One of the most successful propaganda campaigns within health care in the last few decades has been the re-branding of nutrition as “alternative” or out of the mainstream of scientific medicine. I have marveled at how successful this campaign has been, despite all the historical evidence to the contrary. I suppose this is partly a manifestation of the public’s short-term memory, but it also seems to reflect basic psychology.
There is evidence that most ancient cultures recognized the importance of diet in health. The Greeks recognized both the benefits of a varied diet and the negative health consequences of obesity, for example. But knowledge of nutrition was limited to these broad observations and was mixed with superstition and cultural beliefs.
The science of nutrition probably dates back to 1614 when scurvy (the disease that results from vitamin C deficiency) was first recognized as a dietary deficiency, one that could be cured by eating fresh fruits and vegetables. In 1747 Lind conducted what might be the first clinical trial – systematically comparing various diets for the treatment of scurvy and finding that citrus fruits were the key to treatment.
From 1928 to 1933, two research teams independently isolated ascorbic acid (the chemical name for Vitamin C): a Hungarian research team of Joseph L Svirbely and Albert Szent-Györgyi and the American researcher Charles Glen King. Albert Szent-Györgyi was awarded the 1937 Nobel Prize in Medicine for his part in the discovery.
Prior to that, in 1912, Casimir Funk developed the concept of vitamins (so named because he thought that chemically they were all amines – therefore “vital amines” or vitamins). Vitamins are not, it turns out, all amines, but are defined as micronutrients that are essential for biological function but cannot be sufficiently synthesized by an organism and therefore must be obtained in the diet.
Other components of a healthful diet include other micronutrients, such as minerals and trace elements, and the macronutrients – those that give us our calories and major building blocks. The macronutrients include carbohydrates, fats, and proteins.
Nutrition in Medicine
There have been three major conceptual trends (not mutually exclusive) in the thinking about nutrition in medicine and health. The first was the concept of deficiency – that an insufficient amount of a critical nutrient can cause disease. Nutrition science and intervention in the 19th and earth 20th centuries focussed on malnutrition, identifying specific nutrients and the diseases caused by their dearth, and on the role of supplementation in public health. This approach resulted in iodine in salt, vitamin D in milk, and on the recommended dietary allowances (which are basically the minimum necessary to avoid deficiency).
As an extension of the malnutrition model was the recognition that certain disease states or situations come with increased nutritional requirements. For example, when battling cancer individuals typically have significantly increased nutritional and caloric demands. Increased nutrition may therefore stave off weight loss as a result of the cancer, and help fight off the disease and weather the stress of chemotherapy. It is also recognized that wound healing after injury or surgery requires vitamin C in particular and increased nutrition in general.
In the latter half of the 20th century and continuing into the 21 century science-based nutrition has added two new conceptual frameworks. The first is thinking about excess nutrition – meaning getting too much of something in our diets as a risk factor for disease. Here the focus has been on the macronutrients – too much of the wrong kind of fat as a risk factor for vascular disease and too many carbohydrates as a risk of Type II diabetes are prominent examples. But also too much salt as a risk for hypertension, and even the possibility of too much iron in the diet of men and non-menstruating women.
The other concept that has been added to the scientific approach to nutrition is the recognition that specific nutrients may decreased the risk of developing certain diseases and may even treat an existing disease. To give some examples from my own specialty – vitamin B2 and Coenzyme Q10 have been shown to reduce migraines, vitamin B6 may be helpful in nerve healing (for example from carpal tunnel syndrome), and folate is essential for pregnant women to reduce the risk of spina bifida.
Therefore, to summarize, science-based nutrition includes the recognition of nutritional deficiencies, the increased need for nutrition in situations of physiological stress, the risks of dietary excess, and the role of specific nutrients in mitigating specific diseases and conditions. This is all part of standard medical training, ongoing medical research, and everyday practice. The examples I gave above are meant to be representative, and not exhaustive. Also, specific conclusions are tentative and will change as new data is gathered.
Nutritional claims are prominent among health products and services that lie outside of science-based medicine. Part of the reason for this is regulatory – supplements are often regulated as food, rather than as drugs, and therefore subject to less regulation and oversight. Nutritional supplementation is also highly marketable, because it seems less invasive and less risky than other modalities.
There are many legitimate health benefits for specific nutrients. However, the claims for nutritional therapy often go far beyond the evidence or scientific plausibility. Some promoters go as far as to claim that poor nutrition is the cause of most or even all disease and illness, and therefore all human disease can be treated with supplementation.
Because such claims are not supported by current science, it seems that the industry has decided to make a pre-emptive strike against scientific criticism. Therefore they have created, as part of their marketing strategy, the notion that the medical community does not understand, value, or study the role of nutrition in health. Some even go as far as to claim that there is a conspiracy to conceal real scientific information about nutrition.
Nutrition is an essential part of health and medicine, and nutritional science is a vibrant and successful research program. However, nutrition is also a common target of dubious marketing and harmful medical pseudoscience. Readers are encouraged to have healthy skepticism toward nutritional claims that seem to good to be true, take a hostile approach toward mainstream science and medicine, and especially those that claim there is a conspiracy to silence the truth about nutrition.