· Talk about bad science here

· Where were we? Oh yes. "Dr Gillian McKeith (PhD)", who has a peaktime Channel 4 series on "clinical nutrition", got her PhD from a non-accredited correspondence school in America and has never published any properly evaluated scientific research.

· Several of you are fans of Ms McKeith, and wrote to express how upset you were that I had childishly attacked her reputation, and not her theories. Well. Let's pick a quote at random. Chlorophyll is "high in oxygen". And the darker leaves on plants are good for you, she explains, because they contain "chlorophyll - the 'blood' of the plant - which will really oxygenate your blood." Here we run into a classic Bad Science problem. It may be immediately obvious to you that this is pseudoscientific, made up nonsense (and from the TV personality the Radio Times described as "no nonsense", no less). If it's not obvious nonsense to you, then, OK, just this once: the real science. Chlorophyll is a small green molecule that uses the energy from light to convert carbon dioxide and water into sugar and oxygen. Plants then use this sugar energy to make everything else they need, like protein, and you breathe in the oxygen, and maybe you even eat the plants. You also breathe out carbon dioxide. It's all so beautiful, so gracefully simple, yet so rewardingly complex, so neatly connected, not to mention true, that I can't imagine why you'd want to invent nonsense to believe instead. But there you go. That's alternative therapists all over.

· It's very dark in your bowels. There is no light there. Nor are there gills in your bowels. Even fish do not have gills in their bowels. Consequently the chlorophyll will not create oxygen, and even if it did, even if Dr Gillian McKeith PhD stuck a searchlight up your bum to prove a point, you would not absorb any even slightly significant amount of oxygen with your bowel. And in case you think I'm being selective, and only quoting her most ridiculous moments, there's more: the tongue is "a window to the organs - the right side shows what the gallbladder is up to, and the left side the liver." Raised capillaries on your face are a sign of "digestive enzyme insufficiency - your body is screaming for food enzymes." Thankfully, Gillian can sell you some food enzymes from her website. "Skid mark stools" (she is obsessed with faeces and colonic irrigation) are "a sign of dampness inside the body - a very common condition in Britain." If your stools are foul smelling you are "sorely in need of digestive enzymes". Again. Her treatment for pimples on the forehead - not pimples anywhere else, mind you, only on the forehead - is a regular enema. Cloudy urine is "a sign that your body is damp and acidic, due to eating the wrong foods." The spleen is "your energy battery".

· Now will somebody please explain to me how this woman can be on television, every week, wearing a white coat, talking authoritatively about "treating patients", sticking irrigation equipment into people's rectums, and coming out with sentences like "each sprouting seed is packed with the nutritional energy needed to create a full grown healthy plant" which are just simply wrong (the plant gets the energy from sunlight, using chlorophyll, like we said earlier). She is a menace to the public understanding of science, and anyone who gives her a platform should be ashamed of themselves.

· Please send your bad science to bad.science@theguardian.com