There is a broad spectrum of tolerance when it comes to gluten, a protein found in wheat, barley and rye. At one end of the spectrum are people with celiac disease, a condition that triggers an immune reaction that damages the small intestine and prevents absorption of nutrients whenever gluten is consumed.

At the other end of the spectrum are people with non-celiac gluten intolerance (NCGI), or gluten sensitivity. People with gluten sensitivity, which may comprise 10 percent of the U.S. population or more, experience many of the same symptoms as celiac disease causes, including headaches, fatigue, muscle and joint pain, gas and more.

It's therefore very possible that when tennis star Novak Djokovic realized he was allergic to gluten, and subsequently eliminated it from his diet, he experienced a boost in his mental and physical health that positively impacted his skills on the tennis court. Djokovic just won Wimbledon and is now ranked as the #1 tennis player in the world!

Professional Athletes Thrive on Gluten-Free Diets

Djokovic is just the latest athlete to note that a gluten-free diet boosted his sports abilities. Last year an intriguing article in Men's Journal also described one pro cycling team's improved performance after their team doctor suggested the squad go gluten-free.

As Men's Journal reported:

""I was pleasantly surprised," says Christian Vande Velde, Garmin-Transitions's team leader, who was the first member of the team to experiment with going wheat-free during the racing season. "I just had all-around better digestion, and digestion is the biggest thing in utilizing the energy I consume."

Teammate Tom Danielson had a similar experience when he started following the diet during the Tour of Missouri in 2008. "My performance really improved a lot — there was definitely a correlation," says Danielson. "I think that my digestion is better, and because of that my sleep is better and my recovery is better.""

This is quite a departure from the typical carb-heavy pasta and bread meal that is traditionally recommended to endurance athletes. However, in my experience, there is an epidemic of people with hidden intolerance to wheat products and gluten who would benefit from avoiding it entirely, and this includes many athletes. Many simply have trouble digesting the protein, and this leads to a range of health problems.

As written in Men's Journal:

"More than 50 different types of those [gluten] fragments have been shown to cause adverse reactions, according to Dr. Michelle Pietzak, a celiac expert at the University of Southern California. "So depending on your genetic makeup, you can have an allergy, you can have celiac disease, or it could be that you're just not digesting it well," Pietzak says.

And if smooth digestion seems minor compared with strength and VO2 max, think again. "It's a huge deal," says Lim [Dr. Allen Lim, former exercise physiologist for the Garmin-Transitions pro cycling team, who advised the team to go gluten-free]. "It might be the hugest deal."

Why You, Too, May Want to Give Up Gluten

Those with celiac disease, which impacts an average of one out of every 133 people in the United States (although some studies have found that this number may be as high as 1 in 33 in at-risk populations), must avoid gluten to manage the condition, but you, too, may experience health improvements by eliminating this substance from your diet.

In fact, a primary part of our nutritional typing is that everyone start out gluten-free for 60 days.

I also recommend that everyone following my beginner nutrition plan eliminate all gluten from their diets. Among the most important foods to avoid are those gluten-containing grains that contain gliadin molecules, such as wheat.

When gliadin in gluten becomes water soluble, it is free to bind to cells in your body. If you are sensitive, your body will make antibodies to gliadin and attack the cells gliadin has attached itself to, treating those cells as an infection. This immune response damages surrounding tissue and has the potential to set off, or exacerbate, many other health problems throughout your body, which is why gluten can have such a devastating effect on your overall health.

Signs that you could be sensitive to gluten, or have celiac disease, include:

Gluten often hides in processed foods like ready-made soups, soy sauce, candies, cold cuts, and various low- and no-fat products, as well as refined grain products like bread, pizza crust, pasta, cookies and pastries.

When you cut all of these foods from your diet, you end up cutting out primarily refined carbohydrates in processed foods, which is a wise health choice for a number of reasons, including keeping your insulin levels and weight in check, while also helping you avoid food additives like fructose and preservatives.

Grains are inherently pro-inflammatory and will worsen any condition that has chronic inflammation at its root -- and not just inflammation in your gut, but anywhere in your body.

Those with celiac disease know the importance of eliminating grains from their diet, as many cannot tolerate even minute amounts of gluten, but this message has yet to take root in the collective mind when it comes to dealing with autoimmune diseases and other inflammatory conditions.

If you want to avoid heart disease, high cholesterol, type 2 diabetes or even cancer, you will want to severely limit your grain consumption, or avoid grains entirely. In my experience about 75-80 percent of all people benefit from avoiding grains, even whole sprouted grains, whether you have celiac disease, gluten sensitivity or neither of these conditions.

Going Gluten-Free is Becoming Easier

Gluten-free options are becoming much more in demand and as a result are showing up in grocery stores, restaurants and from caterers. But keep in mind, particularly if you are relying on processed gluten-free foods, that cross-contamination can and does occur, most likely during processing, and many companies simply aren't testing to make sure the final product is still gluten-free.

One study found that of the 22 naturally gluten-free products tested, seven of them would not be considered gluten-free under the proposed FDA rule for gluten-free labeling, which requires products labeled as 'gluten-free' to contain less than 20 parts per million (ppm) of gluten.

So your best bet when deciding to eliminate gluten is to primarily base your diet on lean proteins, vegetables and raw dairy products, and stick with the grains, seeds and flours available that are naturally gluten-free.

This includes:

• Rice
• Corn (only eat non-GMO)
• Quinoa
• Sorghum
• Soy (but I don't recommend eating this for other reasons)
• Flax and amaranth seed

Buckwheat and millet do not contain the gliadin molecule that can provoke the inflammatory reaction from gluten. Therefore, they are usually safe to eat as well. Be aware that it may take 30 to 60 days to notice an improvement when eating gluten-free, as it can take that long for the inflammation to completely subside. And it may be up to 9 to 12 months before the lining of your small intestine is fully healed.

You may experience benefits, such as weight loss, sooner, but as a general rule most people experience noticeable physical and emotional improvements within 6 to 9 months of eliminating gluten from their diet.