‘When you do­nate blood and you are a ke­tone burner, do you need to eat the cookie to re­place “glu­cose”?’


Q: When you do­nate blood and you are a ke­tone burner, do you need to eat the cookie to re­place ‘glu­cose’?

A: When you are a ke­tone burner it means you al­ready have low glu­cose lev­els in your blood, so your body breaks down fat to form ke­tones. Our bod­ies can use ke­tones as an en­ergy source in the ab­sence of glu­cose. When you do­nate blood you don’t need to take in any carbs, such as the cookie, to re­place glu­cose. You can just drink wa­ter to re­place the lost vol­ume and leave it to your body to reg­u­late it­self.

Q: My son, who is 13 and very sporty, suf­fers from asthma. He re­ally suf­fers when there is a lot of pollen in the air. I know I should change his diet but I don’t know where to start.

A: There are many causes for asthma. Trig­gers such as pollen, house dust, in­fec­tion or ex­er­cise can lead to the re­lease of chem­i­cals in the lungs. This will cause con­trac­tion of mus­cles in the air­ways, as well as in­flam­ma­tion, which then leads to an asthma at­tack.

With a low-carb, healthy-fat lifestyle there is much less in­flam­ma­tion in the body and many peo­ple on this diet tes­tify to an im­prove­ment in their asthma and other al­ler­gies. My ad­vice would be to change your son’s diet to a low-carb or Pa­leo diet and ex­per­i­ment with ex­clud­ing spe­cific food types to see how it im­pacts his health.

Q: I know it is im­por­tant to avoid sugar, but can I use a ‘nat­u­ral’ sugar such as honey or fruit juice to add sweet­ness to dishes?

A: When analysing the nu­tri­tional value of 100g honey we find it con­tains 82.4g car­bo­hy­drates, of which 82.12g is sugar (about 41% fruc­tose, 36% glu­cose, 1% mal­tose and 1% su­crose). 100g of grape juice con­tains 14.2g of sugar (about 7% glu­cose, 7% fruc­tose, and a min­i­mal amount of su­crose), while 100g of ap­ple juice con­tains 9.62g of sugar (about 6% fruc­tose, 3% glu­cose and 1% su­crose). To com­pare, there is 10.6g of sugar (su­crose) in 100g of Coca-Cola.

Un­for­tu­nately, the hu­man body re­acts in the same way to the ‘nat­u­ral’ sug­ars in honey and fruit as it does to the so-called ‘un­nat­u­ral’ sugar in soft drinks and pro­cessed food. Re­search sug­gests that fruc­tose may be a cause of in­sulin re­sis­tance; high blood glu­cose, of course, leads to in­sulin re­sis­tance; and su­crose, which is a 50% mix of glu­cose and fruc­tose, can lead to an un­healthy in­crease in blood sugar lev­els – and it causes tooth de­cay. Q: Am I al­lowed to eat low-GI bread?

A: Low GI is not the same as low carb. Low GI means that the sugar chains in the food take longer to be dis­man­tled into smaller par­ti­cles (monosac­cha­rides) to be ab­sorbed, and the de­layed ab­sorp­tion process means you won’t have the same high-blood­sugar spikes as when you eat high-GI food. As an ex­am­ple, a ba­nana con­tains a large num­ber of carbs but has a low GI rat­ing.

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