2014 – a year of fads
What an interesting year we’ve had diet-wise. Fads a plenty – paleo, sugar free, gluten free and in a year of comic book heroes on the big and small screen we have our own superhero Activated Nuts and its villian the “Anti-nutrient” Phytate.
Let’s dispell the myths, uncover the truth and shine some light on these fads.
Program Manager and Dietitian
Nuts for Life
Those following the Paleo diet believe we should only eat foods available during the Paleolithic era, 2.6 million to about 10,000 years ago, before the neolithic period when domestication of animals and agriculture began. Available foods during the paleolithic were eggs, insects, birds, reptiles, mammals, fruits, berries, honey, tubers, roots, and nuts.
Since many Paleolithic foods are no longer available or are modified by breeding, proponents of the modern Paleo diet avoid grains, legumes and dairy in the belief that modern breeding techniques have made grains less digestible and that our genes have not evolved to digest these foods, leading to chronic diseases.
The modern Paleo diet includes meat, fish, seafood, eggs, vegetables, nuts and seeds, with or without fruit. Advocates also suggest avoiding refined sugars, oils, potatoes, salt and processed foods. The modern Paleo diet appears to be a low-carb, low-sugar, high-protein diet by another name.
While the idea of eating more plant based foods and less highly processed foods is a good one, there is not a lot of convincing research on the health benefits of paleo eating.
There are eight clinical trials (1-9) comparing a paleo diet with other diets and while these preliminary results are intriguing (improvements in weight, blood glucose, blood cholesterol, insulin sensitivity and blood pressure) some of these studies have flaws which may impact the results:
- small participant numbers so under represented,
- most had short time frames (2 weeks to 3months) and although one study lasted 2 years it had a 30% drop out rate,
- lack of control groups,
- lack of consistency re what foods are included in a paleo diet – some allowed fruit even alcohol,
- diets not kilojoule controlled so any weight loss could have improved the biomarkers listed above and not the actual paleo diet or foods chosen.
Further longer term, larger studies are needed to reproduce these preliminary results.
In the mean time Mediterranean, vegetarian and low GI diets — which include nuts, wholegrains, legumes and dairy — have been more extensively researched and show positive effects on risk reduction and treatment of chronic diseases including heart disease, diabetes, obesity, and cancer.(10-20) The weight of evidence suggests wholegrains, legumes and dairy should be included in the diet.
But for those who are still going to eat the paleo way consider this – one in 12 Australians will get bowel cancer before the age of 85 years (21) and removing wholegrains and legumes from the diet also removes those nutrients which can help reduce the risk of bowel cancer. If you have a family history of bowel cancer you may like to reconsider the paleo diet.
Are you for or against following a paleo diet?
Phytate – the misunderstood good guy
One of the reasons paleo inspired people think they need to avoid wholegrains and legumes, and “activate” or soak nuts is because of the villianous “anti-nutrient” phytate. Such extreme ideas always make me wonder what the other side of the story is. Is phyate really that bad? Why is it in the very foods we need to survive? Does it have any health benefits?
Here’s what I found….
Phytates are the salts of phytic acid (also known as inositol hexaphosphate). This is a storage compound which contains calcium, magnesium and phosphate and is found in plant seeds. During germination, phytates are broken down by phytase enzymes and the minerals released are used by the plant for the developing shoot and root. Because phytate binds to minerals it makes them less available for absorption by the body. For some people who rely solely on only a few types of food this could lead to mineral deficiencies. Culturally however there are ways to process foods to naturally reduce phytates such as soaking, malting, leavening and fermenting. These processes either increase the level of phytase to break down phytate or they contain other compounds that help do that such as lactic acid. Of course for most people eating a varied diet mineral deficiencies are rare, even for vegetarians relying on plant foods rich in phytates such as wholegrains, legumes and nuts.
On the flip side phytates actually have many health benefits and preliminary research is undercovering more such as having antioxidant and anticancerous effects, improving carbohydrate metabolism, reducing calcium kidney stones, reducing bone mineral loss and possibly even reducing oxidative stress in the brain.(23-39)
To demonise phytates based on their negative impact on mineral bioavailability alone means ignoring the evidence for their health benefits. Australians following well-balanced diets do not need to ‘activate’ their grains and seeds to reduce phytates. But if you like the flavour and softer texture of soaked nuts that’s OK too. Just remember to eat a handful of nuts a day, legumes a few times a week and choose mostly wholegrains.
Does it surprise you that phytates are not the villain but the good guy?
I won’t quit sugar – here’s why
I find it distressing that proponents of eating sugar-free are selling sugar-free cook books which in fact still use sugars in their recipes. Those sugars may not be traditional white, brown or raw crystallised sugars but instead they suggest using the more expensive rice malt syrup, barley malt syrup, dextrose (just another word for glucose) and other types of sugars. It’s misleading and deceptive to suggest that sugars are different when they all provide a similar energy content, and that somehow their “sugar-free” cake recipes are any healthier than any other sugar laden cake recipes.
Did you know that nuts naturally contain sugars?
Yes depending on the nut variety nuts contain about 2-6g sugars per 100g and that the type of sugar they contain is sucrose. Sucrose is the type of sugar found in abundance in sugar cane which is juiced and crystallised to white, raw or brown sugar.
Does this mean we should avoid eating nuts because they contain sugars?
Not at all – nuts are seeds and the sugars are naturally present in nuts to help the seed when it germinates. Sugars provide energy to grow a root and shoot. These sugars also help give flavour characteristics to the “nuttiness” of nuts.
Nuts can also affect our blood glucose levels. Adding nuts to meals with carbohydrate can also reduce the rise in blood glucose levels after eating so nuts have a Glycemic Index (GI) lowering affect. Only two nuts have been GI tested because they contain enough carbohydrate to be tested: cashews and chestnuts and both are low GI. Low GI meals and diets provide sustained energy, helping to control appetite.
Raw natural nuts are a great every day nut choice so remember to eat a handful a day. Nuts that contain added sugars such as: chocolate coated, caramelised, vienna and honeyed nuts are a great choice for parties and festive occasions such as Christmas.
Are you concerned that sugar-free cookbooks still suggest using sugars?
This blog has been adapted from my articles on these topics in Medical Observer – the GP magazine – visit https://www.medicalobserver.com.au/clinical-review/nutrition
- O’Dea K. Marked improvement in carbohydrate and lipid metabolism in diabetic Australian aborigines after temporary reversion to traditional lifestyle. Diabetes. 1984 Jun;33(6):596-603.
- Osterdahl M et al Effects of a short-term intervention with a Paleolithic diet in healthy volunteers. Eur J Clin Nutr. 2008 May;62(5):682-5.
- Frassetto LA et al Metabolic and physiologic improvements from consuming a Paleolithic, hunter-gatherer type diet. Eur J Clin Nutr. 2009 Aug;63(8):947-55.
- Lindeberg S et al A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease. Diabetologia. 2007 Sep;50(9):1795-807.
- Jönsson T et al A Paleolithic diet is more satiating per calorie than a Mediterranean-like diet in individuals with ischemic heart disease. Nutr Metab (Lond).2010 Nov 30;7:85.
- Jönsson T et al Subjective satiety and other experiences of a Paleolithic diet compared to a diabetes diet in patients with type 2 diabetes. Nutr J. 2013 Jul 29;12:105.
- Jönsson T et al Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study. Cardiovasc Diabetol. 2009 Jul 16;8:35.
- Ryberg M et al A Palaeolithic-type diet causes strong tissue-specific effects on ectopic fat deposition in obese postmenopausal women. J Intern Med. 2013 Jul;274(1):67-76.
- Mellberg C et al Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. Eur J Clin Nutr. 2014 Mar;68(3):350-7.
- Messina V. Nutritional and health benefits of dried beans. Am J Clin Nutr. 2014 May 28;100(Supplement 1):437S-442S.
- Koloverou E et al The effect of Mediterranean diet on the development of type 2 diabetes mellitus: A meta-analysis of 10 prospective studies and 136,846 participants. Metabolism.2014 Jul;63(7):903-911.
- Schwingshackl L et al Adherence to Mediterranean diet and risk of cancer: A systematic review and meta-analysis of observational studies. Int J Cancer. 2014 Oct 15;135(8):1884-97.
- Kastorini CM et al The effect of Mediterranean diet on metabolic syndrome and its components: a meta-analysis of 50 studies and 534,906 individuals. J Am Coll Cardiol. 2011 Mar 15;57(11):1299-313.
- Huang T et al Cardiovascular disease mortality and cancer incidence in vegetarians: a meta-analysis and systematic review. Ann Nutr Metab. 2012;60(4):233-40.
- Key TJ et al Mortality in vegetarians and non-vegetarians: a collaborative analysis of 8300 deaths among 76,000 men and women in five prospective studies. Public Health Nutr. 1998 Mar;1(1):33-41.
- Bhupathiraju SN et al Glycemic index, glycemic load, and risk of type 2 diabetes: results from 3 large US cohorts and an updated meta-analysis. Am J Clin Nutr.2014 Apr 30;100(1):218-232.
- Greenwood DC et al Glycemic index, glycemic load, carbohydrates, and type 2 diabetes: systematic review and dose-response meta-analysis of prospective studies. Diabetes Care. 2013 Dec;36(12):4166-71.
- Fleming P et al Low-glycaemic index diets in the management of blood lipids: a systematic review and meta-analysis. Fam Pract. 2013 Oct;30(5):485-91.
- Goff LM et al Low glycaemic index diets and blood lipids: a systematic review and meta-analysis of randomised controlled trials. Nutr Metab Cardiovasc Dis. 2013 Jan;23(1):1-10.
- Schwingshackl L et al Long-term effects of low glycemic index/load vs. high glycemic index/load diets on parameters of obesity and obesity-associated risks: a systematic review and meta-analysis. Nutr Metab Cardiovasc Dis. 2013 Aug;23(8):699-706.
- National Health and Medical Research Council (2013) Australian Dietary Guidelines. Canberra: National Health and Medical Research Council.
- Shamsuddin, A. M., Inositol phosphates have novel anticancer function. J. Nutr. 1995, 125, 725S–732S.
- Fox CH, Eberl M. Phytic acid (IP6), novel broad spectrum anti-neoplastic agent: a systematic review. Complement Ther Med 2002; 10: 229-234.
- Bozsik A et al Molecular mechanisms for the antitumor activity of inositol hexakisphosphate (IP6). Cancer Genomics Proteomics. 2007 Jan-Feb;4(1):43-51.
- Graf E, Eaton JW Suppression of colonic cancer by dietary phytic acid. Nutr Cancer. 1993;19(1):11-9.
- Kapral M et al Induction of the expression of genes encoding TGF-beta isoforms and their receptors by inositol hexaphosphate in human colon cancer cells. Acta Pol Pharm. 2013 Mar-Apr;70(2):357-63.
- Kapral M et al The effect of inositol hexaphosphate on the expression of selected metalloproteinases and their tissue inhibitors in IL-1β-stimulated colon cancer cells. Int J Colorectal Dis. 2012 Nov;27(11):1419-28.
- Grases F et al Urinary phytate (Myo-inositol hexaphosphate) in healthy school children and risk of nephrolithiasis. J Ren Nutr. 2014 Jul;24(4):219-23.
- Prieto RM et al Effects of Mediterranean diets with low and high proportions of phytate-rich foods on the urinary phytate excretion. Eur J Nutr. 2010 Sep;49(6):321-6.
- Saw NK et al Effects of inositol hexaphosphate (phytate) on calcium binding, calcium oxalate crystallization and in vitro stone growth. J Urol. 2007 Jun;177(6):2366-70.
- Grases F et al Phytate (Myo-inositol hexakisphosphate) inhibits cardiovascular calcifications in rats. Front Biosci. 2006 Jan 1;11:136-42.
- Hanson LN et al Effects of soy isoflavones and phytate on homocysteine, C-reactive protein, and iron status in postmenopausal women. Am J Clin Nutr. 2006 Oct;84(4):774-80.
- Kim JN et al Phytic acid and myo-inositol support adipocyte differentiation and improve insulin sensitivity in 3T3-L1 cells. Nutr Res. 2014 Aug;34(8):723-31.
- López-González AA et al Protective effect of myo-inositol hexaphosphate (phytate) on bone mass loss in postmenopausal women. Eur J Nutr. 2013 Mar;52(2):717-26
- López-González AA et al [The influence of consumption of phytate on the bone mass in postmenopausal women of Mallorca]. Reumatol Clin. 2011 Jul-Aug;7(4):220-3.
- Lopez-Gonzalez AA et al Phytate levels and bone parameters: a retrospective pilot clinical trial. Front Biosci (Elite Ed). 2010 Jun 1;2:1093-8.
- López-González AA et al Phytate (myo-inositol hexaphosphate) and risk factors for osteoporosis. J Med Food. 2008 Dec;11(4):747-52.
- Anekonda TS et al Phytic acid as a potential treatment for alzheimer’s pathology: evidence from animal and in vitro models. J Alzheimers Dis. 2011;23(1):21-35.