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Diet and Nutrition

Weakened immune system due to vegetarian diet



I am a 22 year old female (5`7" 130#) and have been practicing a vegetarian diet (although I do eat eggs) for a year and a half. Over the last several months I have been sick (varying from the flu to sore throats to colds) almost every week. A typical day for me includes: dry wheat toast and a good multivitamin for breakfast, light yogurt, a serving of pretzels and some type of fruit for lunch, and 3 egg whites, 2 types of vegetables and a seving of fruit for dinner. I also run and lift weights several times per week. Is it possible that my immune system has been weakened due to my diet and, if so, do you have any suggestions for changes I should make? P.S. I also just had a blood test which showed my counts were normal and I am negative for HIV.


Great question. Although a vegetarian diet may be healthier for you in the long run, your current dietary habits most likely have something to do with a weakened immune system. The good news is, you can improve your diet and feel much better.

Not only are you missing out on iron and zinc (2 very important minerals associated with immunity), but your current diet is too low in calories, protein, calcium, carbohydrate and probably vitamins D and E. I am surprised that you have enough energy to run and lift weights so often!

In order to improve your overall health, I suggest that you first increase your calorie intake. Although your food choices are healthy, you are basically starving yourself. Right now, you are eating less than 800 calories per day. In order to meet your calorie and nutrient needs with your activity level, I`d say you need at the minimum TWICE that amount! So, roughly 1600-1800 Calories per day.

When your body feels as though it is "starving", it will break down it`s own tissue for calories (so muscle and fat become fuel, and you become thinner and thinner). The food you eat is meant to fuel your body, and maintain it`s usual functions (temperature control, respiration, metabolism and immunity to name a few). If you eat less than your body needs, you won`t have adequate carbohydrate, fat or protein for energy and all of these functions will slow down and become inefficient. Consequently, you will feel more tired and fatigued. Also, your immune system will be weak, and you will become ill more often.

Carbohydrate is your main energy fuel. Despite all the negative press carbohydrates have been getting due to fad diets, carbohydrates are really the foundation of a healthy diet. They provide B vitamins, fiber, iron and folic acid (due to fortification). Carbohydrates provide fuel (glycogen) for your muscles. Stored carbohydrate (glycogen) also provides energy when you are fasting (between meals and while sleeping). At the bare minimum, you should eat SIX servings per day. In fact, with your activity level, eight would be more appropriate. Right now, you are eating only TWO!

Protein foods are equally important, not just for iron, B-12, B-6 and zinc, but for amino acids (the building blocks of muscle, enzymes, hemoglobin, and immunoglobulins). If you don`t eat enough protein in your diet, you will not have adequate amino acids to repair tissue, build muscle and carry on other the above functions.

Assuming you are going to continue to eat a vegetarian diet, try to include more dried beans or lentils which provide the protein your diet is lacking. Although vegetable proteins will not provide complete protein (meaning all the essential amino acids that your body can`t manufacture), when you pair them with other foods (rice, corn, whole grain bread), your meals will provide adequate amino acids. Examples include rice and beans, pasta with milk or cheese or a peanut butter sandwich on whole wheat bread. Low fat cheese, yogurt and tofu are other good sources of protein. You should have at least 2 servings of high protein foods daily. A serving includes 1 cup of dried beans, 2-3 eggs, 2-3 Tbsp peanut butter, 2 oz cheese or tofu. Continue to take a multi-vitamin daily, and make sure it has 100% of the RDAs for iron, zinc, B-6 and B-12.

In order to optimize your iron intake while continuing a vegetarian diet, eat foods high in vitamin C along with non-animal iron foods. Vitamin C increases the absorption of non-heme (non-animal) iron. Good sources of non-heme iron include dried fruit (apricots, raisins, prunes, dates), whole grain breads and cereals and dried beans. Sources of vitamin C include broccoli, peppers, strawberries, tomatoes and citrus fruits. A great source of iron is vegetarian chili. You might also start your morning with a bowl of fortified breakfast cereal topped with strawberries, or with a glass of orange juice on the side.

Another recommendation: Why not eat the entire egg? Egg yolks contain cholesterol, but they also provide vitamin D, vitamin K and vitamin A. In moderation, eggs are an excellent source of complete protein and nutrients. Moderation means 3-4 eggs (including yolks) per week.

Finally, let`s talk dairy. Great job on picking the best dairy source (yogurt). However, at your current weight and inadequate diet, you are a prime candidate for osteoporosis (thinning and weakening of bones due to calcium loss). Ideally, you should have at least 2 dairy servings per day. In order to prevent osteoporosis, it is vital that you consume enough calcium, vitamin D and also protein. If possible, try to increase your dairy servings to 2 per day. Yogurt, skim milk and low fat cheese are excellent calcium sources, as are broccoli, kale, mustard greens and sardines (with bones). Keep up the running and weight lifting as these increase bone mass and strength. BUT, if you don`t increase your calcium intake, you may suffer stress fractures along with frequent colds and flu.

I hope this advice was useful to you. For more information, check out the websites below. Good Luck!

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Response by:

Lisa Cicciarello Andrews, MEd, RD, LD Lisa Cicciarello Andrews, MEd, RD, LD
Adjunct Faculty
University of Cincinnati