Which diet is best suited to which patient?

It would not be wrong to say nutrition has become the most debated topic in health. Every week, a new dietary supplement is recommended to treat different health problems. Entering diet in Google produces 549 million results. One study may advocate consuming certain foods, while another argues the opposite. Until recently, nutrition was not sufficiently covered in medical schools, but this seems likely to change. Is healthy living based solely on nutrition? Certainly not, but diets that benefit particular diseases or reduce the risk of developing them do exist.

Hypertension and the most beneficial diet

Topping the list of the healthiest diets, the DASH diethas been shown effective in preventing hypertension and lowering blood pressure in people with it. Resembling a salt-reduced Mediterranean diet, it includes foods high in protein and fiber: whole grains, vegetables, fruit, reduced-fat dairy, poultry, red meat, fish, nuts such as hazelnuts and walnuts, and legumes such as beans. This diet effectively lowers blood pressure and has reduced serum uric acid by lowering dietary sodium (salt) and increasing magnesium, calcium and potassium intake. It supports very low saturated-fat intake and reduced sugar intake, and is also suitable for people with diabetes.

- Related topic: What is the DASH Diet? Could it be the healthiest eating plan? How is it used?

Diet for people with diabetes

In 2013, the American Diabetes Association (ADD) published a new dietary guideline for people with diabetes. It considered individual beliefs, cultural differences and metabolic variations (glucose level, fat percentage, blood pressure, height, weight and kidney function). Patients should follow diets appropriate to their preferences, circumstances and lifestyles; they can choose Mediterranean, vegetarian or low-carbohydrate diets.

Recommendations for diabetes

According to the guideline containing nutritional recommendations for people with diabetes:

• Avoid drinks containing sugar or sweeteners (fructose, corn syrup, sucrose, etc.), such as energy drinks, vitamin waters, fruit-flavored drinks, soft drinks, sweetened iced tea and lemonade.
• Choose high-fiber foods. Consume more nutritious foods instead of processed, sugary, salty (sodium-containing) and refined foods. If taking a fixed insulin dose, continue consuming carbohydrates at the appropriate times and amounts.
• Reduce sodium intake; try not to exceed the daily limit of 2300 mg (2.3 grams). People with high blood pressure may need to reduce it further.
• Consume fish products at least 2 times weekly.
• Choose liquid vegetable oils and low-fat proteins such as poultry, nuts, beans and fish instead of saturated trans fats.
• Vitamin and mineral supplements should be used only when blood levels demonstrate a deficiency and upon a physician's recommendation. There is also insufficient evidence for cinnamon, various herbal products and supplemental nutritional products.

- Related topic: Can people with diabetes eat fruit?

Diet for cardiovascular diseases

Following the Mediterranean diet has clearly been shown to reduce the risk of deaths related to cardiovascular diseases . However, merely reducing saturated fats seems insufficient; consumption of refined foods, starch and carbohydrates (potatoes, sugar, pasta) should also decrease.

The importance of plant-based eating emerges here too: vegetables, fruit, whole-wheat breads, grains, types of beans, seeds and nuts. Olive oil, rich in monounsaturated fats, has an important place in heart-protective diets. Monounsaturated fats are rich in polyphenols that reduce chronic inflammation and consequently the risk of arterial blockage called atherosclerosis. Foods rich in omega-3 alpha-linolenic acid are also recommended for cardiovascular diseases, such as walnuts, flaxseed, flaxseed oil and regular fish consumption. The respective benefits of eating fish and taking fish oil supplements remain debated. It is striking that some studies recommending fish oil supplements were financed by their manufacturers.

Diet for kidney diseases

The aim of diets for kidney patients whose kidneys do not filter adequately is to reduce blood waste levels (for example, the protein breakdown product urea) and maintain electrolyte balance. Reducing protein intake may be recommended to prevent increased blood urea. Some patients progressing toward kidney failure should limit protein-rich foods (poultry, eggs, red meat, fish or shellfish, beans, legumes and milk).

Kidney patients must consult a dietitian about renal diets. Depending on disease stage, fluid intake may need reducing to control bodily edema (swelling) and blood pressure.

The dietitian may also reduce sodium and potassium intake and balance phosphorus and calcium. Calcium-phosphorus balance is critical to preventing the parathyroid glands from drawing calcium out of bone and causing vascular calcification (hardening of blood vessels).

As can be seen, one standard diet cannot suit every disease!

Diets for inflammatory bowel diseases

The low-FODMAP diet (reduced fermentable oligosaccharides, disaccharides, monosaccharides and polyols), discovered and introduced worldwide by Australian researchers, has been tested to reduce inflammatory bowel disease (İBS) symptoms. However, adherence is quite difficult. These poorly absorbed, rapidly fermenting short-chain carbohydrates are known to increase abdominal pain, severe cramps and diarrhea commonly seen in patients with İBS.

These diets prohibit certain carbohydrates, some fructose-rich fruits, daily fresh foods for some patients, and certain sweetener products. Because many foods must be avoided, following these diets becomes difficult, and not all İBS patients respond positively.

Foods to avoid according to the FODMAP diet:

1. Oligosaccharides:
   Apples, artichokes, asparagus, barley, beets, Brussels sprouts, broccoli, chickpeas, legumes, cabbage, lentils, peaches, peas, dates, melon, okra, dill, rye, peanuts and wheat.
2. Polyols:
   Apples, apricots, avocados, cauliflower, sour cherries, mushrooms, nectarines, prunes, fuzzy fruits, snow peas, watermelon and artificial sweeteners (sorbitol, mannitol, maltitol, xylitol)
3. Free fructose:
   Apples, artichokes, asparagus, sour cherries, mango, sugar snap peas, watermelon, honey, high-fructose corn syrup
4. Lactose:
   (Only if the patient has low lactase enzyme levels, meaning lactose intolerance)
   Milk, cream cheeses, cream, ice cream and yogurt

Gluten-free diet

Gluten-free diets came to prominence through celiac disease. Celiac disease is a lifelong, chronic allergy or sensitivity to the protein gluten, particularly affecting the small intestine. It is a long-term autoimmune disorder in genetically predisposed people. It causes gastrointestinal symptoms such as prolonged diarrhea, abdominal bloating, impaired intestinal nutrient absorption and loss of appetite, along with delayed growth and development in children. It generally begins between six months and two years, but can develop at any age.

Celiac disease involves a reaction to gluten, a protein in grains such as wheat, barley and rye.

Gluten-free diets have also been claimed to protect against cancer and even to be usable in cancer treatment, but scientific studies have not substantiated these claims.

Diets for cancer patients

Many people claim to have found a cancer cure, without proving their claims, and share their supposed treatments in books or websites to attract customers, so to speak. Is there a special diet for preventing or treating cancer? First, we must say that no special dietary method treats cancer. However, you can reduce nutrition-related cancer risk by eating a largely plant-based diet, avoiding processed meat products, minimizing alcoholic drinks and choosing healthy cooking techniques. The most effective diet for cancer prevention is again the Mediterranean diet.

Ketogenic diets: an eating plan intensively researched for cancer

Ketogenic diets, based on replacing non-starchy vegetables and carbohydrates with low-to-moderate amounts of monounsaturated and polyunsaturated fats, are used for poorly responsive epilepsy in children. They are also being investigated in cancer medicine. Carbohydrate consumption is largely prohibited, aiming to convert body fats into energy (this method is called "kenosis"). The aim is to deprive cancer cells of glucose, preventing its fermentation into lactate, and increase ketone levels and energy production in normal healthy cells.

Most animal studies provide sufficient evidence for ketogenic diets' cancer-treating (anti-tumor) effect, but evidence for such effects in humans is weak and limited to individual cases. The ketogenic diet is also very difficult to follow long term.

Diets for dementia and Alzheimer's

Many studies have shown that the Mediterranean diet benefits brain function. Its ability to reduce age-related brain shrinkage was demonstrated in a study published in the scientific publication Neurolgy in 2017, a study showing this finding. Its results showed that people following Mediterranean cuisine lost half as much brain volume over three years as those not following this diet.

Developed to protect against neurological diseases, particularly Alzheimer's, the MIND diet takes its name from the initials of “Mediterranean-DASH Intervention for Neurodegenerative Delay” and combines the Mediterranean and DASH diets. It has been observed to reduce Alzheimer's risk by %35-%53 and slow cognitive decline.

The MIND diet recommends the following eating pattern: eat 3 meals daily, always including grains and different green vegetables varying each day; drink a glass of wine daily and eat hazelnuts; consume beans every 2 days; eat nuts twice weekly and fish at least once weekly. Green fibrous vegetables are rich in lutein. In adults and older people, lutein is important for preserving intelligence and mental control.