You should consider going on a combination of the alkaline diet and the food combining diet if you suffer from headaches, allergies, constipation or high blood pressure. I have been on this combination for 3 years and within the first month I started noticing improvements in my health.
Correct food combining is about not mixing foods that fight each other. It does not allow you to mix proteins (meat, fish) with carbohydrates (bread, rice, potatoes). Mixing proteins and starch causes bloating and slowing down of the digestive process. Starch needs to be digested in an alkaline environment and its breakdown begins in the mouth. Protein needs to be digested in an acidic environment. The breakdown of proteins takes place in the stomach. When you mix proteins and starches, you partly neutralise the acid in the stomach because starch is already alkaline when it leaves the mouth. It takes much longer to break down the protein causing food to stagnate and rot in the stomach. This causes many health problems.
Eating plenty of raw vegetables brings the body back in balance. It is like taking natural antacids. Meat and dairy products are known as acid-generating foods[4, 5]. Blood is slightly alkaline and its alkalinity is kept within a very narrow range [3,4]. Values outside this range can be life threatening. Eating acid-generating foods results in an excess of acid in the body fluids . They leave an acid residue. Acid interferes with the body's transport and communication systems and it changes the shape and function of proteins. The job of enzymes is to speed up (catalyse) chemical reactions in the body. Since they are proteins their functionality is altered by acids. The accumulation of acid over time eventually causes joint problems, skin conditions and allergies  and many other symptoms.
In contrast, eating foods that are low in meats but rich in fruit and vegetables produces alkalis that neutralise the excess acid [4, 5]. You should, therefore, eat alkalising foods at every meal while not mixing animal products and starches. Shelley Redford Young has authored an alkalising recipe book.
Juicing your fruit and vegetables is a great way of alkalising and ingesting various nutrients.
My Daily Eating Plan
I have cut out all yeast products such as bread. Yeast, which thrives in an acidic environment, has been associated with candida, allergies and other disorders. Instead I use rice cakes or tortillas. If I do eat bread I make sure I toast it first.
When I get hungry between meals I snack on raw almonds. Make sure that you have a large salad with each meal. Drink lots of water and try not to drink water or any fluids immediately after a meal. The stomach has to be acidic to digest proteins. Water dilutes this acid and slows down digestion.
Being on this diet has had a great effect on my health. I have eliminated all headaches and migraines and I no longer have allergies. I feel great!
If you do go on the alkaline diet, do so with the approval of your doctor and do continue to take all prescribed medications.