Sweeter, Better Tasting Yogurt:  homemade lactose free yogurt is delicious!

Jacob Schor ND FABNO

January 13, 2009

Making lactose free yogurt at home is worth the modest effort required; the resulting yogurt tastes excellent and does not require extra sweeteners. 

Few questions in life are not easily answered by Google these days.  Yet Google did not answer my query, “Can I make yogurt from Lactaid?”  This article provides the answer.

First a bit of background:

 Yogurt is sour.  These days most consumers prefer to sweeten it; sugar, honey, fruit, fake sugar, maple syrup, who doesn’t add one of these to counter the sour taste?  [OK, some of our readers will write that they don’t, but in general….]  Using lactose free milk produces a sweet yogurt without adding extra sweeteners.  First a simple lesson in sugar chemistry:

Lactose, the sugar found naturally in milk is a disaccharide. Each molecule of lactose is made up of two separate sugar molecules bound together, one of glucose and one of galactose.   Regular white table sugar is also a disaccharide, in its case composed of glucose and fructose.  During digestion an enzyme called lactase breaks apart each lactose molecule into two separate molecules.  By and large the sweetness of sugar depends on the number of molecules that reach our taste buds, not on the calories of sugar consumed.  Individual sugars vary somewhat in taste intensity, galactose is relatively weak, glucose is mid range and fructose is the sweetest, but number of molecules outweighs individual sugar intensity.

Now just a short lesson in medicine:

A fair percentage of our population stops making the enzyme lactase as they age.  As a result they find that milk and many dairy products give them indigestion.  The intestines cannot absorb lactose molecules directly into the blood stream unless it is broken down to its component sugars so the lactose stays in the digestive tract.  Bacteria in the lower intestine ferment the unabsorbed lactose producing vast quantities of gas resulting in bloating and flatulence.  The increased soluble sugars in the lower gut change osmotic pressures and can have a laxative effect similar to Milk of Magnesia.  Food manufacturers capitalize on this problem and sell milk that has been pretreated with lactase enzyme marketed especially for people with lactose intolerance.  The company that pioneered this process did so under the name Lactaid.  It appears the process is no longer under patent as most milk brands now offer lactose free product.  The most frequent complaint about this milk is that it tastes too sweet.  If you ask why, then go back and reread lesson one.

The bottom line though is that fermented lactase pretreated milk yields a ‘sweet yogurt’.  For people who are severely lactose intolerant this also yields a rare treat, yogurt that they can eat without fear of repercussion.  Many people who are just mildly lactose intolerant can still eat yogurt.  The bacteria that ferment yogurt consume a portion of the lactose originally present lowering the amount of lactose in yogurt.  There is a theory that as these bacteria are digested, enzymes within them are released that further break down the remaining lactose in the yogurt.  Even so, there is still too much lactose present in yogurt for people with significant lactose intolerance to eat in any quantity.

I started wondering if it was possible to make yogurt using these lactose free milks a few months ago.  Google provided no ready answer.  Nor did emails to the Lactaid company’s website. I did not know whether the bacteria used to make yogurt were fussy and needed lactose to eat or whether they were nutritionally flexible enough to survive on the glucose or galactose  in lactose free milk.  No doubt there is a scientific paper out there detailing this but I spend far too much scouring PubMed during work to do so for cooking recipes.  I finally gave up asking and conducted the obvious experiment.  I tried making a batch of yogurt using Lactaid.

The result was fantastic.  Following a normal recipe for yogurt yielded a nicely thickened product that tasted delicious.  As I eat some while I type, this lack of sourness gets my attention.  My first thought is that the extra sweetness hides the sour flavor.  It may be that, not having lactose as a starting material, the bacteria do not produce lactic acid.  I don’t know.

In hindsight, the answer to my original question should have been obvious from the start.  One can make yogurt out of both sheep’s milk and goat milk.  Neither contain lactose.

For those of you who want to try this at home, here’s recipe a more detailed recipe:

http://www.makeyourownyogurt.com/

Note:  For an incubator we use an old Igloo ice chest and an electric heating pad set on low.

One confession though.  I’ve never appreciated skim milk yogurt so my versions have included a glug or two of heavy whipping cream added to the milk.  Think Brown Cow yogurt but richer.

If I stop writing now our long time readers will be sure to comment.  “What, no PubMed search for the latest scientific research on the health benefits of yogurt?”

The bad news first, A paper published in December 2008 suggests that high yogurt intake may increase risk of subarachinoid hemorrhage, something you don’t want to happen.

The rest as far as I can see looks good:

A study on Swedish women published in October suggests yogurt lowers the risk of bladder cancer.

A clinically relevant paper from 2007 compared the effect of extracts made from milk, yogurt and kefir on the growth of breast cancer cells.  The milk extracts stimulated the cells to grow faster.  Both the yogurt and kefir extracts inhibited growth of the breast cancer cells.  While was good, the kefir was better by far.

“After 6 days of culture, extracts of kefir-fermented milk depressed MCF-7 cell growth in a dose-dependent manner, showing 29% inhibition of proliferation at a concentration as low as 0.63%, whereas yogurt extracts began to show dose-dependent antiproliferative effects only at the 2.5% dose. Moreover, at the 2.5% dose, kefir extracts decreased the MCF-7 cell numbers by 56%, while yogurt extracts decreased MCF-7 cell proliferation by only 14%.”

The kefir extracts had four times the effect the yogurt did at a concentration one quarter of the yogurts.  This should get our attention.  Women either at high risk or with breast cancer should be eating kefir.  Kefir’s is also a fermented milk product but not yogurt. Instead of purchasing Dannon as your starter culture consider using kefir as a starter. 

Kefir is actually quite a different business than yogurt.  While yogurt is made by fermenting milk with any of a combination of acidophilus bacteria, kefir is made from a culture of yeast and bacteria living in a symbiotic relationship.   I’m going to have to confess to never having made kefir at home.  Rebecca Wood has a nice article and instructions on making kefir.  See http://www.rwood.com/Articles/Kefir.htm

In years past we have mentioned that yogurt reduces the levels of cancer causing enzymes such as beta-glucuronidase in the digestive tract.  For example eating yogurt with barbecued meat inactivates the nasty chemicals in the meat. http://denvernaturopathic.com/barbecueandCherries.htm

Or that yogurt by lowering beta-glucuronidase, prevents the recycling of estrogen in the gut that increases breast cancer risk: http://denvernaturopathic.com/calciumdglucurate.htm

Current research continues to support this.  A 2005 study looked at how feeding mice yogurt protected them against induced colon cancer.

Reviews on yogurt and heath have been published.  Scientists at Tufts University tell us, “Some studies using yogurt, …. … showed promising health benefits for certain gastrointestinal conditions, including lactose intolerance, constipation, diarrheal diseases, colon cancer, inflammatory bowel disease, Helicobacter pylori infection, and allergies. Patients with any of these conditions could possibly benefit from the consumption of yogurt.

Yogurt has positive effects on the immune function.  “…. these studies in toto provide a strong rationale for the hypothesis that increased yogurt consumption, particularly in immunocompromised populations such as the elderly, may enhance the immune response, which would in turn increase resistance to immune-related diseases.”

None of this is really news.  I’m just preaching to the choir here.   

Speaking of which, Dr. Bloom has promised to write a bit on her upcoming choir performance. Perhaps this will serve as a reminder.

For those of you who like to read references, as is often the case, the website version of this letter contains abstracts of the studies mentioned.

http://denvernaturopathic.com/news/yogurt1.htm

 

Epidemiology. 2008 Dec 1. [Epub ahead of print] 

    Dairy Foods and Risk of Stroke.

    Larsson SC, Männistö S, Virtanen MJ, Kontto J, Albanes D, Virtamo J.

    From the aDivision of Nutritional Epidemiology, National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; bDepartment of Health Promotion and Chronic Disease Prevention, National Public Health Institute, Helsinki, Finland; and cNational Cancer Institute, National Institute of Health, Bethesda, MD.

    BACKGROUND:: Consumption of milk and other dairy foods has been associated with reduced risk of stroke, although not all studies have shown this consistently. METHODS:: We examined the association between dairy food intake and risk of stroke subtypes within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Between 1985 and 1988, 26,556 Finnish male smokers aged 50-69 years who had no history of stroke completed a food frequency questionnaire. We used Cox proportional hazards models to estimate relative risks (RRs) and 95% confidence intervals (CIs), adjusted for potential confounders. RESULTS:: During a mean follow-up of 13.6 years, 2702 cerebral infarctions, 383 intracerebral hemorrhages, and 196 subarachnoid hemorrhages were ascertained. We observed positive associations between whole milk intake and risk of intracerebral hemorrhage (RR = 1.41 for the highest vs. lowest quintile of intake; 95% CI = 1.02-1.96) and between yogurt intake and subarachnoid hemorrhage (RR = 1.83 for the highest vs. lowest quintile of intake; 95% CI = 1.20-2.80). Men in the highest quintile of cream intake had a moderate decreased risk of cerebral infarction (0.81; 0.72-0.92) and intracerebral hemorrhage (0.72; 0.52-1.00). There were no strong associations between intakes of total dairy, low-fat milk, sour milk, cheese, ice cream, or butter and risk of any stroke subtype. CONCLUSIONS: These findings suggest that intake of certain dairy foods may be associated with risk of stroke.

Am J Clin Nutr. 2008 Oct;88(4):1083-7. 

    Cultured milk, yogurt, and dairy intake in relation to bladder cancer risk in a prospective study of Swedish women and men.

    Larsson SC, Andersson SO, Johansson JE, Wolk A.

    Division of Nutritional Epidemiology, National Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden. susanna.larsson@ki.se

    BACKGROUND: Findings from epidemiologic studies of the effect of dairy foods (mainly milk) on the risk of bladder cancer have been inconsistent. OBJECTIVE: We aimed to examine the association between the intake of cultured milk and other dairy foods and the incidence of bladder cancer in a prospective, population-based cohort. DESIGN: We prospectively followed 82,002 Swedish women and men who were cancer-free and who completed a 96-item food-frequency questionnaire in 1997. Incident cases of bladder cancer were identified in the Swedish cancer registries. RESULTS: During a mean follow-up of 9.4 y, 485 participants (76 women and 409 men) were diagnosed with bladder cancer. Total dairy intake was not significantly associated with risk of bladder cancer [> or =7.0 servings/d compared with < 3.5 servings/d: multivariate rate ratio (RR) = 0.87; 95% CI: 0.66, 1.15; P for trend = 0.33]. However, a statistically significant inverse association was observed for the intake of cultured milk (sour milk and yogurt). The multivariate RRs for the highest category of cultured milk intake (> or =2 servings/d) compared with the lowest category (0 serving/d) were 0.62 (95% CI: 0.46, 0.85; P for trend = 0.006) in women and men combined, 0.55 (95% CI: 0.25, 1.22; P for trend = 0.06) in women, and 0.64 (95% CI: 0.46, 0.89; P for trend = 0.03) in men. The intake of milk or cheese was not associated with bladder cancer risk. CONCLUSION: These findings suggest that a high intake of cultured milk may lower the risk of developing bladder cancer.

J Med Food. 2007 Sep;10(3):416-22. 

    Kefir extracts suppress in vitro proliferation of estrogen-dependent human breast cancer cells but not normal mammary epithelial cells.

    Chen C, Chan HM, Kubow S.

    School of Dietetics and Human Nutrition, Macdonald Campus of McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.

    Anti-tumorigenic effects have been demonstrated in animal studies from the intake of kefir, a traditional fermented milk product believed to originate from the Caucasian mountains of Russia. In the present study, the antiproliferative effects of extracts of kefir, yogurt, and pasteurized cow's milk on human mammary cancer cells (MCF-7) and normal human mammary epithelial cells (HMECs) was investigated at doses of 0.31%, 0.63%, 1.25%, 2.5%, 5%, and 10% (vol/vol). After 6 days of culture, extracts of kefir-fermented milk depressed MCF-7 cell growth in a dose-dependent manner, showing 29% inhibition of proliferation at a concentration as low as 0.63%, whereas yogurt extracts began to show dose-dependent antiproliferative effects only at the 2.5% dose. Moreover, at the 2.5% dose, kefir extracts decreased the MCF-7 cell numbers by 56%, while yogurt extracts decreased MCF-7 cell proliferation by only 14%. No antiproliferative effects of kefir extracts were observed in the HMECs, while the yogurt extracts exerted antiproliferative effects on HMECs at the 5% and 10% doses. Unfermented milk extracts stimulated proliferation of MCF-7 cells and HMECs at concentrations above 0.31%. Peptide content and capillary electrophoresis analyses showed that kefir-mediated milk fermentation led to an increase in peptide concentrations and a change in peptide profiles relative to milk or yogurt. The present findings suggest that kefir extracts contain constituents that specifically inhibit the growth of human breast cancer cells, which might eventually be useful in the prevention or treatment of breast cancer.

Rev Iberoam Micol. 2006 Jun;23(2):67-74. 

    Kefir: a symbiotic yeasts-bacteria community with alleged healthy capabilities.

    Lopitz-Otsoa F, Rementeria A, Elguezabal N, Garaizar J.

    Departamento de Immunología, Microbiología y Parasitología, Facultad de Farmacia, Universidad del País Vasco-Euskal Herriko Unibertsitatea, Unibertsitateen ibilbidea 7, 01006 Vitoria-Gasteiz, Spain. f.lopitz-otsoa@ehu.es

    Kefir is a fermented milk beverage. The milk fermentation is achieved by the of kefir grains, a cluster of microorganisms held together by a polysaccharide matrix named kefiran. Kefir grains are an example of symbiosis between yeast and bacteria. They have been used over years to produce kefir, a fermented beverage that is consumed all over the world, although its origin is Caucasian. A vast variety of different species of organisms forming the kefir grains, comprising yeast and bacteria, have been isolated and identified. Kefir is a probiotic food. Probiotics have shown to be beneficial to health, being presently of great interest to the food industry. Kefir has been accredited with antibacterial, antifungal and antitumoural activities among other beneficial attributes. This review includes a critical revision of the microbiological composition of kefir along with its beneficial properties to human health.

Biocell. 2005 Apr;29(1):15-24.Links

    Reduction of beta-glucuronidase and nitroreductase activity by yoghurt in a murine colon cancer model.

    de Moreno de LeBlanc A, Perdigón G.

    Centro de Referencias para Lactobacilos (CERELA). Chacabuco 145, (4000) Tucumin. Argentina.

    Yoghurt feeding inhibits induced colon cancer in mice. Several studies showed the immunomodulatory effect of yoghurt which can explain this inhibition. It is possible that yoghurt bacteria can also affect gut flora enzymes related to colon carcinogenesis as reported for other probiotics in different animal tumours. The aim of this work was to evaluate the role of yoghurt starter bacteria and their cell-free fermentation products on the reduction of procarcinogen enzyme activities (beta-glucuronidase and nitroreductase). Mice injected with 1,2-dimethylhydrazine (DMH) and fed with yoghurt were used for this study. Mice given milk or yoghurt supernatant (cell free extract) were used to evaluate if the yoghurt antitumour effect is due to the starter bacteria or other components released during fermentation, that could inhibit these enzymes. We determined that yoghurt by itself maintained enzymes activities similar or lower than non-treatment control group, and the enzyme activity was also lower than milk or yoghurt supernatant groups. DMH increased the activity of the enzymes. Mice injected with DMH and fed cyclically with yoghurt presented lower enzymes activities than the tumour control group. Feeding yoghurt decreased procarcinogenic enzyme levels in the large intestine contents of mice bearing colon tumour. The results of this study provide another mechanism by which yoghurt starter bacteria interact with the large intestine of the mice and prevent colon cancer.

Am J Clin Nutr. 2004 Aug;80(2):245-56. 

    Yogurt and gut function.

    Adolfsson O, Meydani SN, Russell RM.

    Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington Street, Boston, MA 02111, USA.

    In recent years, numerous studies have been published on the health effects of yogurt and the bacterial cultures used in the production of yogurt. In the United States, these lactic acid-producing bacteria (LAB) include Lactobacillus and Streptococcus species. The benefits of yogurt and LAB on gastrointestinal health have been investigated in animal models and, occasionally, in human subjects. Some studies using yogurt, individual LAB species, or both showed promising health benefits for certain gastrointestinal conditions, including lactose intolerance, constipation, diarrheal diseases, colon cancer, inflammatory bowel disease, Helicobacter pylori infection, and allergies. Patients with any of these conditions could possibly benefit from the consumption of yogurt. The benefits of yogurt consumption to gastrointestinal function are most likely due to effects mediated through the gut microflora, bowel transit, and enhancement of gastrointestinal innate and adaptive immune responses. Although substantial evidence currently exists to support a beneficial effect of yogurt consumption on gastrointestinal health, there is inconsistency in reported results, which may be due to differences in the strains of LAB used, in routes of administration, or in investigational procedures or to the lack of objective definition of "gut health." Further well-designed, controlled human studies of adequate duration are needed to confirm or extend these findings.

Am J Clin Nutr. 2000 Apr;71(4):861-72. 

    Comment in:

        Am J Clin Nutr. 2001 Jan;73(1):133-4.

    Immunologic effects of yogurt.

    Meydani SN, Ha WK.

    Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging and the Department of Pathology, Sackler Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA. s_meydani_im@hnrc.tufts.edu

    Many investigators have studied the therapeutic and preventive effects of yogurt and lactic acid bacteria, which are commonly used in yogurt production, on diseases such as cancer, infection, gastrointestinal disorders, and asthma. Because the immune system is an important contributor to all of these diseases, an immunostimulatory effect of yogurt has been proposed and investigated by using mainly animal models and, occasionally, human subjects. Although the results of these studies, in general, support the notion that yogurt has immunostimulatory effects, problems with study design, lack of appropriate controls, inappropriate route of administration, sole use of in vitro indicators of the immune response, and short duration of most of the studies limit the interpretation of the results and the conclusions drawn from them. Nevertheless, these studies in toto provide a strong rationale for the hypothesis that increased yogurt consumption, particularly in immunocompromised populations such as the elderly, may enhance the immune response, which would in turn increase resistance to immune-related diseases. This hypothesis, however, needs to be substantiated by well-designed randomized, double-blind, placebo-controlled human studies of an adequate duration in which several in vivo and in vitro indexes of peripheral and gut-associated immune response are tested.


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