin D to keep their 25D levels in the desired range of 35-60 ng/mL. This is especially true of those with obesity or inflammation, because these conditions impair the conversion of sunlight to vitamin D. Dosage: 2,000 -- 4,000 IU/d depending on beginning level and amount of FCLO/BO you’re taking.
Jade Windscreen Formula. Jade Windscreen (or Yu Ping Feng San in Pinyin Chinese) is an immune system tonic made up of botanicals that enhance the immune system and have anti-viral and anti-microbial properties. The traditional formula contains Astragalus, Actractylodes and Ledebouriella, but modern preparations also add cinnamon, siler root, Chinese yam rhizome, and white peony root. You can often buy Jade Windscreen at a health food store or natural pharmacy. You can also buy it online. I like the Kan Herbs tincture. Dosage: 10-20 drops 2-3x/daily (check with your medical provider if you are pregnant or nursing or have an autoimmune condition)
Sleep and rest. Getting adequate sleep and rest is perhaps the most important thing you can do to optimize your immune function. Just a few nights of not sleeping well can elevate inflammatory markers and reduce the protective capability of your immune system. That’s why it’s a good idea to go to bed earlier, sleep longer and rest more in the winter season.