"When we adopt the wholefood, plant-based diet these diseases go away. The obesity melts away, the arteries open up, the insulin reception clears out and joints stop hurting."
Seeing surgeons pull yellow gunk out of patients' arteries every day in an operating theatre was the motivation Klaper needed to change his lifestyle in 1981 and become vegan.
Now he is a sprightly, slim 70-year-old. He runs 8km a day and takes no regular medication.
He puts his health down to eating plant-based whole foods for 36 years. An average day for him is porridge with fruit and almond milk for breakfast, while lunch and dinner are a mix of hearty soups, salads, always with a side of steamed green and orange vegetables.
The human body evolved from the same ancestors that gorillas and bonobos evolved from, Klaper said.
Klaper believed the medical profession didn't have a respect for nutrition as it was seen as "sissy science" and doctors were reluctant to prescribe diets that they themselves weren't keeping. Instead they prefer to prescribe drugs and perform surgeries, Klaper said.
"We've got to stop pretending food doesn't matter. It's the chief determiner, even greater than genetics.
"We are herbivores by design. When we eat the diet of lions the flesh produces many imbalances in our body. It causes inflammation and sets us up for plaque formation."
Klaper was the medical director of White Cross in Whangarei from 2006 to 2009. He currently serves on the staff of the TrueNorth Health Centre in California, a nutritionally-based medical clinic.
The Nutrition in Healthcare symposium tour will be held at the University of Auckland on November 21.
Tips for moving towards a plant-based diet
• Start by eating lots of the fruit and veges you like the most. Increase your intake.
• Learn how to use a vegetable steamer and cook dark green leafy vegetables and yellow or orange vegetables in it every day. For example, steamed spinach and silverbeet with butternut squash or brussels sprouts and carrots.
• Explore the world of healthy soups, curries and stews. It's a delicious way to pack plant-based nutrients into a single portion.
• Freeze portions of vegetarian stews, soups and curries so you can heat and eat.
• Think of junk food as holding a chunk of sugar in your hand that will age you, make your arteries stiff and lead you towards dementia - then ask yourself "is it worth it?"