How much of a vitamin do we really need?

When I was growing up in the 50s and 60s, healthy eating was about a balanced diet. We got our nutrients from foods not from vitamin tablets. My dietary pattern included whole and processed foods. Many of those processed foods were ultra-processed in today’s lexicon. We grew fruits and vegetables in our backyard garden. Mother canned and froze the surplus for the brutal Canadian winter. Each lunch and dinner featured meat, potatoes, a vegetable, and dessert. My beverages of choice were chocolate milk and soft drinks. Most of our restaurant meals came on road trips. Our diets filled us with enough, but not too many, calories. Sugars and fats were OK. We consumed enough vitamins and minerals from meat, milk, eggs, and vegetables.

Dietary advice has changed. Society no longer worries about vitamins and minerals. We have supplements for that. We worry about too much fat, salt, and sugar in our foods. We also watch our carbs and calories. When did concerns about undernutrition turn into concerns about overnutrition? When did overconsumption of sugars become more important than overconsumption of fats? When did carbs become more dangerous than calories?

51ngfqm8nps._sx218_bo1204203200_ql40_fmwebp_I am on a quest to gain a greater understanding of vitamins. So much information assaults us on the web about the benefits and dangers of vitamins. I formulated eight questions to help me clarify my understanding of these nutrients. Then I bought and read The Vitamins a recent textbook by Combs and McClung to find answers. Last week I examined supposed differences between natural and synthetic vitamins. This week I delve more into how much we of individual vitamins do we need to stay healthy.

The next two questions in this series are:

3. Do people become sick or die from vitamin deficiencies in the 21st Century? Critics of modern nutrition claim that it focuses too much on nutrients and not enough on food. Further, nutrition ignores traditional culture as a guide to healthier eating patterns. Rather than practicing true nutrition, health professionals practice Nutrtionism. One tenet of these critics proclaims that “Single nutrient deficiency diseases, for example—such as vitamin C deficiency causing scurvy—are now the exception rather than the rule in highly industrialized countries.” From a nutrient standpoint, then, Americans are in good shape. From a health standpoint, we are in trouble. Chronic diseases like diabetes, heart disease, and obesity have become major health concerns. Food has become the culprit for the emergence of chronic disease.

Georgy Scrinis coined the term nutritionism. Michael Pollan popularized it. Scrinis urges us to abandon nutritionism and the processed foods that feed it. Instead, we should embrace “cultural-traditional knowledge” and “sensual-practical experience” for nutritional guidance. Our heritage and palate are more reliable on the value of food. Product labels on processed foods mislead us claim the opponents of nutritionism. I agree with Scrinis that modern society relies on vitamins as magic molecules. But where is the nuance between supplementation and health effects of vitamins? Are vitamins only important in preventing deficiency diseases?

Back to the question about vitamin deficiencies as asked. The Vitamins is a prime example of nutritionism in practice. The book discusses, in detail, roles of vitamins in preventing deficiency diseases. Once the level of a vitamin is so low that a deficiency disease results, we have a nutritional disaster. There are levels between sufficiency and deficiency that matter to health. It is this concept that discussion of nutritionism oversimplifies. More on this topic below, but first let’s turn our attention to ascorbic acid, aka vitamin C.

chemical structure of ascorbic acid
The active form of vitamin C

The story of vitamin C and British sailors is well known. Long voyages on British ships led to scurvy outbreaks. Citrus fruits are good sources of ascorbic acid. By carrying lemons on ships, sailors became less susceptible to the scourge of scurvy. This vitamin has other important roles in the body. First, it functions as an antioxidant. It tag teams with vitamin E to protect cellular membranes. It helps protect cell lipids, proteins, and DNA. Ascorbic acid stabilizes iron in the cells. It also serves as a cofactor in ten critical enzyme reactions.

Low levels of vitamin C in the body compromise many cellular reactions. Ascorbic acid supports immune function, skin health, and wound healing. It plays roles in bone health, cardiovascular health, and muscle function. Before we run out to buy and pop vitamin C tablets, supplements are not miracle workers. We need enough, but more than enough does not enhance these functions. Contrary to popular opinion, excess ascorbic acid is NOT excreted in the urine. Rather some ascorbic acid converts to urinary oxalate stones. Excess levels in the body can lead to vitamin B12 destruction or contribute to iron overload.

4. Why is the difference between the amount of a vitamin needed to prevent a deficiency disease and the RDA so large? It turns out that this was the most important question that I asked. The answer I learned from the book makes it the most meaningful. There are four levels of deficiency when it comes to vitamins. To understand the importance and limitations of vitamins, we must understand these levels. The Vitamins describes them in a clear fashion. None of my nutrition or food science courses ever explained this concept to me. Neither did my reading. Or the idea could have been there, but I was oblivious. Here goes starting with the least serious stage:

  • Gradual depletion of vitamin stores is the first step in vitamin insufficiency. This stage may or may not affect physiological health.
  • Cellular metabolic changes due to vitamin insufficiency affect proper physiological function. The body is now in an unhealthy state. We do not notice a subclinical depletion of a specific vitamin. Only a blood test can determine this level of deficiency.
  • Functional defects are clinical signs that start occurring signaling a vitamin deficiency. They can result from insufficient consumption, digestion, or absorption of the vitamin.
  • A deficiency disease develops when not enough of the vitamin is present to prevent it. Lesions develop. Clinical symptoms associated with that particular vitamin deficiency appear. Treatment measures must occur soon to prevent permanent damage.

There is much more to vitamin deficiency than the classical disease. Few of us will ever experience a deficiency disease or even clinical symptoms. A vitamin, then, loses important functions when stores fall below our needs. Yet, this subclinical deficiency goes undetected. A Facebook discussion on last week’s post revolved around the need for a daily supplement to ensure adequate stores. Another point of contention was whether to encourage everybody to eat healthy. Or do we deal with the reality of what people eat now and find ways for them to get their vitamins? It would be nice that everyone was able to get all the vitamins they needed from foods. A daily supplement of vitamins and minerals could serve as backup for those who don’t eat a healthy enough diet. The problem comes when one overconsumes single-vitamin supplements without medical oversight.

The ideal situation is that we all have enough of each vitamin in our bodies. That does not mean that we need to consume the Daily Value of each vitamin each day. What it does mean that over a period of time we need to maintain our vitamin stores. Then there is the problem of consuming too much of a single vitamin or a daily multi-vitamin tablet. Hypervitaminosis is real. Too much of a vitamin can be toxic or can interfere with proper function of other vitamins. That is why we need to careful of getting too much of a good thing.

Before discussing thiamin levels of sufficiency, I must get back to terminology. So many of us grew up with the RDA (Respective Daily Allowance). Combs and McClung consider the term obsolete. Use of RDAs encourages overconsumption of vitamins. Of particular concern are vitamin A, vitamin D, and niacin. The proper terminology is Daily Value. Packaged food products reflect the use of this term on the Nutrition Facts statement. New guidelines increase vitamins C, D, and K recommendations. Daily Values for Vitamin A and E are now lower. Levels are also lower for niacin, riboflavin, and thiamin.

chemical structure of thiamin
Free base structure of thiamin. Structure courtesy of Dr. Ron Pegg.

Thiamin serves as my model for vitamin insufficiency. The first organ to feel its effects is the brain. Glucose metabolism depends on thiamin. Brain function depends on glucose. Thiamin supports vascular and antioxidant function in cells. Adequate levels help protect against dementia, Alzheimer’s disease, and Parkinson’s disease. Chronic alcohol consumption interferes with proper thiamin absorption. Overweight and obese individuals tend to have lower levels of thiamin in their body. The reason could be a dietary pattern limiting the vitamin. The first clinical signs of insufficient thiamin are loss of appetite and tingling of arms and legs. Beriberi is the classic thiamin deficiency disease. Loss motor function of the nerves characterizes dry beriberi. Damage to the heart leading to cardiac arrest are signs of wet beriberi. There is little evidence of thiamine toxicity. The body excretes excess levels in the urine.

Take-home lesson. Few of us will become a victim of scurvy, beriberi, or other deficiency disease. That does not mean that we are consuming enough ascorbic acid, thiamin, or any other vitamin. Nutritionism causes us to focus on deficiency diseases. But we fail to understand the consequences of less serious levels of insufficiency. The first clinical symptoms of deficiency are not the same as for the deficiency disease. Insufficient levels of vitamin stores affect metabolism and are difficult to diagnose. Remember insufficiency of riboflavin in poor urban males noted last week? Only blood diagnostics can pick up these insufficiencies.

The Vitamins links metabolic health to vitamin sufficiency. It is the proper balance of vitamins in our bodies not only adequate amounts. I see little discussion of these points in popular media. Our hang-ups on clinical deficiency obscure our understanding of how vitamins really function. These hang-ups spur overconsumption in hopes of miracle cures or miracle protection. It is important to replenish water-soluble vitamins in our diets.

Many places around the world incur vitamin deficiencies as a cause of disease and death. Countries with dietary patterns high in ultra-processed foods have few classic deficiency diseases. Vitamin sufficiency is not limited to absence of classic deficiency diseases. Sufficiency relates to metabolic health. We can get our vitamins from a healthy diet or from daily supplements. How do we know if we get enough to meet our daily needs? It is not simple without blood tests. There are also dangers of consuming too many vitamins. I do not take a vitamin/mineral supplement assuming I consume enough dairy, egg, and meat products. I balance out those foods with fiber-rich vegetables and some fruits. Will that be healthy enough? The answer is not as simple as it seems.

Next week: Vitamin potency and toxicity

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