Nutrition for Female Athletes


Recently, I have learned that many of our teenage girls, especially athletes, are not getting enough calcium in their diet. A friend of mine is a National Ski Team doc and has noted that their teenage girls are experiencing back pain and injury.  He recommended the intake of calcium carbonate with Vitamin D in order to improve bone health and reduce the risk of injury.  The following is an article that outlines the need for  this is girls.

An interesting note, this article was written in 1999 during the carb craze for athletes.  Currently the thinking is 15-30% protein, 15-30% fat and 40-70% carbs for athletes.

BY KAREN SARPOLIS, M.D.

Symptoms of Poor Nutrition And Guidelines For Eating
Poor nutrition in female athletes is often underlying symptoms such as: tiredness, performance plateaus or decreases, burn-out, and repeated injuries. Female athletes may diet more aggressively than their non-sporting counterparts (see female athletic triad). Female athletes often want to loose weight to improve their performance.

The ideal diet is based on the woman's weight and consists of percentages of various food types proportional to that weight. To start, a woman should take her weight in pounds and divide it by 2.2. This gives her weight in kilograms. Then, she multiples this number by 10. This is number of grams of carbohydrates in her diet. This makes carbos about 70% of the woman's daily calories. Unlike what we have heard with the lo carb/hi protein craze, this is much better. An athlete's body needs more energy and the human body uses carbos as its main fuel. Protein grams are the woman's kilograms times 1. This means 10-15% of calories come from protein, although some have raised this to 20-25%. The rest can be fat, about 20-30% of her calories.

Women who eat at least 1200 calories per day should only need iron or calcium supplements as a back-up. She should be able to get all her nutrients in by eating a variety of foods along these lines.

Female Athletes Are Prone To Iron Deficiency
The daily requirement of iron for girls is 18 mg. Most girls don't take that much in. And excessive sweating can further exacerbate iron loss. As with all women, menstruation increases iron intake needs. Iron deficiency or inadequate iron stores can occur without anemia and this is common in young female athletes. Still, a test indicating anemia (measuring values called hemoglobin and hematocrit) have to be viewed in perspective. Training causes the fluid in the blood to increase. This "dilutes" the values read, so there appears to be an anemia when there is not. Ferritn testing should follow any low hemoglobin/hematocrit readings in female athletes. This test indicates iron stores in the body.

Iron-rich foods, dietary supplements, and vitamin C (which helps absorb iron) can improve performance. Caffeine intake blocks iron uptake.

Calcium
Calcium intake is another nutrient where female athletes have higher needs, but fall far short of the mark. Half of all runners and 40% of dancers and gymnasts don't get enough calcium. Stress fractures which can sideline a girl for the remainder of a season are the most tangible risk. Weight bearing sports, those than involve running or jumping, are at greatest risk. (more about calcium)

It's the Calories, Stupid. Fat is OK
As mentioned, few girls or women can get by with less than 1200-1500 per day. Extremely low fat diets have risks, even if the overall calories intake is good. This is generally considered to be diets that are less than 10% fat calories. Consequences of these include: low energy and performance, and deficiencies of iron, zinc, magnesium, folate (important if the woman plans a pregnancy), vitamins E, B6, B12, C, and A. Inadequate calorie intake can be the first step down the road to the Female Athletic Triad or other eating disorders.
The Athletic Triad

What is it?
The athletic triad is composed of the three issues that tend to effect female athletes: amenorrhea, eating disorders, and osteoporosis. These three issues are of growing concern, especially due to the increasing pressure on adolescent girls to maintain an "ideal" body weight. Athletes are not immune to this kind of pressure. In fact, many sports easily lend themselves to further increasing the pressure that girls feel to be thin. Appearance and endurance sports such as gymnastics, dancing, diving, figure skating, swimming, and distance running are all sports in which girls frequently are concerned about their weight and appearance. This can lead to eating disorders, ranging from poor nutritional habits to anorexia and bulimia. Eating disorders can result in serious endocrine, skeletal, and psychiatric disorders.

The Three Components
Amenorrhea is the lack of menstrual periods. A larger number of female athletes have amenorrhea than the 5% of women in the general population with amenorrhea. Why athletes sometimes stop having their periods or stop having them regularly is not understood, but it is a well-known phenomenon. The decreased estrogen levels associated with amenorrhea may be the cause of premature osteoporosis found among female athletes. Several methods have been employed to treat premature osteoporosis, including reducing training intensity and nutritional counseling. It is very important for athletes to eat properly and to carefully monitor how much they train. Sometimes, excessive training is a sign of an eating disorder. Nutrition and training intensity are interconnected and both must be regulated to help ensure good health for the athlete. (return to article)
Calcium: An Important Mineral For Women

The Importance of Calcium for Women
The primary importance of calcium for women is its function in bone development. Young women (adolescents and young adults) need to make sure they get enough calcium, as they can achieve their peak bone mass just after this age. Adequate amounts of calcium will help her bones reach optimum bone density. This can help protect her from osteoporosis later in life. Mature women need calcium to prevent break down of bone. There is also a growing body of research that suggests that calcium may prevent PMS.

How Much Does A Woman Need?
The amount of calcium that a woman should get per day ranges from 1000mg-1500mg, depending her age group, and hormonal state.

a) Ages 11-24 (adolescents and young adults): 1200-1500 mg
b) Ages 25-50: 1000 mg
c) Pregnant and nursing: 1200-1500 mg
d) Older than 50 (postmenopausal):
-- on estrogens: 1000 mg
-- not on estrogens: 1500 mg
e) Older than 65: 1500 mg

Dairy Is Not For All Women
When calcium is mentioned, the first source that comes to mind is dairy products (milk and milk products). However, if a woman is lactose intolerant, vegan vegetarian, or allergic, has religious or other self-imposed dietary restriction, or if she just doesn’t like milk, dairy foods are not the best option.

Fat Is A Problem
Dairy products are chalk-full of fat. The non-fat options are often unappealing. For example, take an average woman taking in 2,000 calories/day and requiring 1200 mg of calcium/day. If she was to get all of her daily requirements for calcium from drinking 2% milk, she would have already used up 40% of the calories from fat that she should be getting for that day. Even worse, drinking whole milk would take up 80% of her calories from fat! The latter choice comes close to eliminating meat eating, if she wants to a diet that is low-fat, but meets her calcium needs.

Where’s The Calcium
Not to worry, there are many other ways for a woman to get her recommended daily allowance of calcium, beyond milk products.

1) Non-dairy foods: broccoli (36 mg/0.5 cup cooked), sardines (420 mg/213 g), clams, oysters, kale (90 mg/0.5 cup cooked), turnip greens (99 mg/0.5 cup cooked), and mustard greens.

2) Artificially calcium-fortified: juices and cereals. Calcium-fortified orange juice contains 320 mg/cup, while calcium-fortified cereals contain 200 mg/cup.

3) Supplements: calcium carbonate, calcium citrate, calcium gluconate, calcium glubionate, calcium lactate, tricalcium phosphate

4) Other forms: Tums, Viactive, Soy milk (200-500 mg/cup). Tums are tablets that contain calcium carbonate. One regular strength tablet contains 200 mg and one extra strength tablet contains 300 mg.

5) Milk (whole, 2%, 1%, and skim) contains 315 mg/cup and fruit-flavored yogurt contains 259 mg per ¾ cup.

Cautions With Calcium Supplements
While calcium is good for a woman’s body, too much of anything can cause problems. The body has a natural mechanism for protecting against calcium overdose, but it can be over-ridden if more than 4 grams of calcium are consumed per day. To do this, a woman would need to be taking 3-4 times the usual dose in supplement tablets a day. The two most serious effects of calcium overdose are renal damage and the deposit of calcium in other areas of the body besides the bones.

Women who are already at risk for developing kidney stones should take caution about taking supplements. They can contribute to stone formation. Any woman taking supplements may get constipation and acid stomach. Keeping total intake to 1500 mg/day virtually eliminates this problem.

Calcium supplements can be involved in drug interactions with medications. A woman should always touch base with her doctor before starting calcium supplements. Her doctor can make sure there are no drug interactions or medical reasons to avoid them.

How To Take Calcium Supplements
Putting it in the mouth and swallowing is not enough! What women eat or drink around supplement ingestion can help or hinder its absorption into the body. Thirty minutes before or after the supplement is taken is the time frame for avoiding the bad and coupling with the good. Dividing the daily supplementation is two or three doses. Avoiding bedtime doses will avoid nighttime heartburn. It doesn’t matter which form of calcium is used. They are all absorbed the same in the same circumstances.

Types of foods/situations that increase absorption of calcium supplements:
a) proteins
b) lactose (milk sugar, occurs naturally in milk)
c) Vitamin D
d) Acidic foods

The main foods that can cause decreases absorption are those that contain oxalate:
a) cocoa
b) spinach
c) kale
d) unpolished rice
e) wheat bran (only in large amounts)

Alkaline foods also interfere with absorption. Less significant factors include fat, phosphate, caffeine, and magnesium. 

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