DASH was first introduced at a meeting of the American Heart Association in 1996 and later published in the New England Journal of Medicine in 1997.  The DASH trial randomly assigned 456 people to different diets to test the effects of dietary patterns on lowering blood pressure. The authors surmised that eating a diet with many different foods with blood pressure-lowering nutrients would show a greater effect on blood pressure than eating single nutrients, such as found in supplements or in a limited diet. Three diets were tested: 1) a control diet, or a standard American diet, 2) a fruits and vegetables diet, similar to the control diet but providing more fruits and vegetables and less snacks and sweets, and 3) a combination diet rich in fruits, vegetables, nuts, and low-fat dairy foods with reduced amounts of saturated fat, total fat, and cholesterol. The last two diets were richer in nutrients associated with lower blood pressure, such as potassium, magnesium, calcium, fiber, and protein. All three diets provided about 3000 mg sodium, which is more than the recommended amount from the Dietary Guidelines for Americans but less than the average sodium intake for Americans. 
The "all meat all the time" low-carb approach or strict veganism can be great options for people who thrive on clear diet rules (and those two are actually the most popular diets out there) but these extremes are not for everyone. If you prefer more of a moderate approach, the Flexitarian diet is the clear winner. The "flexible vegetarian" mindset allows you a healthy balance of plant-based foods, responsibly sourced meats, and quality fats. The best part? It's not super restrictive, so you have plenty of nutritious food options. (Start here: How to Adopt a Flexitarian Diet)
Nuts. It’s very easy to eat until the nuts are gone, regardless of how full you are. A tip: According to science, salted nuts are harder to stop eating than unsalted nuts. Salted nuts tempt you to more overeating. Good to know. Another tip: Avoid bringing the entire bag to the couch, preferably choose a small bowl instead. I often eat all the nuts in front of me, whether I’m hungry or not.
Both groups experienced no notable adverse effects in their health. In the 29 subjects who successfully completed the calorie-restricted diet, researchers observed an average 16% reduction in fasting glucose, 2.7 reduction in BMI, and loss of 6.9 kg of bodyweight.  However, in the 21 subjects that successfully completed the very-low carbohydrate ketogenic diet, subjects experienced an average 19.9% reduction in fasting glucose, 3.9 decrease in BMI, and loss of 11.1 kg of bodyweight. 
Although you'll be cutting way back on carbohydrates and sugar, some fruits are still okay to eat on the keto diet (though you'll still want to be mindful about quantity in order to remain in ketosis). The fruits that make the cut contain far fewer carbs than their off-limits cousins such as apples, pears, bananas, pineapples, papayas, grapes, and fruit juices in general.
The ketogenic diet is not a benign, holistic or natural treatment for epilepsy; as with any serious medical therapy, there may be complications. These are generally less severe and less frequent than with anticonvulsant medication or surgery. Common but easily treatable short-term side effects include constipation, low-grade acidosis and hypoglycaemia if there is an initial fast. Raised levels of lipids in the blood affect up to 60% of children and cholesterol levels may increase by around 30%. This can be treated by changes to the fat content of the diet, such as from saturated fats towards polyunsaturated fats, and, if persistent, by lowering the ketogenic ratio. Supplements are necessary to counter the dietary deficiency of many micronutrients.
While it’s true that low-carb diets do raise the so-called bad LDL-cholesterol in some people, it’s important to note that LDL-C, when influenced by diet, has never been shown to have any effect on cardiovascular risk. Large clinical trials and observational studies show that one’s level of LDL-C and the lowering of LDL-C through diet is not reliably linked to cardiovascular outcomes.21, 22, 23
The Mediterranean diet has been shown to reduce the risk of heart disease. It’s also associated with a reduced incidence of cancer, Parkinson’s and Alzheimer’s diseases. This diet emphasizes eating primarily plant-based foods including fruits, vegetables, whole grains, legumes, nuts, olive and canola oil, fish and poultry. It also encourages getting plenty of exercise, enjoying red wine in moderation and focusing on meals with family and friends.
It is completely wrong to discuss “average lifespan”. The average lifespans of pre-industrial peoples is heavily reduced by infant and early childhood mortality, which has nothing to do with lack of fresh fruit. Once you remove this bias in the numbers, pre-industrials can have lifespans almost as long as ours. And usually without many of the degenerative diseases that bother our middle and old ages.
Iwould hope to meet a diabetic nurse in the uk who was open minded about keto, but that has not been my experience as a patient. As a nurse speaking to colleagues as an equal and frmy experience has been very different. I have not spoken to one nurse with personal/professional interest in this subject that has said if they were diabetic they would follow the guidance of our health service. All have said they would do keto.
On the flip side, hypos can be an issue, especially early on…and if you treat them too aggressively, they could knock you out of ketosis. I remember my first 3 weeks on keto, my CGM trend line hugged a blood sugar of around 80. It was glorious, but I had to reduce insulin substantially through trial and error and felt like I was low every five seconds.
There are three instances where there’s research to back up a ketogenic diet, including to help control type 2 diabetes, as part of epilepsy treatment, or for weight loss, says Mattinson. “In terms of diabetes, there is some promising research showing that the ketogenic diet may improve glycemic control. It may cause a reduction in A1C — a key test for diabetes that measures a person’s average blood sugar control over two to three months — something that may help you reduce medication use,” she says.