More and more women are getting into health and fitness. That’s great, but so many have questions about nutrition, healthy meal plans, and what they need for their bodies. Because women need fewer calories than men, I always emphasize that what ever diet (or meal plan) is followed, it must be well formulated. While it is important for everyone to consume a healthy diet, there are considerations across different age groups, especially for active people and athletes. Today we are going to look at 4 key nutrients for active females and how they help the body. In addition to the three macronutrients: carbohydrate, protein, and fat, active females need to ensure they consume adequate amounts of iron, Vitamin D, calcium, and antioxidants. Let’s have a look at each one.
Iron is a part of our hemoglobin, a protein that allows the body to bring oxygen from the lungs into the tissues. It is also found in myoglobin, which is a protein that supplies oxygen to the muscles, especially important during physical activity. Iron aids in metabolism, growth, development, and it plays a role in the creation of hormones and connective tissue, and it is partially responsible for the normal functioning of our cells. Not only do many people not consume adequate amounts of iron in the diet, but female athletes may have even less of the mineral. Women do lose some iron during their menstrual cycle and some athletes will have greater losses in their sweat, urine, and feces. When iron levels are suboptimal, the functionality of muscles is limited and overall work capacity is thereby reduced.
Iron comes from both animal (heme) and vegetable (non-heme) sources. Meat and seafood, especially oysters, are rich sources. Nuts, beans, certain vegetables, and cereal and grain products that have been fortified are some non-heme sources. Furthermore, heme-iron is more easily absorbed and has better bioavailability than non-heme iron, but the addition of ascorbic acid (Vitamin C) enhances absorption. A good habit for vegetarians is to add a Vitamin C containing source of food at mealtime like lime juice on some bean and vegetable tacos, for example. The recommend daily allowance (RDA) for iron varies throughout the lifecycle, but females aged 14-18 need mg/day and women 19-50 need 18 mg/day (more when pregnant and lactating). To give you an idea, 3 ounces of oysters contain 8 mg, 1 cup of canned white beans contains 8 mg, and one half cup of boiled spinach contains 3 mg. Vegetarians and long distance runners (due to “foot strike hemodialysis,” a breakdown of the red blood cells in the blood vessels after repeated force to the foot), may be at a higher risk for iron deficiency and should be screened regularly. According to the Position Statement from the Academy for Nutrition and Dietetics, these athletes should aim for more than the RDA of 18 mg of iron per day.
Vitamin D is a fat soluble vitamin that promotes calcium absorption and helps maintain appropriate levels of calcium and phosphorus, both of which aid in bone mineralization. It helps with bone growth and without it, bones can become brittle and thin. It also helps with cell growth, it plays a role in neuromuscular and immune function, and it can reduce inflammation. Vitamin D can enhance athletic performance and more and more studies show it may help injuries, be effective during periods of rehabilitation, improve neuromuscular function, increase the size of type two muscle fibers, and decrease the incidence of stress fractures.
The body produces Vitamin D through a complex process that involves UV rays from the sun. Females aged 14-70 require 600 IU (international units) per day. In addition to the sun, we get vitamin D from fatty fish like salmon (447 IU/3 ounces), tuna (154 IU/3 ounces, canned), vitamin D fortified milk (120 IU/cup), 1 large egg (41 IU, found in the yolk), and fortified cereals (amounts vary).
Athletes who have had stress fractures or other bone or joint injuries, muscle pain, or weakness, and those who have a low exposure to UVB rays (like those in northern latitudes or who cover up in the sun) may want to be assessed to determine if vitamin D levels are low.
Calcium, like Vitamin D, is important for bone health. The Academy for Nutrition and Dietetics states “It is responsible for growth, maintenance, and repair of bone tissue.” It also regulates muscle contraction, conducts nerves, and assists in normal blood clotting. If calcium levels are low, bone mineral density can lessen and lead to fractures.
Often, low calcium levels in female athletes is because of an overall low calorie diet and disordered eating. Bone formation is at it’s peak in teenage years, a time when many young women are active and concerned about body image, so this age group requires more calcium than the average adult. As we age, bone formation slows until eventually “breakdown exceeds formation,” as stated by the National Institute of Health in their fact sheet on calcium. Adequate amounts in the formative years is important- it maximizes long term bone health.
Females aged 14-18 need 1,300 mg of calcium per day and women 19-50 require 1,000 mg per day. Dairy products are great sources of biologically available calcium with 8 ounces of yogurt supplying 415 mg and 8 ounces of milk at 300 mg. Canned salmon with bones (they are soft and safe to eat) provides 180 mg for 3 ounces and one cup of raw kale provides 100 mg. Almonds are also a good source and if consuming milk alternatives, be sure to read labels and purchase one that is calcium fortified.
Antioxidants protect cell membranes from damage caused by oxidation as a result of exercise (but not the only cause). Researchers have hypothesized that regular training does place constant stress on cells, increasing some of the harmful compounds in the body. Natural levels of antioxidants, however, increase and serve as protectors to the cells. Well trained athletes may naturally create more antioxidants within the body. Athletes do not necessarily need a supplement, but should consume a wide variety of foods to ensure they consume antioxidant rich foods to include fruits like berries, brightly colored vegetables, and fiber filled avocados.
Athletes do not need vitamin and mineral supplements to improve performance as much of what is required by the body can be derived through the food we eat. They may be warranted to reverse a deficiency that already exists. If you are concerned, check with your doctor for an assessment, but otherwise, be sure to consume a nutrient dense and varied diet.