Vegan for Life - Jack Norris [13]
We’d like to say that vegans never need to worry about protein, but that isn’t entirely true. There are a few situations where vegans may fall short on meeting their protein needs.
Vegan diets that are low in protein-rich foods like legumes are likely to be too low in protein. And because low-calorie diets raise protein requirements, people who are dieting or simply not eating enough for other reasons (like chronic illness) may need to boost their intake of protein-rich foods like legumes or soyfoods.
Obviously, junk-food vegan diets—those based on potato chips, French fries, and soft drinks—can be too low in protein (and too low in just about everything else that you need to be healthy).
And extreme versions of vegan diets, such as raw foods or fruitarian regimens, are often low (or completely lacking) in the higher-protein plant foods like legumes and soyfoods and can lead to a marginal protein intake. That’s one reason these types of diets are not recommended for children.
DO VEGANS GET ADEQUATE TRYPTOPHAN?
One common belief, often voiced by critics of vegan diets, is that plant foods don’t provide adequate tryptophan. This essential amino acid is needed to make the neurotransmitter serotonin, and low levels of serotonin are linked to depression. Meat is higher in tryptophan than plants, but a well-balanced vegan diet is almost guaranteed to provide more than enough of this amino acid. The FNB recommends 5 milligrams of tryptophan for every kilogram of healthy body weight. Adding in a factor for plant protein digestion, this translates to a vegan RDA of 5.5 milligrams per kilogram of body weight or 2.5 milligrams of tryptophan per pound.
For example, a vegan who weighs 130 pounds would need 325 milligrams of tryptophan, which is easily provided on a vegan diet. A diet that includes one cup of black beans, ½ cup of tofu and one cup of brown rice would provide nearly 400 milligrams of tryptophan.
In fact, eating foods that are very high in protein, like meat, doesn’t necessarily increase the amount of tryptophan in the brain. That’s because high levels of other amino acids in these foods block absorption of tryptophan from the blood into the brain. Eating foods like legumes that provide both protein and carbohydrates can actually enhance the passage of tryptophan into the brain.6
TRYPTOPHAN CONTENT OF SELECTED VEGAN FOODS
Food Tryptophan (in millligrams)
Tofu, ½ cup 155
Oatmeal, ½ cup 118
Soymilk, 1 cup 105
Black beans, ½ cup cooked 90
Peanut butter, 2 tablespoons 78
Garbanzo beans, ½ cup cooked 70
Quinoa, ½ cup cooked 48
Brown rice, ½ cup cooked 29
Broccoli, ½ cup cooked 24
TIPS FOR MEETING VEGAN PROTEIN NEEDS
• Consume adequate calories to maintain a healthful weight. If your calorie intake is low because you are dieting or for any other reason, you may need to add a few additional protein-rich foods to your menus.
• Eat a variety of plant foods every day.
• Follow the guidelines in The Vegan Food Guide in Chapter 7 and aim for at least three to four servings of legumes in your daily menu. A serving is ½ cup cooked beans, ½ cup tofu or tempeh, ¼ cup peanuts, one cup soymilk, or 2 tablespoons peanut butter.
• If beans give you discomfort from gas production, choose more lentils and split peas (they’re less gassy) and include some veggie meats, tofu, or tempeh in your menus.
• If you include plant milks in your diet, choose soymilk at least some of the time. Milks made from almonds, hempseed, and rice are low in protein.
CHAPTER 3
VITAMIN B12:
The Gorilla in the Room
You may have heard that vitamin B12 is a controversial topic among vegans. But among nutrition professionals (including those of us who specialize in vegan diets), there is no controversy at all: All vegans need to take a vitamin B12 supplement or consume foods that are fortified with this nutrient.
Vitamin B12 is needed for cell division and formation