Nutrition and Diet

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Nutrition and Diet2017-11-08T00:38:29+00:00

Nutrition

The history of nutrition can be divided into an era of quasi-experimentation* that ended in the late 19th century. It was followed by the so-called Golden Age of Nutrition which began in the early 20th century with the discovery of all of the known vitamins and recognition of the central importance of trace minerals in physiology. With the benefit of hindsight, we now know that many of the diseases suffered by the ancients were due to a lack of macro- or micronutrients in their diet.  

*Two of the best-known nutritional “experiments” involved sailors: British sailors with scurvy in the 18th century, and Japanese sailors with beriberi in the 19th.  

Macronutrients are required in relatively large amounts and include carbohydrates, lipids (essential fatty acids) and proteins* which are metabolized to form structural components of cells, participate in signaling and hormonal activity and play central roles in intra- and extracellular metabolism. 

*As well as water, and fiber

 Micronutrients include:

• Minerals with a recommended daily allowance of > 150 mg/day–calcium, magnesium, phosphorous, potassium, chlorine, sodium and sulfur (macrominerals)

• Minerals required in trace amounts (< 150 mg/day)–cobalt, copper, chromium, iodine, iron, manganese, molybdenum, selenium, zinc (microminerals)

• Vitamins which are divided into

   – Water soluble–vitamins B1, B2, B6 and B12 and C 

   – Fat soluble–vitamins A, D, E, K

nutrition scurvy image from New Medical Terms

Scurvy in British Navy

Scurvy was the first major disease directly linked to a dietary deficiency, the cure for which is citrus fruit* or, for native Canadians, tea made from the boiled needles of the arbor vitae tree. Several centuries passed before citrus fruit became widely recognized as the cure for scurvy: in 1753, James Lind (1716-1794), a Scottish physician with the British navy, wrote Treatise on Scurvy, a work that reflected his experiments on sailors with scurvy, a disease which Lind asserted had caused more deaths than French or Spanish arms, some 2 million between 1500 and 1800. Unfortunately, his work had statistical “noise” that watered down a definitive link between scurvy and citrus fruit. Lind incorrectly concluded that lack of lemons was one of the causes of scurvy…as opposed to THE cause of scurvy. Eventually, the top brass in the British Navy accepted the link between citrus fruit and scurvy and sailors were issued daily rations of lemon juice, which prevented the disease. 

*A discovery attributed to Portuguese explorer Vasco de Gama in 1497

In the 1800s, beriberi, a condition characterized by weight loss, neuralgia, weakness, limb pain and arrhythmias, and thought to be infectious in nature, was virtually endemic in Japan, and particularly common in sailors. Takaki Kanehiro, a physician in the Japanese Imperial Navy who’d trained at St Tommy’s in London, wondered why beriberi was rare in the navies of other countries and in officers of the Imperial Navy. He learned that the sailors of the Japanese Navy were dirt poor, and were sending what little money they earned home. The sailors had to pay for any food other than polished rice, which was free. The free rice had the thiamin-rich husks removed in processing. Takaki petitioned the Imperial Navy’s muckamucks to improve the sailors’ diet, which eliminated the disease, 10 years before Christiaan Eijkman hypothesized that beriberi was due to a nutritional deficiency and later identified thiamin as the missing factor, for which Eijkman netted the 1929 Nobel Prize in Physiology or Medicine. 

Between 1926 and 1936, all of the vitamins (A, B1–thiamin, B6, biotin, C, D, E, folate, K, niacin, pantothenic acid, riboflavin) were identified and malnutrition addressed in the developed countries–in sharp contrast to developing countries, where malnutrition is still too often the norm. The map confirms what we know intuitively: at least 20% of the children of Africa and the Indian subcontinent are malnourished and in many countries, more than 40% are malnourished. 

The United States Department of Agriculture (USDA) has been involved in fomenting proper nutrition as a public policy since 1894. The first guideline was published as a farmer’s bulletin. It has been followed at various intervals by revisions in name and content to reflect the needs of Americans. From 1956 to 1992, the USDA flogged the basic Four Food Groups, which divided food into vegetables and fruits; milk and dairy; meat; and cereals and breads. 

The Center for Nutrition Policy and Promotion in the USDA and the US Department of Health and Human Services have jointly released Dietary Guidelines for Americans every 5 years since 1980. A key issue with these Guidelines is pressure exerted by the agriculture industry to whitewash language that encourages Americans to cut down on red meat, fats and dairy products and shift consumption to plant-based foods whilst factoring in environmental sustainability. 

nutrition pyramid image from New Medical Terms

USDA food pyramid

Not surprisingly, the Guidelines have been criticized as being heavily influenced by Big Ag and Big Pharma. The Four Food Groups (1956 to 1992), Food Guide Pyramid (1992 to 2011) and MyPlate (2011 to date) schematics simplify these guidelines. 

The Four Food Groups was followed in 1992 by the Food Guide Pyramid which, in its original iteration, placed fruits and vegetables at the base of the pyramid to be consumed ad lib, and meat and dairy at the top. The USDA caved in to pressure by special interest groups in the grain, meat, and dairy industries and put carbohydrates at the very bottom instead of fruit and vegetables and dropped meat and dairy products from the eat sparingly pinnacle and lumped heart-healthy protein foods–e.g., beans, nuts and fish, in with heart-unhealthy red meat. Its value to consumers was further compromised by inclusion of commercial snacks and fast foods.  The healthier Mediterranean Food Pyramid (image) is a popular schematic that addresses the failings of the USDA version. The latest nutritional schematic, My Plate (see image) which the USDA launched in 2011 has addressed some of the criticisms leveled at USDA’s food pyramid. The My Plate graphic indicates that the bulk of one’s food consumption should be fruits, vegetables and grains with the remaining 20% to 30% comprised of dairy and protein-rich foods from which one will obtain one’s proteins and essential fats. 

nutrition Nutrition facts image from New Medical Terms

Nutrition facts

No overview of nutrition would be complete without mentioning Nutrition Facts labels–aka, Nutrition Information Panels, which are found on packaged foods in North America (see image), Europe, in India and Down under. The US established rules for these labels in 1990; they are required for most food products under the Nutrition Labeling and Education Act. The information on them are based on FDA recommendations. The rules languished unchanged for the next 25 years. 

They have been revised to reflect trends in the consumption of nutrients of public health importance, and more importantly, re-designed because studies have shown that most people don’t understand what the hell the label means or, said politely, the nutrition label numeracy is low, in large swaths of the population, in geezers, out-of-workers, non-English speakers, the uneducated, the poor and, here’s a surprise, those living in the South. The label re-design was completed in 2016; the new labels will start going live in mid-2018 and businesses will have until 01.01.2021 to fully comply.

References
http://www.ansc.purdue.edu/courses/ansc221v/histnote.htm

https://en.wikipedia.org/wiki/Nutrition

https://en.wikipedia.org/wiki/Takaki_Kanehiro

https://en.wikipedia.org/wiki/History_of_USDA_nutrition_guides

https://www.cnpp.usda.gov/dietary-guidelines

BMJ 2015;351:h4962

https://en.wikipedia.org/wiki/Nutrition_facts_label

https://www.cnpp.usda.gov/2015-2020-dietary-guidelines-americans