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Daily Nutrition

Ask the Dietitian: Getting Enough Salt and Vitamin D

Today on "Ask the RDN:" How can runners know best whether they're getting enough key nutrients, such as salt and Vitamin D?

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I run four times a week, a total of 60 kilometers [37 miles]. How do I know I’m getting enough salt?

—Craig Sullivan, Brisbane, Australia

A low level of sodium in the blood is known as hyponatremia and occurs during a time of water intoxication—when too much water is consumed without subsequent replacement of sodium. Some signs of hyponatremia include nausea, dizziness, headaches, muscle cramping, fatigue and confusion.

A situation where this could occur would be drinking an excessive amount of water during an ultramarathon without replacing the sodium lost from profuse sweating, by either drinking a sports drink with electrolytes or fueling with salty foods.

The chances that you will experience hyponatremia when running 35 to 40 miles a week is very rare as long as your diet is not restrictive and you get plenty of electrolytes from your recovery meal. Salt is so plentiful in everyday foods that your dietary salt intake will usually exceed what you need.

It is worth noting that some of the symptoms of hyponatremia are similar to hypoglycemia, or low blood sugar. If you feel any of these symptoms, my bet is that you did not fuel properly before, during or after the run. These are signs that your nutrition plan needs to be adjusted so that you are getting enough calories and nutrients at the right time to support your training.

RELATED: What You Need To Know About Electrolytes

I have a problem with not getting enough Vitamin D, especially in the winter, but I also work indoors. Is there anything extra I can eat to help with bone health?

—Ben Taylor, Manchester, New Hampshire

The majority of people do not get their daily recommended amount of vitamin D, for a variety of reasons. Our main source of vitamin D is natural sunlight. Our bodies are able to synthesize vitamin D from ultraviolet B (UVB) light. It may be difficult to get adequate sun exposure during the winter months if you spend most of your time indoors or wear protective sunscreen—which you should, to decrease the risk of melanoma.

Another reason is that vitamin D is not as prevalent in the diet as other vitamins and minerals. The only foods that naturally contain vitamin D are seafood, egg yolks and mushrooms. Fortunately, many foods are fortified with vitamin D to meet the Institute of Medicine’s recommended daily intake. Foods commonly fortified with vitamin D include milk and milk alternatives, some juice products, breads, cereal, yogurt and cheese.

If you have a hard time getting enough vitamin D in your diet, get little sun exposure or have a history of bone injuries you may require an assessment, either through blood testing by your physician or analysis by a credentialed dietitian, to determine if vitamin D supplements should be part of your nutrition plan.

RELATED: Why Trail Runners Need To Get Enough Vitamin D

This is an installment in our online Ask the Dietitian column with Maria Dalzot, M.S., R.D., C.D.N., a La Sportiva athlete, USATF National Trail Champion, and multi-time US mountain team member. You can visit her blog at

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