Science does not say that.
PS: I am no vegan
PPS: And many vegans look good to me.
When the honeymoon’s over
When people first start the vegan diet, they often feel good, especially if they are used to eating a diet high in processed foods and low in vegetables. This is because the diet can function as a healthful short-term cleanse. But after the honeymoon phase, the vegan diet no longer supplies or grossly undersupplies several essential nutrients. Here is a description of the most important:
Vitamin A is found only in animal products: butter, whole dairy, eggs yolks, meats and fish. Vitamin A is needed for healthy eyes, healthy pregnancy and birth, for the immune system, for the liver, and for the kidneys and lungs. Vitamin A is also a powerful antioxidant that protects our cells from aging. Vegetables that are thought to contain vitamin A, such as carrots and sweet potatoes, actually contain beta-carotene which the body can convert to vitamin A under the right conditions. However, it takes 12-24 molecules of beta-carotene to make one molecule of vitamin A, and this requires adequate dietary fats. Not everyone can make the conversion, either. Infants and young children, diabetics, celiacs, anyone with any kind of thyroid condition, and people on very low-fat diets can’t make the conversion and must obtain vitamin A from animal products.
Vitamin D is found only in animal fat: butter, whole dairy, eggs yolks, meats and fish. The body can make vitamin D (from cholesterol) when exposed to UVB sunlight without sunscreen during “peak hours” of the day in the summer. UVB sunlight is not available during the winter in Minnesota, making year-round vitamin D synthesis impossible. Vitamin D is needed for maintaining bone health, for healthy moods and for cancer prevention. Vitamin D2 is a plant form of vitamin D found in plants such as avocado and sunflower seeds, but it is not as effective and most notably, brain tissues can’t use it.
Cholesterol is an essential nutrient. Our bodies produce around 80% of the cholesterol we needs, the rest must come from our diets. This means that vegans will automatically be at least 20% short at all times because cholesterol is found only in animal products. Cholesterol is needed for maintaining cell membranes, for the digestion of fats, for repairing damaged body tissues and cells, for producing hormones (including steroid, stress and sex hormones), for serotonin production and for higher cognitive functions.
Vitamin B12 is found only in animal products. B12 is needed for the synthesis of all new DNA in cells, for the production of energy and for the formation of myelin, which surrounds the nerves in the body and brain. A vitamin B12 deficiency is very serious and can result in irreversible nervous system and brain damage if left untreated. Early indicators of B12 deficiency include fatigue, weakness and rigid thinking. It was once thought that certain sea vegetables, miso and micro algae, contained B12. While B12 is listed as a nutrient on the labels of some of these products, the “B12” they contain is an analogue; it looks like B12, but our bodies can’t use it. Sadly, the analogue will register as B12 in a blood test, so the test doesn’t provide an accurate reading. Still worse, these analogues inhibit uptake of real B12, making the deficiency more intense.
Zinc, Calcium and Iron are all minerals that can be obtained, but are undersupplied, on a vegan diet. Zinc is an antioxidant and an enzyme activator. It is needed for the production of hormones, for the immune system and for fertility. Our best sources of zinc are red meats and oysters. Iron is necessary for maintaining the body’s supply of red blood cells, for energy and healthy moods and for cognitive function. There are two kinds of iron: heme iron, which comes from animal foods; and non-heme iron, which comes from plants. Non-heme iron isn’t easily absorbed; the body can only use around 15-20% of it. Heme iron is almost 90% absorbable. Our best sources of iron are red meats and dark meat poultry. Calcium is needed for bones and teeth, muscle function (including the heart) and for a healthy nervous system. Our best sources of calcium are dairy products and stocks made from bones.
Making protein
Perhaps the most obvious concern for vegans is obtaining enough protein. Animal foods contain all eight essential amino acids. With all eight, our bodies can make any kind of protein we need. However, if we’re missing even one, our bodies can’t make any protein. All plant foods, including soy, are low in the essential amino acid methionine. This means even if vegans are technically getting “enough” protein by meeting minimal requirements, they might not be able to efficiently use it. It is important to note that meeting minimal needs is not the same as providing optimal nutrition. For example, the U.S. RDA of 60 mg. of vitamin C will prevent scurvy, but it will not keep your immune system functioning at peak levels.
Protein is our basic building block. It keeps our tissues, muscles and bones in good repair, it makes the enzymes that regulate metabolism and digestion, it makes the precursors for hormones and it makes the neurotransmitters that determine our moods. We need to get more than just survival amounts in order to thrive.
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