Nutrition 101: physicians can no longer ignore the healing power of diet and nutritional supplements

Figure 1. A fish oil supplement providing 850 mg of docosahexaenoic acid (DHA) plus eicosapentaenoic acid (EPA) daily reduced all-cause mortality and sudden death by 21 and 44%, respectively, in this study of over 11,000 survivors of a myocardial infarction.

Data from [9].

Figure 2. A meta-analysis of vitamin D supplementation trials showed a significant decrease in all-cause mortality.

CI: Confidence interval.

Data from [12].

After graduating from high school, I spent the next 15 years of my life enrolled in educational programs designed to provide me with the knowledge base and skill set necessary to become a physician certified to diagnose and treat cardiovascular (CV) diseases. Embarrassingly, over that decade and a half I learned virtually nothing about the role of diet in treating and preventing disease. Indeed, the average physician is relatively ignorant about nutrition’s role in human health unless he or she has taken a personal interest in the topic.

Hippocrates, the physician who is considered the father of medicine, taught “Let food be thy medicine”. That injunction is even more relevant today than it was 2500 years ago. At least 80% of the CV diseases that have become endemic in westernized cultures are a direct consequence of a diet and lifestyle that are increasingly at odds with the nutritional patterns and living conditions for which we remain genetically adapted. Approximately 70% of Americans are now overweight or obese, the lifetime incidence of hypertension is 90%, diabetes or prediabetes affects 36% of adults, and CV disease kills almost half of us [1]. As physicians we have an ever-expanding armamentarium of pharmacologic agents to combat these maladies, but relying exclusively on drug therapy to treat epidemics caused by a maladaptive diet is less rational than simply realigning our eating habits with our physiological needs.

The root cause of modern diseases & the simple dietary solution

Excessive ingestion of calorie-dense, easily digestible, processed foods and beverages causes supraphysiologic surges in blood glucose and triglycerides. These pathological spikes correlate directly with the production of free radicals, such as the super oxide anion. This diet-induced oxidant stress stimulates systemic inflammation, and is a fundamental driver in both the development of CV risk factors and subsequent adverse CV events [2]. Eating patterns such as the traditional Mediterranean or Okinawan diets have been shown in both epidemiological and experimental studies to improve CV risk factors, reduce inflammation, and improve CV health and prognosis [2]. In the randomized, controlled Lyon Diet Heart study, the Mediterranean-type diet caused a 50–70% reduction in major adverse CV events during a mean of 4 years of follow-up after an index myocardial infarction, despite having no effect on the blood cholesterol level [3]. The Mediterranean and Okinawan diets are high in minimally processed high-fiber, plant-based foods such as vegetables, fruits, nuts, legumes and whole grains, with modest amounts of lean protein such as fish. Because they rely heavily on whole, unprocessed fresh foods, these diets are much higher in nutrients and natural antioxidants than the typical Westernized diet. They also induce profound and immediate improvements in the post-meal surges in glucose, triglycerides, blood pressure and inflammation when substituted for the modern highly processed diet [2]. This forager style of eating is closer to the ancient ancestral human diet and should be considered first-line therapy in the treatment and prevention of coronary heart disease risk factors, atherosclerosis and adverse CV events [4]. Physicians, although often unable to personally provide the necessary time and nutritional expertise, should at the very least enthusiastically recommend this anti-inflammatory cardioprotective diet (Box 1)[2], and refer the patient to appropriate resources.

General public vitamania versus physician vitaphobia

For good reasons physicians are generally highly skeptical about the value of nutritional supplements, although many of their patients ingest them by the handful on a daily basis. In recent years, science has generated a steady drumbeat of disappointingly negative results for various nutritional supplements, with sound hypothetical benefits that failed to materialize when subjected to rigors of large, placebo-controlled, randomized trials. A multitude of clinical megatrials testing large daily doses of vitamin E, vitamin C, vitamins B6 and B12, folate, beta carotene and calcium have generally shown no benefit and, in some studies, even have possible harm [5,6]. The evolving evidence indicates that the smartest and safest way to ingest most of our essential nutrients, such as antioxidants, vitamins and minerals, is to consume them as part of a nutritious balanced diet rich in natural whole foods, especially fresh, unprocessed vegetables, fruits, nuts and legumes. Of note, this is the same advice that intuitive and observant mothers have been doling out to their families for centuries.

Scurvy was a common and often fatal disease among the European sailors who subsisted on salted meats and biscuits during long sea voyages in the 15th to 18th Centuries. A Treatise of the Scurvy was published in 1753 by Dr James Lind, a Scottish surgeon in the British Royal Navy, who proved that citrus fruit cured this malady [7]. Lime juice, rich in vitamin C, miraculously banished all of the symptoms of scurvy, including anemia, hemorrhages, gingivitis, bone pain and weakness; and quickly restored the afflicted person to robust health. By contrast, the common practice of ingesting daily mega-doses of vitamin C by a person with a normal baseline vitamin C level has not been proven to confer any health benefit. As a rule, supplementing a deficient level of an essential nutrient back into the normal range typically confers a variety of substantial health benefits, whereas supplementing a normal level into a supraphysiologic range usually results in neutral to occasionally harmful effects.

It is important to note that two essential nutrients are commonly deficient among the American population today; these are omega-3 fatty acids (fish oil) and vitamin D. Not coincidentally, these same two nutrients, when used as dietary supplements, have been shown in large, randomized controlled trials to improve overall health. Our ancient ancestors spent most of their waking hours out in the natural world, where the sunlight stimulated cutaneous vitamin D synthesis. These peoples ate a diet rich in omega-3 fatty acids from fish, wild game, nuts and green leafy vegetables [4]. Today, due to our largely indoor and sun-protected lifestyles, and unnatural diets, we are predictably deficient in vitamin D and omega-3 fatty acids.

Omega-3 for cardioprotection

Harris and colleagues have documented that somewhere between 50 and 90% of American adults have omega-3 levels that are deficient [8]. Over the past 30 years, thousands of epidemiologic, observational, experimental and randomized, controlled studies have been published documenting the CV protective effects of omega-3 fatty acids [9]. The two specific omega-3 fatty acids that have been associated with CV benefit and triglyceride-lowering docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are from fish oils. The most compelling evidence for the cardioprotective effects of omega-3 fatty acids comes from three large randomized controlled trials of 32,000 participants randomized to omega-3 supplements containing DHA and EPA or to control. These trials, showing reductions in CV events of 19–45% (Figure 1), suggest that omega-3 in the form of fish oil supplements should be prescribed routinely, especially for those with, or at risk for, coronary artery disease [9]. Patients should consume both DHA and EPA, in approximately equivalent proportions, with target levels of approximately 1 g/day for those with known coronary artery disease and at least 500 mg/day for those without disease. The American Heart Association has endorsed the use of omega-3 fatty acids for secondary prevention of CV events, and the US FDA has approved a highly purified omega-3 formulation, at a dosage of 4.0 g/day, for the treatment of high triglyceride levels [9].

The most commonly observed adverse effects of omega-3 supplements are nausea, gastrointestinal upset and a ‘fishy burp’. Steps to improve compliance include taking the omega-3 at bedtime or with meals, keeping the fish oil capsules in the freezer or using enteric-coated capsules. One of the potential dangers of a diet high in fish (not fish oil) is the consumption of toxic contaminants, such as methyl mercury. For this reason, the FDA has advised that children and pregnant or nursing women specifically avoid king mackerel, shark, swordfish and tile fish since they are particularly high in mercury. Mercury is water soluble and protein bound and is, therefore, not extracted into fish oils; consequently, fish oil supplements contain negligible amounts of mercury [9].

Vitamin D deficiency: illuminating the darkness

Vitamin D deficiency is a highly prevalent condition, present in approximately 30–50% of the general population [10]. Vitamin D deficiency or in is especially prevalent in elderly, dark-skinned or obese individuals, and those with minimal exposure to outdoor sunshine. However, vitamin D deficiency is also common in practically every segment of the population of the USA, including children and young adults. This endemic deficiency remains generally under-recognized and undertreated.

Severe vitamin D deficiency manifests as rickets in children and osteomalacia in adults; however, a growing body of data suggests that low vitamin D levels may also predispose to a wide range of other diseases. Vitamin D receptors are present in a large variety of cell types, including osteoblasts, myocytes, cardiomyocytes, pancreatic B cells, vascular endothelial cells, neurons and immune cells [10]. Accordingly, vitamin D sufficiency is necessary for the optimal health of most organ systems, and vitamin D deficiency is increasingly recognized as a playing a potential role in the genesis of cancer, multiple sclerosis and diabetes. In the CV system, vitamin D deficiency may predispose to hypertension, metabolic syndrome, left ventricular hypertrophy, congestive heart failure and chronic vascular inflammation [11]. Epidemiologic studies have also recently linked vitamin D deficiency with increased risk of major adverse CV events [11].

In humans, vitamin D is obtained from a combination of sunlight-stimulated cutaneous synthesis, diet and dietary supplements. Traditionally, up to 95% of the body’s vitamin D is synthesized in the dermis upon sun exposure, with the remainder ingested from dietary sources. Most experts define vitamin D deficiency as a 25-hydroxy vitamin D level of less than 20 ng/ml and vitamin D insufficiency as less than 30 ng/ml [10]. The currently recommended daily intake of 200–400 IU of vitamin D daily appears to be inadequate for the maintenance of normal vitamin D levels and optimal health for most individuals. A recent large meta-analysis of placebo-controlled trials showed that supplemental vitamin D improved all-cause mortality when used in doses of at least 400–800 IU daily (Figure 2)[12]. Vitamin D is very safe when used in doses up to 2000 IU daily; and experts now estimate that the target intake for most individuals should be raised to at least 1000 IU daily [11]. The use of vitamin D levels to tailor dosing is very helpful, as the individual response to supplementation can be quite variable.

Summary

Physicians often ignore the importance of diet and nutritional supplements for achieving and maintaining optimal health. The forager-type of diet rich in fresh produce, nuts, legumes, fish and other lean proteins (e.g., egg whites, skinless poultry and whey protein) can dramatically improve health and prognosis. Additionally, many individuals will benefit from daily supplementation of omega-3 fatty acids (fish oil) and vitamin D.

Box 1. Dietary steps to improve postprandial glucose, triglycerides, lower inflammation and improve health.

•	Eat lean protein at all three meals
•	Consume nuts on a daily basis, approximately one handful (with a closed fist). Eat with vegetables, berries or other fruits, or grains
•	Eat a salad of leafy greens dressed with vinegar and virgin olive oil on a daily basis
•	Choose high-fiber, low-glycemic index carbohydrates, such as whole grains, legumes, vegetables and fruits
•	Avoid highly processed foods and drinks, especially those containing sugar, high-fructose corn syrup, white flour or trans-fats
•	Keep serving sizes modest
•	Avoid being overweight or obese; maintain a waist circumference of less than half of height in inches
•	Obtain 30 min or more of daily physical activity of at least moderate intensity
•	Consider consuming one alcoholic drink before or with the evening meal (for those without a history of substance abuse)

Financial & competing interests disclosure

James O’Keefe is an unpaid Consultant to CardioTabs. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed

Writing assistance was utilized in the production of this manuscript. The author would like to acknowledge Lori J Wilson for her assistance with manuscript preparation.