Cod Liver Oil
by Leslie McGee, RN, LAc
No one believes me, but it just flies off the shelf. Cod liver oil, that is. Once my clients recover from their initial horror at my suggestion to take cod liver oil, and then try it for a month, they are always back for more.
My training is in Chinese medicine, and although cod liver oil has its roots in Scandinavia, we can look at any food or supplement through the prism of Chinese medicine theory. As I have learned more about the research on cod liver oil, its traditional uses, and my own clinical experience, I have come to believe that cod liver oil nourishes us at a very deep level.
Chinese medicine is a very old system with its own terminology and theories of health and disease. Yet, in spite of its ancient roots, this system can readily be applied to modern people and modern diseases. Chinese medicine includes its own logically consistent theories of physiology and pathophysiology. Illness, health, foods and medicine, including cod liver oil, can all be described within this framework.
From a Chinese medicine perspective cod liver oil supports the body in three fundamental ways:
- It supplements yin and yang
- It fills the essence
- It strengthens the kidneys
Yin and Yang
Supplementing the body in this way supports our very foundation. Understanding what this means adds to our appreciation of the value of cod liver oil. Let’s examine the Chinese medicine theory behind these concepts: yin and yang, essence and the kidneys.
Most Westerners have heard of yin and yang. These are foundational concepts in Chinese medicine. Yin and yang represent opposite principles–a duality. All life and all creation are manifestations of the interplay between yin and yang. We can apply yin and yang to the body and all physiological processes. Yin is cool, dark, moist, female, still, quiet and substantial. Yang is hot, bright, dry, male, exuberant, energetic and insubstantial. Within our bodies we have yin and yang qualities and functions.
For example, our yin aspect is our literal body form–our bones, muscles and substance. Our yang aspect includes our body’s warmth, movement and energy. Yin represents anabolic metabolism (building form and structure). Yang represents catabolic metabolism (consuming form and creating energy). Adequate yin allows us to rest and sleep deeply. Adequate yang gives us energy, power and motivation.
While opposite, yin and yang are inherently connected. We say yin and yang are mutually consumptive, yet also mutually supportive and mutually transforming. Health requires that our yin and yang be fairly balanced. Appropriate waking and sleeping is the result of the balance and interplay of yin andyang at different times of the day. Aging involves the gradual decline of yin and yang. Death implies the final separation of yin and yang.
As we age, it is not uncommon for yin or yang to decline and become deficient. Because yin and yang play such a fundamental role in our physiology, we find yin or yang deficiencies in a great variety of conditions. When we remember that yin equals coolness, moisture, stillness and substance, we can see that deficiency of yin would create heat, dryness, agitation (lack of stillness) and wasting of body mass (lack of substance). Western diseases or syndromes that may be due to yin deficiency include hot flashes, insomnia, anxiety, attention deficit disorder and osteoporosis.
Similarly, since yang equals heat, energy and activity, deficiency of yang may create cold, fatigue and sluggish metabolism. Western diseases and syndromes that may be due to yang deficiency include hypothyroidism, hypoadrenalism, weight gain, chronic fatigue, weak immunity and depression. It is not uncommon for people to be both yin and yang deficient at the same time. An example of this is a menopausal woman who has hot flashes, but when she’s not having a hot flash, she tends to feel cold and fatigued.
Essence is another idea from Chinese medicine that relates to our fundamental capacities and strengths. Essence refers to one of the body’s five vital substances. The other vital substances are qi (energy), blood, body fluids and shen or spirit. All five vital substances must be present and free flowing in a healthy person, but essence most relates to our very foundation. We inherit essence from our parents, and we also create essence by eating well and living a balanced life. Essence governs our growth and development. Essence gives us our reproductive capacity. As essence declines, our bodies age. Adequate essence is required for fertility and healthy pregnancy. Maintaining essence is a key strategy for promoting longevity.
The third concept applicable to the benefits of cod liver oil relates to the Chinese theory of internal organ function. Many organs are recognized in Chinese medicine, and organ functions are similar to the modern understanding of those organs. However, additional functions are assigned to most organs in the body. In this spirit we describe the kidneys as the home of our basic yin and yang energies, and the home of the essence. According to Chinese medicine, keeping the kidneys strong is an important way to protect and fortify yin, yang and essence. Thus, strengthening the kidneys is a basic strategy for promoting health and longevity.
My conclusion that cod liver oil supplements yin and yang, fills the essence, and strengthens the kidneys is based on my own observations as well as commentary from the Chinese medical literature. For centuries Chinese doctors have been describing foods and medicinal herbs in Chinese medicine terms. This process continues today as Chinese medicine practitioners notice how any ingested substance–food, herb or pharmaceutical–affects the body. Although my English language sources did not reveal a Chinese medicine description of cod liver oil per se, they do provide very interesting descriptions of vitamins A and D, the two-fat soluble vitamins that make cod liver oil so valuable.
Vitamins A and D
According to Chinese medicine, vitamin A “supplements the blood and fills the essence; brightens the eye and clears heat from the blood.” It also treats heat in the body due to a lack of yin.1 (Remember that yin represents coolness, so a lack of yin can create improper heat in the body.) Vitamin D “supplements the kidneys and invigorates yang; strengthens sinew and bone, brightens the eye and quiets the fetus.”1 It is well established in Chinese medicine that high quality fats and oils nourish the yin of the body.2 The fish oil of cod liver oil is such a yin supplement.
The technical language may be a little awkward to Westerners, but the message is clear: vitamin A and fish oil nourish yin, and vitamin D supplements yang. Vitamin A and D arrive together, in nature, a perfect yin-yang pair. It may seem strange that a single food or supplement can nourish both yin and yang, since yin and yang are opposites, but, in fact, a few herbs and foods do just that. And by nourishing yin and yang together we protect ourselves from over-supplementing one or the other. When you only supplement yang, the body can be over-heated and over-stimulated. When you only nourish yin, the body becomes sluggish and prone to weight gain.
When we consider the Chinese medicine description of vitamins A and D, it makes sense that cod liver oil has such deep and global benefits for people. Cod liver oil is an excellent choice for many conditions where yin or yang, or both, are lacking. Yin or yang deficiencies are quite common and occur in a great variety of syndromes or illnesses, especially as we age.
Notice the other comments about vitamin D. Remember, when yin or yang is deficient, we also need to fortify the kidneys. Vitamin D does just that. It is also very interesting to note that vitamin D “quiets the fetus.” This is a technical expression for the idea that some herbs and foods support and protect the fetus and are thus safe, or even required, during pregnancy. Only a handful of Chinese herbs quiet the fetus. We also see that vitamin D “strengthens sinew and bone” and indeed in modern medicine we understand that vitamin D plays a crucial role in bone formation.
In my clinical experience, cod liver oil is extremely helpful in a great variety of conditions, and these conditions can usually be linked to the person’s yin, yang or essence status. I have seen excellent results in clients with weak immune systems. Cod liver oil also has tremendous value in women’s health. It can help normalize the menstrual cycle and eliminates many premenstrual discomforts. Certainly “filling the essence” is critical for improving fertility. And it is interesting to speculate whether menopause would be less of a problem if women used cod liver oil throughout their lives. The description of vitamin A as “supplementing blood and clearing heat due to deficiency”1 is a perfect treatment principle for common menopausal symptoms.
I have seen depression respond very well to cod liver oil. I believe this is because in supplementing both yin and yang the brain and spirit receive both the stability and calmness of yin and the enlivenment of yang. Evidence is growing in modern science for the use of fish oils in many neurological and psychiatric problems.3,4
General inflammation also responds well to cod liver oil. Inflammation is now recognized as a key factor in many diseases, from colitis to arthritis to heart disease. The ability to “clear heat from the blood,” as it is described in the Chinese medical language, may relate to this anti-inflammatory action. The modern research on cod liver oil supports these clinical indications.5
I also find it interesting that when vitamin A or D are given alone problems may ensue, and this is why some modern nutritionists frown on supplementing with the fat soluble vitamins.6 Only in modern times are vitamins A and D delivered as isolated single components. In nature, vitamin A and D arrive together, a perfect yin-yang pair. Hopefully research will explore the idea that this pair of vitamins work best together in their natural state.
Wide Range of Help
How can cod liver oil help people with such a wide range of health issues? I believe it is because yin, yang, and essence support all bodily processes, everything from immunity to mental health to endocrine balance. In my practice it has been very gratifying to see the power of cod liver oil and fascinating to consider the Chinese medicine implications.
I live in Tucson, Arizona and my clients often wonder whether the vitamin D in cod liver oil presents a safety issue for those living in the southwestern US where sunlight is abundant. I tell them it all depends on your exposure to sunlight. If you deliver mail or work outdoors on a ranch or sunbathe routinely, then you would need to be aware of your vitamin D blood levels before taking cod liver oil routinely.7 However, I think most of us spend literally all day indoors, and use sunblock when outdoors, so even in my sunny hometown, a little cod liver oil is safe. I recommend one to two teaspoons per day. Less in the summer if you are outdoors a lot; a little more in the winter. Those who live farther from the equator or who have darker skin may take more. This is very significant for people with dark skin. It has been found that African-Americans are much more likely to be vitamin D deficient.8
It is important to remember that in Chinese medicine supplementing deficiencies is a gentle, gradual process. I ask my clients to try cod liver oil for at least a month, to give it a fair trial, but usually they are believers by then. Analyzing cod liver oil with Chinese medicine theory gives us additional insight into why it is so powerful. Filling the essence, fortifying the kidneys and supplementing yin and yang are excellent strategies for health.
1. Flaws, Bob, The Tao of Healthy Eating: Dietary Wisdom According the Chinese
Medicine, Blue Poppy Press, Boulder, CO, 1998: 60-61.
2. Pitchford, Paul, Healing With Whole Foods: Oriental Traditions and Modern Nutrition,
North Atlantic Books, Berkeley, CA, 1993: 118-119.
3. Stoll, M. et al, Omega-3 fatty acids and bipolar disorder: a review. Prostaglandins
Leukot Essent Fatty Acids. 1999 May-Jun; 60 (5-6): 329-337.
4. Haag, M. Essential fatty acids and the brain. Can J Psychiatry. 2003 Apr; 48 (3):
5. Sullivan, Krispin, Cod Liver Oil – The Number One Superfood. Wise Traditions, 2002; 3
(1): 25 – 33.
6. Meiss, D and Cranton, E. Current recommended safe levels of vitamin A intake do not
cause increased fracture rate. Townsend Letter 2003 July: 84-85.
7. Sullivan, Krispin, The miracle of vitamin D. Wise Traditions. Fall 2000;1(3): 11-20.
8. Nesby-O’Dell, S et al. Hypovitaminosis D prevalence and determinants among
African-American and white women of reproductive age: Third National Health and
Nutrition Examination Survey, 1988-1994. Am J Clin Nutr. 2002 July; 76(1): 187-92.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly
magazine of the Weston A. Price Foundation, Fall 2005.
About the Author
Leslie McGee, RN, LAc, is a registered nurse and a licensed acupuncturist in private practice in Tucson, Arizona. She can be reached at MCQI (at) yahoo.com.