It is well known that calcium is essential for bone health, and that inadequate intakes of calcium can lead to osteoporosis.  However, many people don’t realize that Vitamin D is needed for the absorption of calcium.  In fact, without vitamin D, calcium passes through the intestines unabsorbed, leaving the bone undersupplied even when calcium intakes are adequate.¹  Vitamin D also helps to transport calcium into the bone, which enhances bone mineralization, and it stimulates the retention of calcium by the kidneys making more calcium available for the bones.  In addition to aiding with bone mineral density, vitamin D has been found to improve balance in the elderly, which can help reduce the risk of falls.  Although studies have not all been consistent in showing this, it could prove to be another example of how vitamin D can reduce the risk of fractures.^2,3

There are two forms of Vitamin D that are important to humans, vitamin D₂ (ergocalciferol) and vitamin D₃ (cholecalciferol).  Vitamin D₂ is derived from plant sources but its contribution in the diet is minor.  Vitamin D₃ is derived from animals and is found naturally in egg yolks, liver, fatty fish and butter.  Since these are primarily the only foods that naturally contain vitamin D, some foods are fortified with the nutrient such as milk.  Humans can also synthesize vitamin D₃ from the diet or when skin is exposed to ultraviolet-B rays from sunlight. 

So how much Vitamin D is needed?  Depending on age, the amount of Vitamin D needed by the body varies. (Vitamin D is most commonly expressed in international units (IU) but is sometimes seen in micrograms (mcg)).  The recommendations are as follows:

• 1-50 years: 200 IU (5mcg) or approximately 2 cups of Vitamin D fortified Milk.
• 51-70 years: 400 IU (10mcg) approximately 4 cups of Vitamin D fortified Milk.
• 71 years and older: 600 IU (15mcg) approximately 6 cups of Vitamin D fortified Milk.

However, there has been debate as to whether the current recommendations should be increased due to growing evidence indicating that they may not be adequate to meet nutrition needs or support bone health.  This topic has recently received a lot of attention due to a significant rise in the number of people who have been diagnosed with vitamin D deficiencies.  When the Dietary Reference Intakes (DRIs) were set, it was presumed that the average adult gets the majority of their vitamin D from sunlight exposure with the diet contributing a small amount of this nutrient.  Vitamin D deficiencies have been found to occur in people with limited sun exposure; particularly those who live in northern latitudes, smoggy cities or those who are housebound. 

In order to get adequate vitamin D from the sun, it only takes about 10-15 minutes of exposure to the hands, face and arms a few times a week for most people.  However, those with a darker pigment may require longer exposure to the sun, and the use of sunscreen with an SPF of 8 or greater prevents vitamin D synthesis. 

For those who are shielded from the sunlight, a vitamin D supplement should be considered because it is very difficult to get adequate amounts of vitamin D in the diet alone.  The average person is estimated to only consume about 150 IU from food sources.  When choosing a supplement, Vitamin D₃ is the preferable source because it is more stable and 3.4 times more potent than vitamin D₂.  As demonstrated in several studies, approximately 800 IU/day has been the dosage shown to help maintain bone density and reduce the risk of fractures in the elderly.^4,5  Supplementing the diet with both calcium and vitamin D has been found to be more effective at preventing fractures than calcium or vitamin D supplements alone.⁶  It is important to note that people with hyperparathyroidism, sarcoidosis and those on calcium-channel blockers or thiazide diuretics should talk with their doctor before starting a vitamin D supplement.

Upper limits (ULs) have been set at 2,000 IU/day (50mcg) for adults, but some feel that the safe ULs may be as high as 4,000-10,000 IU/day.  Too much vitamin D can cause herpercalcemia, bone loss, kidney stones and calcification of soft tissues and the kidneys, but this is rarely seen in less than 40,000IU/day,⁷ and sunlight can not cause toxicities.  However, until more research is available to determine the safety of higher doses, it would be prudent to limit intakes to intakes to a maximum 2,000 IU/day. 

References:

1. Whitney EN, Rolfes SR. Understanding nutrition: seventh edition. St. Paul, MN: West Publishing Company; 1996

2. Flicker L, MacInnis RJ, Stein MS, et al.  Should older people in residential care receive vitamin D to prevent falls? Results of randomized trial. J Am Geriatr Soc.  2006;54:1020-1021.

3. Bischoff-Ferrari HA, Dawson-Hughes BD, Willett WC, et al.  Effect of vitamin D on Falls: a meta-analysis.  JAMA. 2004; 291:1999-2006.

4. Chapuy MC, Arlot ME, Duboeuf F, et al. Vitamin D3 and calcium to prevent hip fractures in the elderly women. N Engl J Med. 1992;327:1637-1642.

5. Vischoff-Ferrari HA, Willett WC, Wong JB, et al. Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials. JAMA. 2005;293:2257-2264.

6. Meyer HE, Smedshaung GB, Kvaavik E, et al. Can vitamin D supplementation reduce the risk of fracture in the elderly? A randomized controlled trial. J Bone Miner Res. 2002;17:709-715.

7. Parfitt AM, Gallagher JC, Heaney RP, et al. Vitamin D and bone health in the elderly. Am J Clin Nutr. 1982;36:1014-1031.

If so, here are some Tips for getting back on track.  Many people think of their diet in terms of black or white.  They eliminate all the “junk” food and follow a very rigid diet, or they completely go off the wagon and eat everything and anything they want.  When you think about a healthy eating plan don’t think of it as black or white, but recognize that there are shades of gray.  Allowing for flexibility and getting rid of the “all-or-nothing diet mentality” is very important for staying on track with your meal plan (especially around the holiday season). The following are some things to remember when your eating hasn’t gone as planned:

• One day doesn’t make or break a healthy eating plan.  It is the choices that are made day after day that really make a difference.  Remember, there are 3,500 calories in a pound of fat, so it is unlikely that a bad meal choice or a bad day would contribute to any significant weight gain.

• You can’t do anything to change the past; you can only control the choices you make in the future.  Don’t beat yourself up over poor food choices you may have made…it won’t do any good and it can only sabotage your weight loss efforts.  When you get down on yourself, you are more likely to give up all together and that’s what really causes weight gain.  So instead, examine the situation that caused you to overeat, and put a plan in place for the next time you are faced with the situation to prevent it from happening again.  The following is an example:
  • You had leftover pie in the house from Thanksgiving dinner and ended up eating quite a bit more than you had planned.  Instead of getting upset with yourself, think about what you can do to correct the situation.  Get the pie out of the house to minimize temptation (give it to a friend, take it to work or throw it out).  Plan for the future.  Next time plan to send the pie home with a family member or friend so that it is not in your house.  Another option would be to freeze the leftovers so you have it for company in the future but it is not so tempting to eat.

• Do the next best thing!  If you overate, you can often compensate for the extra calories by asking yourself the following question: “What is the next best thing I can do to get back on track?”  Go for a walk, plan the next meal carefully, clean up your environment, or go grocery shopping for healthy foods.  Often the extra calories from one meal can be counterbalanced by having the next meal be lighter and lower in calories or adding in a little extra activity.

The sooner you get back on track the better!  It is easier to lose 1-2 pounds of weight gained over Thanksgiving week than to throw in the towel and say that you’ll worry about it in the New Year when that weight gain has been multiplied.    

Many people believe that in order to lose weight they must combine a very low calorie diet with a strenuous exercise plan.  While this may work temporarily, it is unlikely that this type of behavior can be maintained for a long period of time.  The small changes that are easy to make are the ones that last, and over time they can lead to a significant weight loss.   Just think if you can cut out 100 calories a day, it can lead to a 10 pound weight loss at the end of the year.  Considering the average person gains 1-2 pounds per year, that is sizable amount.

The following is an example of how to make substitutes with lower fat and calorie foods that can really make a difference over time:

I had another question from a reader regarding what to eat before a competition.

Q: I know carbs are good before a game.  Is a powerbar good?  What else could I eat?

A: Yes, you want to eat carbs before a game.  It is ideal to eat anywhere between 1-4 hours prior to a game.  If you have 4 hours before a game, that should give you adequate time to digest a meal that has carbs, protein and a some fat.  Therefore, you have a lot more flexibility with the types of food you are eating.  However, if you only have 1 hour before a game you will want to stick primarily to carbohydrates since they are digested more rapidly. 

A power bar can be a good choice because it is high in carbohydrates, with ~30-45 gm carbohydrate depending on the bar.  However, there is nothing that makes a power bar better than other snacks that are high in carbs (although that is what their marketing department would like you to believe).  Some other good high carb snacks for before a game are:

• Bagel, English Muffin, or toast (plain or w/ low-fat cream cheese or jelly)
• Fresh fruit, dried fruit or fruit juice
• Granola Bar (i.e.: Quaker, Kashi, Pria, South Beach) Almost any bar will be a good choice, but remember it’s the carbohydrates, not the protein, that will give you the most benefit at this time.
• Hard or Soft Pretzels
• Dry Whole Grain Cereal or Granola
• Crackers
• Pasta with marinara sauce

I recently received the following question from a reader:  

Q: I don’t drink any soda or anything but water ( and some Gatorade or vitamin water when I am playing). Can I be drinking too much water?  I drink about 136 oz of water a day. (Like 8 bottles).

A:  Yes, it is possible to drink too much fluid which can lead to a condition called hyponatraemia (low levels of sodium in the blood).  This only occurs in extreme cases, and is most often seen in prolonged exercise (>2 hours) when large volumes of low-sodium drinks are consumed and very little sweat is lost.  This has mostly been seen in long distance runs, like marathons, and is more common with women.  Drinking beverages which contain sodium, like a sports drink, can lower the risk of hyponatremia.

Dehydration is much more common among athletes.  On average, a person needs a minimum of 4 cups (32 oz) of fluid for every 1,000 calories.  Any sweat losses with exercise would increase your fluid needs beyond that.  There is not a “one size fits all” fluid replacement plan because athletes vary greatly with the amount of sweat they lose with activities.  Fluid losses are affected by several factors:

• Genetics and build- some people naturally sweat more than others, and larger athletes sweat more than smaller one.
• Fitness levels- as your fitness improves, you will start to sweat sooner when you exercise and in larger volumes
• Type of exercise- more intense exercise will increase sweat losses
• Temperature- Hot, humid weather causes people to sweat more
• Medications- certain medications change fluid needs.

People often lose around 2-4 pounds (4-8 cups or 32-64 oz) per hour with moderate exercise in a mild environment.  The best way to determine fluid losses is to weigh yourself before and after you exercise and then factor in the weight of any drinks consumed.  An example: 

Pre-exercise weight = 150 pounds

Post-exercise weight= 145 pounds

Volume of fluid consumed during exercise =16 oz (1 pound)

Exercise duration = 2 hours

Calculations:

Fluid deficit = 150 lb – 145 lb = 5 lb

Total sweat loss= 5 lb + 1 lb consumed = 6 lb

Sweat rate = 6 lb/ 2 hours = 3 lb per hour

You want to drink 2 cups of water for each pound lost.  If you gain weight during exercise, then that will show you that you are drinking more than you need (that is when you can run the risk of over hydration).  If that seems like too much work, you should just monitor the color of your urine.  It should always be a light yellow and relatively odorless…if it gets darker colored than straw, you should be drinking more. 

A good guideline for hydrating yourself with exercise is as follows:

I would recommend sports drinks that replace sodium and electrolytes over vitamin water (although that is not the worst choice).  Some good choices are:

• Gatorade
• PowerAde
• PB Fluid & Electrolyte Replacement

The 17 cups of water a day that you are currently drinking, may be appropriate if you are sweating a lot with your sport (or if you are doing very physical work at your job that causes you to sweat).  However, it would likely be quite a bit more than you would need on days that you are doing little activity.  I would use the above information to assess your needs. 

What should I eat before a game?  That is one of the most popular questions I get from athletes.  When you’re planning a pre-workout meal, you will want to take the following into consideration:

• Carbohydrates are your body’s preferred energy source.
  • They are broken down rapidly.
  • Some of the extra carbohydrates are stored in the muscle as glycogen.  These reserves provide your body with the energy you need throughout the competition.
• Protein is harder for your body to digest.
  • Protein increases your fluid needs and can impair performance in the heat.
• Fat is hard to digest and can stay in your stomach for over 4 hours.

Therefore, a precompetition meal should be high in carbohydrates, low to moderate in protein and low in fat.  Some examples of good precompetition meals include the following:

• Turkey Sandwich with pretzels, fruit and low-fat yogurt
• Spaghetti with a slice of bread and skim milk
• Bagel with low-fat cream cheese and juice
• Thick crust pizza with Gatorade (avoid the high-fat toppings like pepperoni)
• Baked potato with chili and milk

It is best to experiment with new foods on practice days and go with the meals you know work on game days.  Everyone tolerates foods differently…you must know your body and know what works for you!  Keeping food journals can be a good way to track which meals work and which don’t.