Matt Fitzgerald, the author of Diet Cults, wrote that according to the research he has reviewed, most of the human population can obtain all of their macronutrient needs by eating a healthy diet, that includes a full range of healthy foods, such as vegetables, fruits, nuts, seeds, etc. He includes dairy, meat and fish in his 'agnostic plan', but if one doesn't want to eat dairy, meat or fish for ethical or health reasons [most fish now contains harmful chemicals such as mercury], then most people can still obtain all of their macronutrient needs on a whole foods plant based diet.
Here is a video of one doctor [Michael Greger] who debunked the blood typing concept [and discusses an important concept about how there can be some truths to diets (or other concepts) to make them sound good or provide some credibility...interesting for us all to consider...]: http://nutritionfacts.org/video/blood-type-diet-debunked/
What about you - have you tried the 'eat right for your type' or some similar metabolic diet program? What were your results?