Vegetarian and Vegan Diet (cont.)
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What are the potential health problems from consuming a vegetarian and vegan diet?
Many people believe that it's not possible to consume all of your necessary nutrients without meat in your diet. Vegetarian diets can be nutritionally balanced, but it will take some planning to do this. Numerous studies have shown that poor meal planning is the cause of nutritional deficiencies in vegetarian diets, not the absence of animal foods. Well-balanced vegetarian diets have been approved for all stages of life, including pregnant and lactating women, children, adolescents, the elderly population, and competitive athletes.
The nutrients for which you are at risk of not getting enough will depend on the foods that you have omitted from your diet. The following are the most common nutrients that may be lacking in a vegetarian diet.
Omega-3 fatty acids
The American Heart Association recommends "consuming fish (particularly fatty fish) at least two times a week." The fat in fish provides the essential omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The omega-3 supplements and the foods fortified with it have varying amount of EPA and/or DHA. Omega-3 fatty acids have been shown to slow the progression of atherosclerosis, reduce triglyceride levels, act as an antiinflammatory agent, possibly help with depression and other personality disorders, and possibly thin the blood. There is ongoing research to determine if there are other health benefits.
To a limited extent, your body can produce EPA from alpha-linolenic acid (ALA), another essential fatty acid. According to studies, ALA does not produce any DHA, so it does not provide comparable health benefits to omega-3 fatty acids. ALA can be found in non-meat sources such as flaxseed oil, flaxseeds, canola oil, walnuts, and tofu. Research has shown that microalgae oil can serve as a source of omega-3 fatty acids for vegans and vegetarians. Microalgae oil is rich in DHA like fatty fish and provides an adequate amount of EPA.
One other thing to take into consideration when trying to obtain the health benefits from omega-3 fatty acids is the amount of omega-6 fatty acids that you are consuming. Omega-6 fatty acids are the other essential fat in our diet. These fatty acids are found in abundance in our diets. So much so, that we actually need to cut back on them. Omega-6 fatty acids are found in most vegetable oils, soybean oil, corn oil, sunflower oil, and peanut oil. Some experts state that we currently consume about 14 times more omega-6 than omega-3 fatty acids. The goal is to bring this consumption closer to an equal intake or, at most, only 3 grams of omega-6 fatty acids for every 1 gram of omega-3 fatty acids. Flaxseed oil and flaxseeds are the only source of ALA that does not also provide omega-6 fatty acids.
While there are no official guidelines for how to get an adequate amount of omega-3 fatty acids in a vegetarian diet, there are some recommendations that you can follow:
Vitamin B12 is attached to the protein in animal foods. There has been considerable research to determine if it is also found in some plant foods. Unfortunately, the B12 that has been found in plant foods can't be used by humans. Supplements that have been made with the plant sources have been shown to contain B12 analogues, compounds that are structurally similar to B12 but do not serve the same function. Research has shown that using supplements with these analogues can actually compete with vitamin B12, inhibit its metabolism, and increase the risk of B12 deficiency, a very serious condition that can lead to anemia and irreversible nerve damage.
Vitamin B12 is found in seafood, dairy, eggs, and meat. Vegan diets have the highest risk of deficiency. There are many foods that are fortified with vitamin B12, so it is possible for vegan diets to contain adequate amounts of this nutrient with or without a supplement. The recommendations for reaching your vitamin B12 needs are to
2. take a B12 supplement if you are unable to consume an adequate amount in your diet or if you have an increased need for it (elderly, pregnant, and lactating women),
3. do not take excessive amounts of folate supplements, as this can mask a B12 deficiency, and
4. have your B12 level checked by your physician.
The most well-known source of calcium is dairy foods, which are often omitted or greatly limited in vegetarian diets and are completely omitted in vegan diets. Dairy products provide 70% of the dietary calcium of the U.S. population. The nondairy foods that provide calcium are calcium-fortified tofu, some roots and legumes, and fortified soy milk.
Certain factors will impact how much calcium you actually absorb from the food, such as the amount of calcium that is present and the presence of vitamin D. The presence of vitamin D will enhance absorption, while the presence of oxalic acid and phytic acid will interfere with the absorption. Foods rich in oxalic acid are spinach, rhubarb, sweet potatoes, and beans. Foods rich in phytic acid are unleavened bread, nuts, seeds, and raw beans. You will absorb some of the calcium in foods that you consume when oxalic acid and phytic acids are present but not as much as you would when they are not present. For example, calcium absorption from dried beans is about half of that absorbed from milk, and calcium absorption from spinach is about one-tenth of that from milk.
The following are recommendations for consuming an adequate amount of calcium:
2. Vegans should consume calcium-fortified juices or soy milk on a daily basis, calcium-rich foods throughout the day, and consider taking a daily supplement.
3. Calcium intake needs to be spread throughout the day for optimal absorption. We do not efficiently absorb more than 500 mg at a time, so there is no need to try to consume high amounts all at once.
Iron is essential for health and transporting oxygen. A deficiency in iron causes fatigue and decreased immune function. There are two forms of dietary iron: heme and nonheme. Heme iron is found in animal foods, while nonheme iron is in plant foods.
The amount of iron that the body obtains and uses from the food is referred to as iron absorption. The iron absorption from heme iron ranges from 15%-35% while the absorption from nonheme iron is only 2%-20%. There are ways to increase the absorption of nonheme iron and meet your recommendations:
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