Vegetarian and Vegan Diets, Part 3: Other Nutrient Deficiencies ...

Vegetarian and Vegan Diets, Part 3: Other Nutrient Deficiencies
Vegetarian diets: Other nutritional shortcomings
You don’t have to look any further than the ADA’s Position Statement28 or the USDA’s recommendations on vegetarian diets142 to discover additional nutrient shortcomings caused by pure plant-based diets. The ADA matter of factly mentions that “…key nutrients for vegetarians include protein, n-3 fatty acids, iron, zinc, iodine, calcium, and vitamins D and B12..“28 The USDA notes that “…vegetarians may need to focus on…iron, calcium, zinc, and vitamin B12.”142
These subtle admissions of potential nutrient deficiency problems associated with vegetarian diets represent just the tip of the iceberg. There is little scientific evidence to show that people eating a lifelong plant-based diet can achieve adequate dietary intakes of omega-3 fatty acids (EPA and DHA), iron, zinc, iodine, calcium, vitamin D, vitamin B6 and taurine, an amino acid (without taking supplements or eating fortified foods).
Mineral deficiencies and vegetarian diets
One of the major issues assessing whether any diet provides sufficient nutrients has to do with whether or not the vitamins and minerals measured in certain foods actually get absorbed into our bodies. This is called the bioavailability of vitamins and minerals in foods. A food may contain a particular essential nutrient, but it isn’t bioavailable if we can’t absorb and use it.
Phytate, which is found in some plant foods, prevents the absorption of essential minerals. Whole grains and legumes are sources of phytate. Accordingly, our bodies have difficulty extracting certain minerals from these foods because they are tightly bound to phytate. Phytate in whole grains impairs calcium absorption and may adversely affect bone health. Further, phytate also binds zinc, iron, and magnesium, thereby interfering with their assimilation and incorporation into our cells.
Because vegetarian diets are very hard to follow without including lots of whole grains, beans, soy, and legumes, they are inherently high in phytate. This is why it is difficult or impossible for vegetarians and vegans to maintain adequate body stores of calcium, zinc, and iron.
Zinc Deficiencies in Vegetarian Diets
In part 2 of this series, we discussed how zinc is crucial for normal male reproductive function. However, it is also required for good health and disease resistance in virtually every cell in our bodies, whether you are a man, woman, or child.20, 41
If you have ever experienced painful cracked heels or nose bleeds that just wouldn’t stop, try rubbing zinc oxide ointments on these wounds – you will be amazed at how rapidly zinc can heal these stubborn sores. For many, diet is causing marginal zinc status and deficiencies. Anybody eating excessive whole grains and/or legumes and not eating meat, fish or animal products on a regular basis45, 59, 62 puts themselves at risk for all illnesses and health problems associated with borderline or deficient zinc intake.
Iron Deficiencies in Vegetarian Diets
Your body stores of iron run hand-in-hand with zinc. The same types of diets that produce zinc deficiencies – high phytate vegetarian diets based upon whole grains, beans, soy and other legumes – also create iron deficiencies5, 135 which are the most common nutrient deficits worldwide.
In the U.S. 9% of all women between 12 and 49 years are iron deficient, while 4% of 3 to 5 year old children have insufficient stores of this crucial mineral.25 If you are pregnant, low iron status increases your risk of dying during childbirth, and frequently causes low birth weights and preterm deliveries.
Even more disturbing is the potential for iron deficiencies to prevent normal mental development in our children and young adults.39, 90, 96 Plant based diets not only increase the risk of impaired cognitive function in your children, but will hamper your own mental functioning. Numerous experimental studies show that inadequate iron stores in adults can slow or impair tasks requiring concentration and mental clarity.73
One of the most impactful consequences of diets that cause iron deficiencies is that they make us fatigued and tired. If you are an athlete or have a demanding job requiring physical exertion, low iron stores will invariably reduce your performance. A recent (2009) experiment involving 219 female soldiers during military training showed that iron supplements increased performance for a 2 mile run and enhanced mood.92 Similarly a study by Dr. Hinton and colleagues demonstrated that iron supplements in iron deficient male and female athletes improved endurance performance and efficiency.56
Whether you are an athlete, a laborer or even an office worker, your best nutritional strategy to improve iron stores, add vigor to your life and improve performance is to eliminate whole grains and legumes from your diet by adopting The Paleo Diet.
As always the devil is in the details when it comes to getting correct answers to nutritional questions. There are scientific papers showing no difference between blood iron concentrations in vegetarians and meat eaters. But, what is important is how iron measurements were performed in these experiments. This information is absolutely essential to know if iron deficiencies exist or not. Any study examining blood levels of iron in vegetarians using either measurements of hemoglobin (an iron carrying substance in red blood cells) or hematocrit (the concentration of red blood cells) are unreliable indicators of long term iron status. A much better marker is an iron carrying molecule called ferritin.75 Virtually all epidemiological (population) studies of vegans or ovo/lacto vegetarians show them to be either deficient or borderline iron deficient when blood ferritin levels are measured.
When women were placed on lacto/ovo vegetarian diets, their intestinal iron absorption was reduced by 70%. Inexplicably, blood ferritin levels did not decline for the group as a whole, but it should be noted that nearly half of the subjects did experience drops in blood ferritin concentrations. You recall from earlier in this essay that vegetarian diets caused 7 out of 9 women to stop ovulating. With the cessation of menstrual periods, monthly blood loses also cease which in turn prevents monthly iron losses because blood is a rich source of iron. In any study evaluating blood iron stores in women, it is absolutely essential to know if their normal menstrual cycles were altered. Unfortunately, The study’s lead author, Dr. Hunt, did not provide us with this information, thereby making the correct interpretation of her experiment difficult or impossible..63
Iodine Deficiencies in Vegetarian Diets
A number of studies have reported that vegetarian and vegan diets increase the risk for iodine deficiency.40, 77, 102, 153 One study from Europe demonstrated that 80% of vegans and 25% of ovo/lacto vegetarians suffered from iodine deficiency.77
Additionally, a dietary intervention by Dr. Remer and colleagues in 1999 confirmed this epidemiological evidence.102 After only five days on ovo/lacto vegetarian diets, iodine status and function became impaired in healthy adults.102 The primary reason why vegetarian diets cause iodine deficiencies is that plant foods (except for seaweed) are generally poor sources of iodine compared to meat, eggs, poultry and fish. Gross deficiencies of iodine cause our thyroid glands to swell producing a condition known as goiter. Worse, iodine deficiency in pregnant women can result in severe birth defects called cretinism.141
Because salt is fortified with iodine, most people in the U.S. and Europe rarely develop gross iodine deficiencies.40, 140, 141 However moderate to mild iodine deficiencies appear in westernized countries, particularly among vegetarians and vegans.77, 102 Moderate iodine deficiency impairs normal growth in children and adversely affects mental development.140, 141, 152 A large meta analysis revealed that moderate childhood iodine deficiency lowered I.Q. by 12-13.5 points.153 Paleo Diets are not just good medicine for adults, but they also ensure normal physical and mental development in our children because of their high iodine content.
One of the problems with plant based diets is that they may put into play a vicious cycle that makes iodine deficiencies worse. When the thyroid gland’s iodine stores become depleted, certain antinutrients found in plant foods can gain a foot hold and further aggravate iodine shortages.
Soy beans and soy products are frequently a mainstay in vegetarian diets. They can promote inflammation66 and unfortunately soy contains certain antinutrients (isoflavones) that impair iodine metabolism in the thyroid gland.43, 95 But, this only happens when our body stores of iodine are already depleted.
So, plant based diets start by putting us at risk for developing iodine deficiencies and when this happens our bodies become vulnerable to plant antinutrients that worsen the pre-existing deficiency. The important point here is that antinutritional compounds have virtually zero effect upon our thyroid gland when our body stores of iodine are normal and fully replete. Because meats, fish, eggs and poultry are rich sources of iodine, you will never have to worry about this nutrient when you eat Paleo style.
Vitamin D and Vitamin B6 Deficiencies in Vegetarian Diets
In my paper, Cereal Grains: Humanity’s Double-Edged Sword, I have pointed out how excessive consumption of whole grains adversely affects vitamin D status in our bodies.148 Hence vitamin D deficiencies run rampant in vegetarians worldwide because it is nearly impossible to become a full-fledged vegetarian without eating lots of grains.
In the largest study of vegetarians ever undertaken (The Epic-Oxford Study), Dr. Crowe and fellow researchers reported that blood concentrations of vitamin D were highest in meat eaters and lowest in vegans and vegetarians.29 Nearly 8% of the vegans maintained clinical deficiencies of vitamin D.
Vitamin D is not really a vitamin at all, but rather a crucial hormone that impacts virtually every cell in our bodies.
Vegan or vegetarian diets also frequently cause vitamin B6 deficiencies. On paper, it would appear that vegetarian diets generally meet daily recommended intakes for vitamin B6. This assumption comes primarily from population surveys examining the foods that vegans and vegetarians normally eat. In contrast, when blood samples are analyzed from people relying upon plant-based diets, they reveal that long term vegetarians and vegans are frequently deficient in vitamin B6.
A recent study of 93 German vegans by Dr. Waldman and colleagues showed that 58% of these men and women suffered from vitamin B6 deficiencies despite seemingly adequate intakes of this essential nutrient.131 It turns out that the type of vitamin B-6 (pyridoxine glucoside) found in plant foods is poorly absorbed.47, 103 The presence of pyridoxine glucoside in plant foods along with fiber has been reported to reduce the bioavailability of vitamin B6 so that only 20 to 25% is absorbed and completely utilized.47
In contrast, vitamin B6 found in animal foods is easily assimilated, and an estimated 75 to 100% fully makes its way into our bloodstreams.47
Dr. Leklem’s laboratory at Oregon State University provided compelling evidence that vegetarian diets relying upon the plant form of vitamin B6 adversely affect their body’s overall vitamin B6 stores.47 Nine women were put on diets either high or low in the plant form of vitamin B6 (pyridoxine glucoside). After only 18 days, the high pyridoxine glucoside diets (the plant form) consistently lowered blood concentrations and other indices of vitamin B6 status.
Deficiencies in B6 elevate blood homocysteine concentrations and increase our risk for cardiovascular disease similar to shortages of folate and vitamin B12. Further, vitamin B6 is an important factor in normal immune system functioning149 and shortfalls of this crucial nutrient have been identified in depression150 and colorectal cancer.151
Omega-3 Fatty Acid Deficiencies in Vegetarian Diets
A few years ago I was involved in a series of experiments here at Colorado State University in which we were interested in determining how high- and low-salt diets affected exercise-induced asthma. Our working hypothesis was that high-salt diets would make measures of lung function worse, and low-salt diets would improve things. One of our concerns with this experiment was to somehow make sure our subjects had fully complied with either the high- or low-salt diets. Completely removing salt from your diet isn’t easy to do, and if some of our subjects had decided to sneak in a piece of pizza or some Doritos, it would mess up the experiment’s outcome.
Fortunately, there was an easy way to figure out if our subjects had been compliant with the prescribed diets. All we had to do was to spot check their urine, because measurement of urinary salt levels is an accurate gauge of dietary salt consumption. High urinary salt levels universally reflect high salt consumption, whereas low urinary salt concentrations indicate low salt consumption. Short of major disease, there is virtually no other way high amounts of salt in the urine don’t indicate high amounts of salt in the diet.
In a similar manner, there are equivalent telltale indicators of omega-3 fatty acids in our bloodstreams that tell us beyond a shadow of a doubt whether or not we have regularly consumed fish, seafood or other good sources these healthful fats.
The three main types of omega-3 fatty acids we need to concern ourselves with are EPA, DHA and ALA. EPA and DHA are called long chain omega-3 fatty acids and are only found in high amounts in fish, seafood, certain meats, and other foods of animal origin. Plant foods contain no EPA or DHA. They contain ALA which is a short chain fatty acid that can also be found in animal foods.
Both EPA and DHA in our red blood cells are markers of these important long chain omega 3 fatty acids in our diet. Without good dietary sources of EPA and DHA, our blood levels of EPA and DHA will decline. It is virtually impossible to achieve high blood levels of EPA and DHA without regularly consuming fish, seafood and certain meats and organ meats (particularly grass produced meats and organ meats).
One of the major nutritional shortcomings in vegans is that they obtain absolutely no EPA or DHA from their diets.108, 110, 111 Consequently, they are totally dependent upon plant based ALA, supplements, or fortified foods to obtain these healthful long-chain omega-3 fatty acids. So without supplements or fortified foods, all vegans will become deficient in EPA and DHA because plant based ALA is inefficiently converted into these long chain fatty acids in our bodies. The liver converts less than 5% of ALA into EPA and less than 1% of ALA into DHA.15, 97
Virtually every epidemiological study that has ever been published shows that vegans, who do not supplement or consume long chain omega-3 fortified foods, to be deficient in both EPA and DHA76, 88, 108, 110, 111 Lacto/ovo vegetarians don’t fare much better because milk and egg based vegetarian diets simply do not supply sufficient DHA or EPA to maintain normal blood concentrations.88, 111
Perhaps the single most important dietary recommendation to improve your health and prevent illness is to increase your dietary intake of EPA and DHA. Deficiencies in DHA and EPA represent a potent risk factor for many chronic diseases. Thousands of scientific papers covering an assortment of diseases clearly show the health benefits of these fatty acids. In randomized clinical trials in patients with pre-existing heart disease, omega-3 fatty acid supplements significantly reduced cardiovascular events (deaths, non-fatal heart attacks, and non-fatal strokes).19, 48, 138
Omega-3 fatty acids lessen the risk for heart disease through a number of means including a reduction in heart beat irregularities called arrhythmias, a decrease in blood clots, and reduced inflammation which is now known to be an chief factor causing atherosclerosis or artery clogging.
Taurine deficiencies in Vegetarian Diets
Taurine is an amino acid (actually a sulfonic acid because it lacks a carboxyl group) in our bloodstreams that has multiple functions in every cell of our bodies. Unfortunately, this nutrient is not present in any plant food and is found in low concentrations in milk (6 mg per cup).80 In contrast, all flesh foods are excellent sources of taurine.80 For example, a ¼ pound of dark meat from chicken provides 200mg of taurine. Shellfish are even richer still with over 800mg per quarter pound.
The daily taurine intake in non-vegetarians is about 150mg, whereas lacto/ovo vegetarians take in about 17mg per day, and vegans get none. Although our livers can manufacture taurine from precursor molecules, our capacity to do so is limited – so much so that this amino acid is regularly fortified in infant formulas.
As you might expect, studies of vegans show that their blood taurine levels are lower than meat eaters.81, 100 How depleted blood concentrations of taurine affect our overall health, is not entirely understood. Nevertheless, shortages of this amino acid and omega 3 fatty acids (EPA and DHA) may cause certain elements (platelets) in our blood to clot more rapidly which in turn increases our risk for cardiovascular disease.85, 91 Despite their meat free diets, vegetarians almost always exhibit abnormal platelets that excessively adhere to one another.
In one dietary intervention, Dr. Mezzano and colleagues demonstrated that after eight weeks of EPA and DHA supplementation normal platelet function was restored in a group of 18 lacto/ovo vegetarians.8 Compromised taurine status will never be a problem when you follow The Paleo Diet, because meat, fish, poultry, and animal products are consumed often.
If you have adopted, or are considering adopting a plant-based diet for reasons of improving your health, make sure you reread this series of articles and look up all of the references I have provided you. The evidence that vegetarian and vegan diets can cause a multitude of nutritional deficiencies is overwhelming and conclusive. Over the course of a lifetime, vegetarian diets will not reduce your risk of chronic disease and will not allow you to live longer. Rather, this abnormal way of eating will predispose you to a host of health problems and illnesses. Vegetarianism is an unnatural way of eating that has no evolutionary precedence in our species. No hunter-gatherer society ever consumed a meatless diet.
The Paleo Diet has been criticized and labelled a fad diet because it eliminates “two entire food groups” (grains and dairy). Yet, vegan diets also eliminating two food groups (dairy, meats and fish) and often escape the same criticism. If The Paleo Diet is a fad diet, then it is the world’s oldest.
90. McCann JC, Ames BN. An overview of evidence for a causal relation between iron deficiency during development and deficits in cognitive or behavioral function. Am J Clin Nutr. 2007 Apr;85(4):931-45.