This article was updated on July 6, 2019, by the original author.
Our relationship with food will influence our health outcomes and quality of life. What we choose to eat day to day, week to week and year to year, can create either radiant good health and well-being or accelerate the aging process and induce preventable diseases.
As discussed in part 1, cooking foods denatures and/or reduces the nutrients contained within. If you haven’t read part 1 do so now, before continuing. And heat doesn’t just damage vitamins. While the majority of minerals are a bit more resistant to heat than their vitamin counterparts, they can also be destroyed by the cooking process. Fortunately, the following immunity boosting mineral antioxidants are more resistant to heat:
According to The American Society for Nutritional Sciences, “Selenium is essential for the efficient and effective operation of many aspects of the immune system in both animals and humans.”1 And selenium is a mineral that many people, around the globe, are not getting enough of. Some experimental studies suggest that low selenium intake may be contributing to “reduced immune function, increased cancer incidence, and increased susceptibility to viral disease.”2 And this isn’t just happening in poorer nations suffering from drought and food shortages. Selenium deficiency has become a first world problem.“Selenium is essential for the efficient and effective operation of many aspects of the immune system in both animals and humans.” Click To Tweet
The best vegan sources of Selenium
- Brazil nuts
- sunflower seeds
- oat bran
- wheat bran
- rice bran
- fortified breads
Other selenium sources include caviar, liver, shellfish (oysters, whelk, mussels), fish, bacon, pork chops, shrimp (prawns, camarones), lobster and crab. It should be noted, however, that you can get far more selenium from a handful of Brazil nuts than from any of these animal sources.
Zinc may be even more critical to immune system functioning than the other nutrients. According to the American Journal of Clinical Nutrition,
“Zinc is known to play a central role in the immune system, and zinc-deficient persons experience increased susceptibility to a variety of pathogens. The immunologic mechanisms whereby zinc modulates increased susceptibility to infection have been studied for several decades. It is clear that zinc affects multiple aspects of the immune system, from the barrier of the skin to gene regulation within lymphocytes. Zinc is crucial for normal development and function of cells mediating nonspecific immunity such as neutrophils and natural killer cells. Zinc deficiency also affects the development of acquired immunity by preventing both the outgrowth and certain functions of T lymphocytes such as activation, Th1 cytokine production, and B lymphocyte help.”3
Following studies corroborated the 1998 study’s findings.
In 2006, a study published in Annals of Nutrition & Metabolism stated
“… zinc undernutrition or deficiency was shown to impair cellular mediators of innate immunity such as phagocytosis, natural killer cell activity, and the generation of oxidative burst. therefore, both [vitamin C and zinc] play important roles in immune function and the modulation of host resistance to infectious agents, reducing the risk, severity, and duration of infectious diseases.”4
Without sufficient zinc, in the diet, our health and ability to function normally, and even to procreate3, are severely compromised.Without sufficient zinc, in the diet, our health and ability to function normally, and even to procreate, are severely compromised. Click To Tweet
The best vegan sources of Zinc
- whole grains
- wheat germ
- dried watermelon seeds
- pumpkin and squash seeds
- dark chocolate
- cocoa powder
- fortified cereals
Other zinc sources include dairy products and meats like lamb (mutton), crab, roast beef, veal liver, and oysters.
Antioxidant phytonutrients are outstanding immunity enhancers. There are more than 25,000 kinds of phytonutrients5, including carotenoids (mentioned in part 1), polyphenols and flavonoids, which we’ll explore further here. Phytonutrients, as the name suggests, can only be found in plants. Phytonutrients are essentially a chemical defense mechanism that protects plants against bugs, fungi, germs and more. When we eat fruits and vegetables we acquire some that defensiveness. Phytonutrients are even more sensitive to heat than most vitamins, which means we must eat our produce raw to reap the benefits of phytonutrients. The most renowned immunity enhancing phytonutrients are Quercetin and Luteolin.
Quercetin is an excellent inflammation fighter. It has also been found to reduce allergies and boost the immune response. In one mice study, published in Nutrition Research and Practice, it was shown that quercetin could counteract the inflammation and immune system issues caused by radiation treatments.
Quercetin is an excellent inflammation fighter. It has also been found to reduce allergies and boost the immune response. Click To Tweet
“Radiation used in cancer treatment may cause side effects such as inflammation. Quercetin is a polyphenol that reduces inflammation. This study evaluated the recovery efficacy of quercetin on impaired immune function in irradiation-induced inflammatory mice. … The quercetin treatment helped recover the cytokine levels at the lower dose of supplementation (i.e., 10 mg/kg bw oral administration) in the irradiated mice. However, the effective quercetin dose may differ depending on physical parameters. In conclusion, the results of this study verify that quercetin increased immune function, relieved inflammation, and enhanced nutritional status in irradiated mice.”6
Other studies have demonstrated quercetin’s ability to significantly strengthen immunity in both Humans and animals exposed to the flu virus, even if exposure follows stressful exercise.7
Quercetin can be found in the skin of …
- red and black grapes
Quercetin is also found in onions, capers, lovage, chamomile tea, green tea as well as other foods and beverages.
Multiple studies have shown that luteolin, in addition to boosting immune system response, acts as an active “scavenger” of free radicals and may help protect the body against the damage of radiation and chemotherapy.8 This isn’t surprising, as luteolin is structurally related to its fellow phytonutrient quercetin.
According to a study published in the medical journal Current Cancer Drug Targets,
Luteolin's anticancer property is associated with the induction of apoptosis, and inhibition of cell proliferation, metastasis, and angiogenesis. Click To Tweet
“Plants rich in luteolin have been used in Chinese traditional medicine for treating various diseases such as hypertension, inflammatory disorders, and cancer. Having multiple biological effects such as anti-inflammation, anti-allergy and anticancer, luteolin functions as either an antioxidant or a pro-oxidant biochemically. The biological effects of luteolin could be functionally related to each other. For instance, the anti-inflammatory activity may be linked to its anticancer property. Luteolin’s anticancer property is associated with the induction of apoptosis, and inhibition of cell proliferation, metastasis and angiogenesis. Furthermore, luteolin sensitizes cancer cells to therapeutic-induced cytotoxicity through suppressing cell survival pathways such as phosphatidylinositol 3′-kinase (PI3K)/Akt, nuclear factor kappa B (NF-κB), and X-linked inhibitor of apoptosis protein (XIAP), and stimulating apoptosis pathways including those that induce the tumor suppressor p53. These observations suggest that luteolin could be an anticancer agent for various cancers.”8
To clarify, apoptosis is the process of programmed cell death (PCD). Apoptosis is what is suppose to happen when cells mutate. When apoptosis doesn’t occur, the result is either a benign tumor or cancer. Cancer requires angiogenesis, the development of new blood vessels, to fuel its growth and dispersion throughout the body. This is why anemia (abnormally low hemoglobin levels) is a symptom of cancer. Angiogenesis is why cancers spread so quickly. So, you can understand why researchers are excited about luteolin.
Luteolin is found most abundantly in …
- green bell peppers
- artichoke leaves
- fresh thyme
- fresh peppermint
Luteolin can be found in other fruits, vegetables and herbs, but the aforementioned foods contain the highest concentrations.
How much of these nutrients do we need?
Selenium – 55 mg. For both men or women
Zinc – 11 mg. for men, 8 mg. for women. If you’re a strict vegetarian, you may require as much as 50% more dietary zinc, because your body absorbs less zinc when you have a diet rich in plant-based foods.
Unfortunately, there is no RDA (recommended daily allowance) for any flavonoids, so there’s no clear-cut amount of Quercetin or Luteolin you should aim for. In addition, there is no phytonutrient database letting us know how much of each phytonutrient is in each food. This all creates a bit of a challenge. Knowing all this, it’s best to aim for a percentage of raw food intake. for example, and this is just an example: if 50% of your total daily calorie intake comes from raw fruits and vegetables you could be fairly certain that you were getting enough phytonutrients, of all kinds, to reap the associated benefits.
Eating large amounts of raw fruits and vegetables may sound inconvenient, but when you consider how much time you’ll save on food prep and cooking, not to mention the amount of money you’ll save on nutritional supplements and medical bills, it’s actually more advantageous than eating cooked foods. Consider it a form of insurance, or an investment in your longevity.
Our immune system is a highly complex mechanism; it has yet to be fully understood and explained by scientists, but one thing is abundantly clear: we can greatly increase its efficiency and maintain our good health by eating a high nutrient diet. You don’t have to become a 100% raw vegan, or even a vegan, to benefit. Adding more fresh whole foods to your diet can make a significant difference. One of the main benefits of eating raw whole foods is that you will preserve and consume more of the nutrients that bolster immunity. If you feel that you absolutely must cook some of your fruits and veggies, remember, steaming and boiling have been shown to preserve more of the nutrients than other cooking methods.
If you’re not sure how to add these foods to your diet and lifestyle in a balanced and healthy way, I advise you to seek the services of a licensed nutritionist or save money by using an online meal planning service like PlateJoy. PlateJoy employs licensed nutritionists and if you have the good insurance they’ll happily foot the bill. You can learn more about PlateJoy on our Resources page.
1 Arthur, John R, McKenzie, Roderick C and Beckett, Geoffrey J, The American Society for Nutritional Sciences. “Selenium in the Immune System”. The Journal of Nutrition, May 1, 2003
2 Broome, Caroline S, McArdle, Francis, et al, The American Society for Clinical Nutrition. The American Journal of Clinical Nutrition, July 2004. Web. July 24, 2015
3 Shankar AH and Prasad AS. The American Society for Clinical Nutrition. “Zinc and immune function: the biological basis of altered resistance to infection”. The American Journal of Clinical Nutrition, August 1998. Web. July 24, 2015
4 Wintergerst ES, Maggini S and Hornig DH. “Immune-enhancing role of vitamin C and zinc and effect on clinical conditioner”. Annals of Nutrition & Metabolism, December 21, 2006. Web. July 24, 2015
5 “Phytonutrients”. WebMD, October 29, 2014. Web. July 25, 2015
6 Jung JH, Kang JI and Kim HS. “Effects of quercetin on impaired immune function in mice exposed to irradiation”. Nutrition Research and Practice, August 2012. Web. July 25, 2015
7 Davis JM, Murphy EA, McClellan JL, et al. “Quercetin reduces susceptibility to influenza infection following stressful exercise”. American Journal of Physiology, Regulatory, Integrative and Comparative Physiology, August 2008. Web. July 25, 2015
8 Lin Y, Shi R, et al. “Luteolin, a flavonoid with potential for cancer prevention”. Current Cancer Drug Targets, November 2008. Web. July 25, 2015
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